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Operating temperature of photovoltaic modules: A survey of pertinent correlations
Abstract
The importance of solar cell/module operating temperature for the electrical performance of silicon-based photovoltaic installations is briefly discussed. Suitable tabulations are given for most of the explicit and implicit correlations found in the literature which link this temperature with standard weather variables and material/system-dependent properties, in an effort to facilitate the modeling/design process in this very promising area of renewable energy applications. (c) 2008 Elsevier Ltd. All rights reserved.
... Moreover, triple linear correlation (Nguyen et al. [19], Araneo et al. [31], Skoplaki et al. [32], Kichou et al. [33], Scarabelot et al. [34], Zouine et al. [27], Muneeshwaran et al. [28], Dong et al. [35], Al-Dahidi [36], Ndegwa et al. [37]) to displace a single linear correlation in the implicit model. Significantly, Nguyen et al. [19] modified the SPGMBCT model with wind speed, thermal inertia (thermal diffusivity) and irradiance resulting in an outstanding result. ...
... Considerably, Araneo et al. [31] developed a full (triple) explicit SPGMBCT model to achieve high accuracy in cell temperature prediction. Substantially, Skoplaki et al. [32] developed explicit (triple) models based on weather, material optics, thermophysical properties, cell/ambient temperature, wind speed and irradiance, which are appropriate for the design and operation of the PV system. Outstandingly, Kichou et al. [33] discovered the impact of an explicit (triple) model on floating and land-based PVs using MATLAB simulations. ...
... The first empirical solar power model is defined in Eq. (20) by the following literature (Al-Bashir et al. [43]; Scarabelot et al. [34]; Skoplaki et al. [32]) as ...
The discrepancy between the operating and design capacities of solar plants in eastern Uganda is alarming; about 35 % underperformance in solar power generation is observed. The goal of the current study is to minimize this disparity by improving the design models. Considering only cell temperature in the power generation model is responsible for the observed difference in design and operational solar power generated, the present study used a thermocouple to directly measure cell temperature, an anemometer to measure wind speed, and a solar power meter to measure irradiance. These extrinsic factors were used to modify the power generation model based only on cell temperature through the direct correlation of cell temperature, wind speed, and irradiance with solar power generation. Thus, the absence of extrinsic factors (wind speed and irradiance) in the design models is responsible for the colossal drop in solar power generated. Empirically, the missing extrinsic factors were used to transform the implicit solar power model into an explicit model. The development of a solar power generation model, multiple differential models, simulation and experimentation with a pilot solar rig served as alternate model for the prediction of solar power generation. The second-order differential model validated well with empirical solar power generated in Busitema, Mayuge, Soroti, and Tororo study areas based on RMSEs (0.6437, 0.6692, 0.2008, 0.1804, respectively), thus, narrowing the gap between the designed and operational solar power generated. Mayuge and Soroti recorded the highest solar power generation of 9.028 MW compared to Busitema (8.622 MW) and Tororo (8.345 MW), suggesting that it has a conducive site for installing future solar plants. The above results support the use of empirical explicit (triple) and second-order differential models for the design and operation of power plants.
... It is well known that temperature is the second most influential factor in photovoltaic (PV) performance. Temperature effects on PV module efficiency are well-documented [1] and many models exist for calculating module temperature [2]. Module temperature models vary in complexity, from three-dimensional finite element analysis [3] to simpler and more practical empirical approaches in one dimension [4]- [7]. ...
... A high-level thermal balance (steady-state, disregarding thermal capacitance) is given by the following equation, which expresses simply that the heat gains must balance the losses: (1) where q sun is the energy flux from the sun, q elec the energy flux removed as electricity, and the remaining three terms are the heat loss fluxes by radiation, convection and conduction (all in W/m 2 ). Conduction is usually negligible since the area of contact between the frame and mounting structure is very small, and the remaining radiative and convective losses are lumped together as q cr to produce the much simpler thermal balance equation: (2) Although q cr actually depends on a large number of parameters and properties, its main tendency is to increase as the temperature of the module (T m ) rises above the temperature of the environment (T a ). Using a one-dimensional, linear approximation of this tendency produces the thermal balance equation: ...
... The gray histogram in the background represents the distribution of available solar energy by wind speed 2 in the six IEC-61853 climate profiles combined. This makes clear that the large differences at very high wind speed are not 2 The wind speed shown has been reconverted to 10 m measurement height by undoing the conversion from 10 m to 2 m reported in [15]. necessarily going to have a large impact on energy yield predictions, but on the other hand a small difference at moderate wind speed could be significant. ...
PV module operating temperature is the second most important factor influencing system yield, after irradiance. A variety of temperature models are used within yield simulation software to predict module operating temperature, which then determines operating efficiency. Four temperature models are frequently used: PVsyst, Faiman, SAPM and SAM NOCT. Although these models are similar, their parameter values are not directly interchangeable. In this work we demonstrate the equivalence or near-equivalence of these four temperature models, and from there we develop equations to convert their parameter values back and forth. This is more than a convenience for users of simulation software. We use this capability, for example, to compare and analyze the typical and default values preset for different model/software combinations. The functions to perform the parameter conversions are made available as open-source software in pvlib-python.
... In order to determine the wind speed effect on the PV module temperature, Skoplaki et al. [21] suggested a linear model based on the thermal loss coefficient, describing the wind effect. Hasan et al. [22] developed a model based on the work of Skoplaki et al. [21], which led to: ...
... In order to determine the wind speed effect on the PV module temperature, Skoplaki et al. [21] suggested a linear model based on the thermal loss coefficient, describing the wind effect. Hasan et al. [22] developed a model based on the work of Skoplaki et al. [21], which led to: ...
... Assuming steady-state conditions [22]; • Assuming a linear relationship between the PV module temperature T C and ambient temperature T a and solar irradiance G T without any load, with the introduction of the Ross coefficient K (its definition: KG T = T C − T a [21]) that is usually falling between 0.02 and 0.04 ...
This study proposes a computational model to define the wind velocity of the environment on the photovoltaic (PV) module via heat transfer concepts. The effect of the wind velocity and PV module is mostly considered a cooling effect. However, cooling and controlling the PV module temperature leads to the capability to optimize the PV module efficiency. The present study applied a nominal operating cell temperature (NOCT) condition of the PV module as a reference condition to determine the wind velocity and PV module temperature. The obtained model has been examined in contrast to the experimental heat transfer equation and outdoor PV module performance. The results display a remarkable matching of the model with experiments. The model’s novelty defines the PV module temperature in relation to the wind speed, PV module size, and various ambient temperatures that were not included in previous studies. The suggested model could be used in PV module test specification and provide analytical evaluation.
... Besides the hourly climatic data, the average hourly climatic data within the sunshine hours of a day, namely the daily hour-average-based climatic data within the sunshine-hours (HAB-SH), is also suitable for the conventional PV estimation models as stated in [5]. Furthermore, Skoplaki and Palyvos [6] provided an overview description of the PV module operating temperature which indicated that the daily HAB-SH climatic data is applicable for the conventional PVMT estimation model to aid in the daily output power estimation. This demonstrates that the daily HAB-SH climatic data has the same function as the hourly data, and hence both can be taken as hour-based climatic data. ...
... Since the daily HAB-SH climatic data is exclusively used in the PVMT estimation model, it can be considered as the main hour-based estimation model. Moreover, the estimation method for estimating the daily output power in [6] can be regarded as the conventional multiple-time-point average-hourly (MTP-AH) estimation method, since it deals with the daily HAB-SH climatic data. ...
... According to NASA [14], the daily HAB-24 ambient temperature data and daily HTB-SH solar radiation data are the day-based data, and the hourly data of ambient temperature and solar radiation are the hour-based data as shown in Table 2. On the other hand, the uncommon daily HAB-SH ambient temperature and solar radiation data for NASA are the manualprocessing data. According to the principle presented in [5] and [6], the manual-processing daily HAB-SH climatic data have the same function as the hourly climatic data and are considered as hour-based climatic data that can be applied into the hour-based estimation model, namely the PVMT estimation model as stated in [2]. The difference between the manual-processing daily HAB-SH ambient temperature and the NASA daily HAB-24 ambient temperature is that the former does not include the data records during the night-time. ...
Based on the hourly solar radiation and ambient temperature, the hourly power estimation work is carried out using the conventional photovoltaic output power (PVOP) estimation model which is used in conjunction with the conventional photovoltaic module temperature (PVMT) estimation model. These hourly data must be processed further before they can be applied to the daily power estimation work. This estimation work is carried out using conventional estimation methods, which are the multiple estimation processes that are complex, time-consuming, and error prone. Therefore, to avoid these shortcomings, one estimation process is designed and used for daily power estimation work. However, this process produces an incorrect daily output power value due to an invalid module temperature value. Thus, a new PVMT estimation model is developed to solve the problem of the invalid value based on a simple linear regression analysis. The performance of the new model has been validated, giving a Normalized Root Mean Squared Error (NRMSE) value of 0.0215 and a Coefficient of Determination (R2) value of 0.9862. The correct daily output power value is produced with a valid module temperature value, giving a NRMSE value of 0.0034 and a R2 value of 0.9999. These results demonstrate the new model's applicability and makes the one estimation process accurate, easy, user-friendly, instantaneous, and direct in daily power estimation work. ABSTRAK: Berdasarkan sinaran matahari dan suhu persekitaran per jam, kerja-kerja anggaran kuasa setiap jam dijalankan menggunakan model anggaran kuasa dari dapatan fotovolta konvensional (PVOP) yang digunakan bersempena dengan model anggaran suhu modul fotovolta konvensional (PVMT). Data per jam ini perlu diproses dengan lebih lanjut sebelum ia boleh digunakan pada kerja anggaran kuasa harian. Kerja-kerja penganggaran ini dijalankan menggunakan kaedah penganggaran konvensional, iaitu proses penganggaran berganda yang kompleks, memakan masa dan mudah ralat. Oleh itu, bagi mengelakkan kekurangan ini, satu proses anggaran direka bentuk dan diguna bagi kerja anggaran kuasa harian. Namun, proses ini menghasilkan nilai dapatan kuasa harian yang salah disebabkan oleh nilai suhu modul tidak sah. Oleh itu, model anggaran PVMT baharu telah dibina bagi menyelesaikan masalah nilai tidak sah berdasarkan analisis mudah regresi linear. Prestasi model baharu telah disahkan, memberi nilai Ralat Punca Min Kuasa Dua Ternormal (NRMSE) sebanyak 0.0215 dan nilai Pekali Penentuan (R2) sebanyak 0.9862. Nilai dapatan kuasa harian yang betul dihasilkan dengan nilai suhu modul yang sah, iaitu nilai NRMSE 0.0034 dan R2 0.9999. Dapatan ini menunjukkan bahawa kebolehgunaan model baharu menjadikan proses anggaran lebih tepat, mudah, mesra pengguna, serta-merta dan terus dalam kerja anggaran kuasa harian.
... The various correlations found in the literature express the PV cell temperature as a function of the weather variables and also include the parameters dependent on the material and system properties, such as plate absorbance, glazing-cover transmittance, etc. Furthermore, many correlations in the literature express the negative effect that the cell temperature rise has on the electrical efficiency of the PV module [17]. ...
... Empirical correlations are divided into implicit and explicit correlations. The implicit correlations require an iterative method for resolution, using the variables that depend on other correlated parameters [4], [17]. The typical implicit relation to determining the PV cell temperature starts from the Nominal Operating Cell Temperature (NOCT), the incident solar irradiance and the external air temperature [18]. ...
... The NOCT assesses the temperature dependence and represents the cell temperature in a module exposed at 45° South to an irradiance of 800 W/m 2 at an ambient temperature of 20°C and wind speed at about 1 m/s according to the IEC 61215 standard [19]. A comprehensive overview of the PV temperature simulation is described in [17]. Moreover, some models for the description of the correlations between the PV module temperatures, ambient temperature, solar irradiance and wind have been proposed. ...
... To determine the operating temperature of PV modules, several authors have used the steady-state energy balance (Evans, 1981;Armstrong and Hurley, 2010), where the effects of radiation, convection, conduction and generated electrical energy are considered, whose resulting function depends on the environmental and physical parameters of the PV module (Sun et al., 2020;Mattei et al., 2006;Skoplaki and Palyvos, 2009;Jones and Underwood, 2001). Thus, researchers have considered all heat transfer modes encompassed in a constant or linear relationship as a function of wind velocity (Palyvos, 2008;Skoplaki et al., 2008) View factor [-] ε Emissivity [-] η Module electrical efficiency [-] η Tref ...
... NOCT model, with manufacturer data T NOCT = 43 ± 2 • C, T a,NOCT = 20 • C and G NOCT = 800 W/m 2 Skoplaki and Palyvos (2009) 3 ...
... where = to heat loss from the PV upper side. The measure of the coefficient of free convection heat transfer between either side of the panel is determined as follows by (Skoplaki & Palyvos, 2009 ...
... The experimental relationships for the coefficient of forced convective heat transfer (ℎ ) and according to = ℓ are supplied by (Skoplaki & Palyvos, 2009). ...
This study explores the integration of porous fins with phase-change materials (PCM) to enhance the thermal regulation of photovoltaic-thermal (PVT) systems. Computational simulations are conducted to evaluate the impacts of different porous fin configurations on PCM melting dynamics, PV cell temperatures, and overall PVT system effectiveness. The results demonstrate that incorporating optimized porous fin arrays into the PCM region can significantly improve heat dissipation away from the PV cells, enabling more effective thermal control. Specifically, the optimized staggered porous fin design reduces the total PCM melting time and decreases peak cell temperatures by about 5°C. This is achieved by creating efficient heat transfer pathways that accelerate the onset of natural convection during the PCM melting process. Further comparisons with traditional solid metallic fins indicate that while solid fins enable 12.2% faster initial melting, they provide inferior long-term temperature regulation capabilities compared to the optimized porous fins. Additionally, inclining the PV module from 0° to 90° orientation can further decrease the total PCM melting time by 13 minutes by harnessing buoyancy-driven convection. Overall, the lightweight porous fin structures create highly efficient heat transfer pathways to passively regulate temperatures in PVT systems, leading to quantifiable improvements in thermal efficiency of 16% and electricity output of 2.9% over PVT systems without fins.
... Also, there are several correlations have been developed for the production of cell temperature based on environmental and climate parameters. The most explicit and implicit correlations for predicting PV cell/module temperature were reviewed by Skoplaki and Palyvos [10]. Another review of the PV energy production and temperature effects for diffident sites has been prepared by Dubey et al. [11]. ...
... The atmosphere and the clouds could attentunate the sun's solar radiation prior to its arrival on the earth. The earth's surface global horizontal radiation ratio, which is G, to the horizontal extraterrestrial radiation, which stands for clearness index k T as: (10) where G is averaged over the time step (W/m 2 ) and G o is the extraterrestrial horizontal radiation, which is an average over the time step (W/m 2 ). ...
The modelling of output power for the photovoltaic system is essential for system design and local resource prediction. Accurate photovoltaic power modelling the foremost vital issue is systems efficiency analysis. The temperature plays the main role in the energy degradation of the photovoltaic systems, especially in the host sites. In this paper, experimental and theoretical investigation into the photovoltaic module energy degradation due to temperature effects. This work objectives to investigate the photovoltaic power generated due to the ambient temperature effect. The presented results show that the ambient temperature has positive effects on the photovoltaic module energy production during the winter period and negative effects during the summer period. For the proposed photovoltaic system with a capacity of 2.97 kWp the expected theoretical annual energy production by about 554.01 kWh while the annual experiment production was l493.73 kWh. The novelty of the work is to estimate the energy losses due to the ambient temperature effect on the photovoltaic energy production.
... Also, there are several correlations have been developed for the production of cell temperature based on environmental and climate parameters. The most explicit and implicit correlations for predicting PV cell/module temperature were reviewed by Skoplaki and Palyvos [10]. Another review of the PV energy production and temperature effects for diffident sites has been prepared by Dubey et al. [11]. ...
... The atmosphere and the clouds could attentunate the sun's solar radiation prior to its arrival on the earth. The earth's surface global horizontal radiation ratio, which is G, to the horizontal extraterrestrial radiation, which stands for clearness index k T as: (10) where G is averaged over the time step (W/m 2 ) and G o is the extraterrestrial horizontal radiation, which is an average over the time step (W/m 2 ). ...
The modelling of output power for the photovoltaic system is essential for system design and local resource prediction. Accurate photovoltaic power modelling the foremost vital issue is systems efficiency analysis. The temperature plays the main role in the energy degradation of the photovoltaic systems, especially in the host sites. In this paper, experimental and theoreti-cal investigation into the photovoltaic module energy degradation due to temperature effects. This work objectives to investigate the photovoltaic power generated due to the ambient tem-perature effect. The presented results show that the ambient temperature has positive effects on the photovoltaic module energy production during the winter period and negative effects during the summer period. For the proposed photovoltaic system with a capacity of 2.97 kWp the expected theoretical annual energy production by about 554.01 kWh while the annual experiment production was l493.73 kWh. The novelty of the work is to estimate the energy losses due to the ambient temperature effect on the photovoltaic energy production.
... where T a,t is the ambient temperature at time t and NOCT is the normal operating cell temperature [34,35]. NOCT is the cell temperature at the condition in which the solar radiation flux is 800 W/m 2 , the average wind speed is 1 m/s, the ambient temperature is 20°C and the electrical load is zero [36] and is usually between 42°C and 46°C [37]. In this work, the effects of temperature on solar panels are neglected. ...
... The main purpose of the optimization section is to minimize the 20-year LCC of the IWPS and a genetic algorithm does this process. The decision variables are the total area of the PV panels ( A pv), the total area of the PVT panels ( A pvt), the number of batteries (N b ), the DOD of the batteries, the installed power of the RO desalination system (Pro), the capacity of the water tank (Vwtc) and the storage capacity of the heat tank (H htc ): No P ro ≥ P s,t η η inv 2 -P e,t P ex,t = P s,t η η inv -P e,t /η η inv -P ro /η η inv (36) The following constraints are applied to the decision variables: ...
In this study, a new water and power cogeneration plant, employing photovoltaic (PV) and photovoltaic–thermal (PVT) panels simultaneously, is designed and optimized for a village struggling to provide energy and potable water in Iran. The system includes a solar energy unit to generate clean electricity and heat, and a reverse osmosis unit to produce drinking water. Techno-economic optimization is performed by implementing a genetic algorithm, and a comprehensive water and energy management strategy is designed and presented in detail, expandable for future works. A new method, the logarithmic model, is used to calculate the depth of discharge (DOD) of lithium-ion batteries, which was previously a fixed and predetermined value in previous papers. Various indices, the constraints of the optimization process, are also introduced to measure the reliabilities of different units. The effects of the system components on total cost are investigated and a comprehensive sensitivity analysis is performed to find the best solution to increase the penetration of renewable-energy systems. The results reveal that considering the depth of discharge of batteries and water storage tank capacity as decision variables reduces the system’s life-cycle cost (by 5.1% for changeable DODs). Furthermore, the simultaneous use of PV and PVT panels decreases the life-cycle cost considerably by ≤19% compared with the use of only PVT panels. Additionally, the cost of the battery causes a decrease in the cost of electricity storage and the cost of producing and storing fresh water.
... Results show that carbon utilization in PVCs still needs more investigation to enhance efficiency [50]. Skoplaki and Palyvos surveyed the effective and appropriate performance temperature of silicon-based photovoltaic panels and provided an appropriate tabulation that helps the modeling and design process according to the solar energy's potential [51]. Ghiassi-Farrokhfal et al. assessed allocating a specific budget to solar panels and storage to maximize expected income. ...
Canada possesses significant potential in harnessing renewable energy from its vast and diverse geography, which can generate clean electricity. This paper presents a model that replaces fossil fuels used in a proposed thermal power plant in Point Aconi, Nova Scotia, with photovoltaic and wind turbine units based on the region’s climate conditions. The research results are based on evaluating multiple thermal power plants worldwide and examining various wind turbines and PV panels from different companies to ensure accuracy. The chosen units that best suit the location’s geographical and biological conditions, transmission, and operation costs demonstrate that the power plant currently consumes approximately 47 tons of coal and petroleum coke per hour. Replacing these materials with the proposed green units makes it possible to reduce environmental pollution by eliminating almost 165 tons of CO2 and other pollutants per hour while increasing the plant’s efficiency and independence from fossil fuel price variations. The presented structure’s ROI is approximately 20 years, which is reasonable compared to the economic and environmental benefits of utilizing such a structure and converting the thermal power plant to green units.
... Silicon photovoltaics (PV) demonstration a energy droplet above 25 °C panel heat with a temperature constant reaching since −0.3%/K up to −0.65%/K [1,2] dependent on category of PV cell and engineering knowledge [3]. Numerous scientific associations have been established to designate the requirement of PV functioning heat on climatical circumstances and PV resources [4]. The operative heat touched by PV panels and related energy droplet mainly related on the environment of the site. ...
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... The challenge in predicting temperature arises from the task of assessing the energy balance at the system level which necessitates the description of multiple heat modes with varying magnitudes. It is common practice to directly determine the temperature of the system as a function of environmental conditions [2]. However, this method is rarely reproducible as it assumes how energy transits from the PV system to the environment, so empirical temperature correlations have to be formulated for each PV installation geometry. ...
The temperature of photovoltaic (PV) cells is a critical factor in evaluating energy yield and predicting system
degradation. Although thermo-electrical models allows predicting the evolution of the system over time, precise
understanding of the thermal exchanges between the system and its environment is needed as they are
implemented in the yield assessment using thermal correlations. These empirical correlations are based on
heat transfer magnitudes undergone by similar PV set-ups.
The aim of this study is to introduce a non-intrusive experimental methodology for precisely determining
the convective heat transfer coefficient (CHTC) at the front of photovoltaic modules using two setups. The
method integrates a heat flux sensor glued to the PV surface coupled with environmental data (e.g., irradiance,
ambient temperature). This experimental method is applied to PV modules on a roof in an urban area and to
a floating photovoltaic (FPV) system. It is demonstrated that the method significantly improves the accuracy
of prediction of PV module temperatures in operating conditions compared to the conventional method based
on the energy balance of a PV module.
By using quantile regression, an empirical forced convection correlation is found based on the average
wind speed. Compared to the traditional approach which relies on global transmittance, the CHTC is mainly
dependent on the wind, whereas the global transmittance includes the radiative heat transfer which depends
on the module temperature. The correlation for CHTC tailored for the floating photovoltaic system shows
sensitivity to wind speed that is slightly higher compared to the inland setup in the literature.
... The second and third models are advanced models proposed by Skoplaki et al. [16], here called Skoplaki 1 and Skoplaki 2, respectively. As follows, they take wind data into account and both of them rely on expression 12. ...
... The value of the PVG operating temperature (T PVG (t)) used in the previous model can be estimated using the expression proposed in [29], and shown in Equation (4), where ...
The main objective of this work is to evaluate the energy efficiency improvement obtained in grid-connected photovoltaic systems based on a dynamic reconfiguration strategy. The MIX and team reconfigurable photovoltaic system topologies have been considered since both minimize the operation of the inverters in low-load conditions. A numerical method is used to analyze the energy flows within the photovoltaic system, with a specific focus on the plant-oriented configuration. In this work, MIX systems are only presented briefly, while team reconfigurable photovoltaic systems are analyzed in more detail. This is because team systems can be implemented using conventional commercial inverters, electromechanical switches to redirect power flows, and a simple digital controller (as based on the Arduino platforms). The energy supplied to the grid by two grid-connected photovoltaic systems will be evaluated: one based on a classic non-reconfigurable strategy and another based on the team strategy. The measurement of the energy generated by these two systems, tested under various irradiance levels (emulating different climatic conditions), shows that reconfigurable systems always exhibit greater energy efficiency. However, this energy improvement can only be considered substantial in certain situations.
... PV generation and building electricity consumption profiles serve as essential foundations for researching PVB systems. As for PV generation data, there are already mature empirical formulas [4,45] or commercial software [46,47] available for calculation. Furthermore, electricity consumption profiles also substantially impact the analysis results. ...
The widespread adoption of distributed photovoltaic (PV) systems is crucial for achieving a decarbonized future, and distributed energy storages play a vital role in promoting PV energy consumption and easing the grid burden. This study uses actual building electricity consumption data to examine the temporal and dimensional matching performance and economic feasibility of photovoltaic-battery (PVB) systems. When prioritizing nearly self-consumption, there is a knee point in the growth trend where the energy storage demand increases with the ratio of annual PV generation to annual electricity demand (R pv). Before this point, energy storage primarily serves intraday energy transfers. However, once R pv surpasses this point, there is a rapid surge in energy storage demand due to the requirement for cross-season energy transfer. When nearly self-sufficiency is desired, the energy storage demand experiences a rapid decrease to converge to a non-zero value as R pv increases. Comparative analyses reveal that public buildings with concentrated daytime electricity consumption and shopping malls in different climate zones with similar intraday usage patterns show comparable matching performance when equipped with short-term energy storage. However, as high self-consumption or self-sufficiency rates are pursued, variances in their seasonal consumption characteristics lead to significant differences in energy storage demand. From an economic perspective, integrating batteries into a shopping mall in Beijing increases the equivalent electricity price under the prevailing feed-in tariff. In addition, when surplus PV generation export is prohibited or unremunerated, the battery does not enhance the economic feasibility until R pv exceeds 51%, and partial curtailment of PV generation is economical when R pv exceeds 26%. Furthermore, to achieve a high self-sufficiency level, slightly expanding R pv beyond the required self-sufficiency rate can efficiently reduce energy storage demand and improve economic feasibility at the expense of partial curtailment of PV generation.
... The efficiency of PV cells declines with an increase in temperature. Crystalline silicon cells, a temperature coefficient ranging from − 0.3 to − 0.5%/°C is usual 73 . This means that for each degree Celsius rise in temperature, the efficiency of the solar cell decreases by that percentage. ...
The study elucidates the potential benefits of incorporating a BiI3 interfacial layer into perovskite solar cells (PSCs). Using MAPbI3 and MAGeI3 as active layers, complemented by the robust TiO2 and Spiro-OMeTAD as the charge-transport-layers, we employed the SCAPS-1D simulation tool for our investigations. Remarkably, the introduction of the BiI3 layer at the perovskite-HTL interface significantly enhanced hole extraction and effectively passivated defects. This approach minimized charge recombination and ion migration towards opposite electrodes, thus elevating device performance relative to conventional configurations. The efficiency witnessed a rise from 19.28 to 20.30% for MAPbI3 and from 11.90 to 15.57% for MAGeI3. Additionally, MAGeI3 based PSCs saw an improved fill-factor from 50.36 to 62.85%, and a better Jsc from 13.22 to 14.2 mA/cm², signifying reduced recombination and improved charge extraction. The FF for MAPbI3 based PSCs saw a minor decline, while the Voc slightly ascended from 1.24 to 1.25 V and Jsc from 20.01 to 21.6 mA/cm². A thorough evaluation of layer thickness, doping, and temperature further highlighted the critical role of the BiI3 layer for both perovskite variants. Our examination of bandgap alignments in devices with the BiI3 interfacial layer also offers valuable understanding into the mechanisms fueling the observed improvements.
... This explains the research focus on it. Skoplaki and Palyvos discussed in Ref. [20] the importance of solar cell operating temperature on the electrical performance of silicon-based PV installation and presented a review of formulations and correlations adequate to different installation situations. ...
Accurate estimation of photovoltaic (PV) panels’ temperature is crucial for an accurate assessment for both the electrical and thermal aspects and performances. In this study we propose an advanced simulation approach linking a double-diode (DD) electrical model using the Artificial hummingbird algorithm; for parameter extraction; and a two-dimensional finite-difference-based thermal model. The electrical-sub model is firstly validated in comparison to experimental data figuring in literature using three types of PV technologies, with a relative error of about 2%. Then, the coupled model is validated using in-situ experimental setup consisting of the usage of thin-film PV technology, temperature sensors, weather station and an infrared camera. The results from both simulations and experiments exhibit strong alignment with a relative error of not higher than 2%; mainly due to the used material calibration uncertainties and external perturbations. This holistic model can be indeed further optimized, still, it has a potential to advance the development in the research area of PV systems.Future efforts could involve additional experimentation to validate the model for different seasons of the year.
... Photovoltaic modules possessing a high U-value can effortlessly disperse their thermal energy. Equation (1) details the U-value calculation [35]. ...
Photovoltaic (PV) modules have emerged as a promising technology in the realm of sustainable energy solutions, specifically in the harnessing of solar energy. Photovoltaic modules, which use solar energy to generate electricity, are often used on terrestrial platforms. In recent years, there has been an increasing inclination towards the installation of photovoltaic (PV) modules over water surfaces, including lakes, reservoirs, and even oceans. The novel methodology introduces distinct benefits and complexities, specifically pertaining to the thermal characteristics of the modules. In order to accomplish this objective, a photovoltaic (PV) module system with a capacity of 1 MW was developed as a scenario in the PVsyst Program. The scenario simulation was conducted on the Mamasın Dam, situated in the Gökçe village within the Aksaray province. To conduct the efficiency analysis, a comparative evaluation was conducted between bifacial and monofacial modules, which were installed from above the water at 1 m. The comparison was made considering two different types of modules. Additionally, the albedo effect, water saving amount, and CO 2 emissions of the system were also investigated. Albedo measurements were made in summer when the PV power plant will operate most efficiently. As a result of the simulations, it was found that bifacial modules produce 12.4% more energy annually than monofacial modules due to the albedo effect. It is estimated that PV power plant installation will save 19,562.695 and 17,253.475 tons of CO 2 emissions in bifacial and monofacial systems, respectively.
... As BIPVs continue to evolve, it is even more necessary to improve the tools available for optimal electrical design and simulation of BIPV systems. This means correctly modeling the performance of such BIPV systems, which includes modeling the PV module temperature [14,15]. Appropriate standardization for assessing heat transfer and solar heat gains of BIPV modules still requires further development because BIPV elements behave differently from the building elements they replace. ...
Citation: Barbusiński, K.; Kwaśnicki, P.; Gronba-Chyła, A.; Generowicz, A.; Ciuła, J.; Szeląg, B.; Fatone, F.; Makara, A.; Kowalski, Z. Influence of Environmental Conditions on the Electrical Parameters of Side Connectors in Glass-Glass Photovoltaic Modules. Energies 2024, 17, 680. https://doi.org/10.3390/ en17030680 Academic Editor: Frede Blaabjerg Abstract: This work focused on the verification of the electrical parameters and the durability of side connectors installed in glass-glass photovoltaic modules. Ensuring the safe use of photovoltaic modules is achieved, among others, by using electrical connectors connecting the PV cell circuit inside the laminate with an external electric cable. In most of the cases for standard PV modules, the electrical connector in the form of a junction box is attached from the back side of the PV module. The junction box is glued to the module surface with silicone where the busbars were previously brought out of the laminate through specially prepared holes. An alternative method is to place connectors on the edge of the module, laminating part of it. In such a case, the specially prepared "wings" of the connector are tightly and permanently connected using laminating foil, between two glass panes protecting against an electrical breakdown. Additionally, this approach eliminates the process of preparing holes on the back side of the module, which is especially complicated and time-consuming in the case of glass-glass modules. Moreover, side connectors are desirable in BIPV applications because they allow for a more flexible design of installations on façades and walls of buildings. A series of samples were prepared in the form of PV G-G modules with side connectors, which were then subjected to testing the connectors for the influence of environmental conditions. All samples were characterized before and after the effect of environmental conditions according to PN-EN-61215-2 standards. Insulation resistance tests were performed in dry and wet conditions, ensuring full contact of the tested sample with water. For all modules, before being placed in the climatic chamber, the resistance values were far above the minimum value required by the standards, allowing the module to be safely used. For the dry tests, the resistance values were in the range of GΩ, while for the wet tests, the obtained values were in the range of MΩ. In further work, the modules were subjected to environmental influences in accordance with MQT-11, MQT-12, and MQT-13 and then subjected to electrical measurements again. A simulation of the impact of changing climatic conditions on the module test showed that the insulation resistance value is reduced by an order of magnitude for both the dry and wet tests. Additionally, one can observe visual changes where the lamination foil is in contact with the connector. The measurements carried out in this work show the Energies 2024, 17, 680. https://doi.org/10.3390/en17030680 https://www.mdpi.com/journal/energies Energies 2024, 17, 680 2 of 13 potential of side connectors and their advantage over rear junction boxes, but also the technological challenges that need to be overcome.
... To minimize the impact of heat on the solar panel, technical solutions can be used, such as the installation of a cooling system, ventilation, or the use of special materials and coatings that allow more efficient heat capture and removal. It is also important to install the panel correctly, preventing it from being heated by sunlight or the proximity of other heat sources [9][10]. ...
Thermal effects on a solar panel can have both positive and negative effects on its operation and efficiency. Under the influence of solar radiation, the panel heats up. This leads to a lower performance and a shorter service life. The article studies the change in temperature and radiation on the surface of solar panels standing in the shadow of a building and an unshaded place.
... silício cristalino e filmes finos de CIGS) ou menor (e.g. filmes finos de silício amorfo e CdTe) (Skoplaki e Palyvos, 2009ae 2009b. É possível observar que a temperatura tem influência negativa considerável tanto na tensão de operação como na potência, ou seja, em condições normais de operação (entre 30 e 75 °C), o módulo FV irá operar com níveis de tensão e potência menores do que os nominais nas condições de teste (Gueymard et al., 2002). ...
Este trabalho tem por objetivo analisar a produção energética e o desempenho de sistemas fotovoltaicos distribuídos em seis tecnologias distintas, instalados no Módulo de Avaliação (MA) de Itiquira, localizado no estado do Mato Grosso e comparar a produção energética e o desempenho obtidos através da aquisição de dados em campo com os obtidos através de simulação computacional via software PVSyst. Os resultados mostram que a simulação computacional superestimou, em média, os valores anuais de desempenho global em 5,4 %. Para o sistema estudado e para o período analisado a tecnologia a-Si foi a que apresentou melhor desempenho quando comparada com as demais tecnologias. Para o período analisado, a geração fotovoltaica e a produtividade obtidas por simulações via PVSyst foram, em média, 6,6 % maiores que os resultados obtidos através de valores medidos no MA-Itiquira. A tecnologia a-Si apresentou menor diferença percentual (1,4%) entre a geração fotovoltaica obtida por simulação e a obtida através de valores medidos e a tecnologia m-Si apresentou a maior diferença percentual (11,4%) entre a geração fotovoltaica obtida por simulação e a obtida através de valores medidos. Palavras-chave: Energia solar fotovoltaica, Geração fotovoltaica, Fatores de desempenho 1. INTRODUÇÃO A irradiação solar no Brasil possui pequena variabilidade anual e sua distribuição é uniforme, além de possuir um dos maiores índices do mundo. Devido as proporções continentais do território brasileiro, a perturbação da atmosfera e os fenômenos climáticos variam em diferentes locais (Martins et al., 2007). O nível médio anual de irradiação solar global horizontal no município de Itiquira-MT (17,2° S, 54,15° O) é de 5,168 kWh/m² (Pereira et. al., 2017). A energia solar fotovoltaica (FV) tem apresentado uma grande evolução desde o início de sua história e é atualmente a tecnologia de geração de energia de mais rápido crescimento em todo o mundo (REN21, 2014). Incentivos financeiros devem ser disponibilizados para promover a redução do investimento inicial da geração de energia solar fotovoltaica, tornando esta tecnologia competitiva, especialmente quando comparado com tarifas residenciais (Lacchini e Rüther, 2015; Rüther e Zilles, 2011; Silveira et al., 2013). Apesar de grande parte da energia de um sistema FV ser gerada sob altos níveis de irradiância (Burger e Rüther, 2006), dependendo da época do ano e do índice de nebulosidade, baixas irradiâncias podem ter grande influência no desempenho do sistema FV (Rüther et al., 2010). Pode-se observar que a tecnologia FV de silício amorfo (a-Si) atinge eficiência nominal para praticamente qualquer nível de irradiância, enquanto que as outras tecnologias FV apenas apresentam eficiência próxima da nominal em irradiâncias superiores a aproximadamente 300 W/m² (Reich et al., 2005). O desempenho de um sistema FV é tipicamente medido pela Performance Ratio (PR), que é definida como a relação entre o desempenho real do sistema e o máximo desempenho teórico possível, pois contabiliza todas as perdas envolvidas no sistema, como perdas por queda de tensão devido à resistência elétrica de condutores e conectores, além das perdas por sujeira, eficiência do inversor, temperatura de operação dos módulos FV, entre outras. A PR possibilita comparar sistemas FV instalados em locais e/ou orientações diferentes e avaliar sua geração de energia elétrica (Marion et al., 2005). A temperatura ambiente desempenha um papel importante na análise de desempenho de um sistema FV. Além disso, existe uma proporcionalidade direta entre a eficiência do sistema e a temperatura ambiente da localidade (Bhattacharya et al., 2014; Kaldellis et al., 2014). Dependendo da tecnologia FV, a influência da temperatura será maior (e.g. silício cristalino e filmes finos de CIGS) ou menor (e.g. filmes finos de silício amorfo e CdTe) (Skoplaki e Palyvos, 2009a e 2009b). É possível observar que a temperatura tem influência negativa considerável tanto na tensão de operação como na potência, ou seja, em condições normais de operação (entre 30 e 75 °C), o módulo FV irá operar com níveis de tensão e potência menores do que os nominais nas condições de teste (Gueymard et al., 2002). Outro fator
... CES included the following: (i) EP a per surface area of the PV field as a whole, including rows of soil between panels and infrastructure (EP a of ∼123 kWh m −2 year −1 in our study site). This is mostly determined by the efficiency of the entire PV field (PV eff = 5.8%) and includes losses due to the PV PR (i.e. the DC-AC current inverter, losses due to cables and transformers, and temperature-related efficiency decreases (93)) and the field cover parcel of the PV panels (43% in our case). (ii) The CF (i.e. ...
Suppression of carbon emissions through photovoltaic (PV) energy and carbon sequestration through afforestation provides complementary climate change mitigation (CCM) strategies. However, a quantification of the “break-even time” (BET) required to offset the warming impacts of the reduced surface reflectivity of incoming solar radiation (albedo effect) is needed, though seldom accounted for in CCM strategies. Here, we quantify the CCM potential of PV fields and afforestation, considering atmospheric carbon reductions, solar panel life cycle analysis (LCA), surface energy balance, and land area required across different climatic zones, with a focus on drylands, which offer the main remaining land area reserves for forestation aiming climate change mitigation (Rohatyn S, Yakir D, Rotenberg E, Carmel Y. Limited climate change mitigation potential through forestation of the vast dryland regions. 2022. Science 377:1436–1439). Results indicate a BET of PV fields of ∼2.5 years but >50× longer for dryland afforestation, even though the latter is more efficient at surface heat dissipation and local surface cooling. Furthermore, PV is ∼100× more efficient in atmospheric carbon mitigation. While the relative efficiency of afforestation compared with PV fields significantly increases in more mesic climates, PV field BET is still ∼20× faster than in afforestation, and land area required greatly exceeds availability for tree planting in a sufficient scale. Although this analysis focusing purely on the climatic radiative forcing perspective quantified an unambiguous advantage for the PV strategy over afforestation, both approaches must be combined and complementary, depending on climate zone, since forests provide crucial ecosystem, climate regulation, and even social services.
... O modelo proposto por Ross (1976) é uma função da temperatura ambiente, irradiância e de um parâmetro construtivo chamado de coeficiente de Ross (k), que pode variar entre 0,02 a 0,04 cm²/W (Skoplaki et al. 2009), cujo valor é descrito por (1). A Fig. 3 apresenta a diferença entre a temperatura ambiente e a temperatura do módulo, em função da irradiação solar, para dois tipos de módulos fotovoltaicos. ...
The power generated by PV arrays is directly associated with climatic conditions of the site of installation, through incident solar irradiance, ambient temperature and wind speed being the parameters that most affect their power generation. Therefore, it is evident that carrying out studies to better understand the influence of these parameters on generation is extremely important. It is known that the greater the incident solar irradiance, the greater PV module output power. High ambient temperatures causes an increase in module temperature, resulting in a decrease in power generation. The PV module temperature depends on numerous factors, which makes its estimation a very complex task. With the objective of increasing the quality and precision of this estimation, several authors have developed mathematical models that relate the cell operating temperature with the meteorological parameters. To evaluate the key characteristics that affect PV module temperature, this paper proposes a survey and comparison of the main mathematical models for estimating the operating temperature of PV arrays, found in literature. A model based on the average values of the evaluated methods is also proposed.
... This is, among other reasons, due to the critical dependence of the PV yield on temperature [1]- [8]. Thus, module temperature prediction attracts considerable research interests in the recent decade [9]- [14]. Moreover, two important quantities in photovoltaics: the Climatic Energy Rating of PV modules (CSER) according to International Electrotechnical Commission (IEC) 61853-3 standard series [15] and the Nominal Module Operating Temperature (NMOT) [16], [17] require an accurate module temperature prediction. ...
... Review of some studies on module temperature and efficiencies for floating solar PV compared to terrestrial PV. Estimate ground and floating PV panels output efficiencies Temperature plays a central role in the photovoltaic (PV) conversionprocess; due to an operating temperature increase of above 25 °Chas a negative effect on the electrical efficiency of PV modules, whoserate of change can be expressed in the function of this parameter bymeans of a large number of correlations that can be found in the literature [20]. ...
... Although the power (Wp) is the characteristic by which a module is identified, its effectiveness and energy production are intrinsically linked to external elements. These factors include the operating temperature of the cells, the presence of dirt on the surface of the modules, the amount of solar radiation received, and exposure to wind action [22]. ...
The purpose of this study is to employ and improve evolutionary algorithms, namely the genetic algorithm (GA) and the differential evolution algorithm (DE), to extract the parameters of the equivalent circuit model (ECM) of a bifacial photovoltaic module using the representative model of a diode with five parameters (1D5P). The objective is to simulate the characteristics of the I–V curves for various irradiation and temperature scenarios. A distinctive feature of this study is the exclusive use of the information in the technical sheet of the bifacial module to conduct the entire extraction and simulation process, eliminating the need to resort to external sources of data or experimental data. To validate the methods, a comparison was made between the simulation results and the data provided by the bifacial module manufacturer, contemplating different scenarios of irradiation and temperature. The DE was the most accurate algorithm for the 1D5P model, which presented a maximum average error of 1.57%. In comparison, the GA presented a maximum average error of 1.98% in the most distant scenario of STC conditions. Despite the errors inherent to the simulations, none of the algorithms presented relative errors greater than 8%, which represents a satisfactory modeling for the different operational conditions of the bifacial photovoltaic modules.
... Many proposed models for PV cell temperature prediction have been extensively validated against experimental data. Skoplaki and Playvos [50] reviewed approximately 40 correlations, implicit and explicit, for calculating operating temperatures. These correlations involve environmental variables and numerical parameters, which are material and/or system dependent. ...
... where V t is the voltage at a particular timestamp t, V OC,STC is the open circuit voltage under STC, γ is the temperature coefficient of MPP power, T mod ,t is the real time module temperature, and T STC is the STC temperature (room temperature). For practical reasons, T mod ,t can be estimated from ambient temperature and irradiance based on a well-established module temperature model [12], [13]. Due to incomplete knowledge of array V OC,STC for many sites used in this study, it is taken to be 1000 V for simplicity. ...
Underperformances in PV solar farms pose great risks to project returns and financial health. It is important to adopt proactive asset management and O&M practices to ensure good performance. Among the various possible causes of underperformance, those due to external factors such as snow, soiling, and extraordinary shading from vegetation growth can usually be mitigated. However, there is a lack of cost effective and reliable method to detect these phenomena. In this work, we explore the possibility of utilizing inverter MPPT voltage readings available from common SCADA and monitoring systems to detect vegetation shading. It is found that vegetation shading can cause significant deviation in voltage characteristics. This includes increased discrepancy among MPPT inputs, decrease in voltage level, and excessive voltage fluctuation under clear sky. Based on these signature patterns, it is possible to design algorithms to detect vegetation growth episodes and issue performance alerts to remote operators.
... To this end, estimation of the solar cell temperature is essential. Various approaches are introduced for that and extensive reviews can be found in [26,27,28]. Ambient temperature is one obvious factor in this. ...
... To this end, estimation of the solar cell temperature is essential. Various approaches are introduced for that and extensive reviews can be found in [26,27,28]. Ambient temperature is one obvious factor in this. ...
... To this end, estimation of the solar cell temperature is essential. Various approaches are introduced for that and extensive reviews can be found in [26,27,28]. Ambient temperature is one obvious factor in this. ...
... To this end, estimation of the solar cell temperature is essential. Various approaches are introduced for that and extensive reviews can be found in [26,27,28]. Ambient temperature is one obvious factor in this. ...
The Increase in temperature of PV cells leads to a notable fall in their electrical efficiency, which is known as a major fault of photovoltaic (PV) panels. Among several methods in cooling PV cells, this article deals with aimed to study the effect of two fin arrays, i.e. straight and wavy. Each one has been tested in two various numbers of and, with and without wind blow of 2 km/h. Experiments were performed by a solar-simulator, under constant irradiation of 700 W/m2. According to the temperature results, employing wavy fins due to its greater contact area showed lower temperature than straight fins. So that using 10 wavy fins leads to keep the temperature of PV panel 7 ͦ C lower than those of 10 straight fins. From an electrical efficiency point of view, installing 20 wavy fins shows 2% more value than the base case. Furthermore, both PV cell temperature and electrical efficiency for all cases were calculated by means of empirical and analytical equations, too, and a good agreement was illustrated with the experimental findings of this research. Finally, annual reduction in CO2 emission as an important environmental aspect was calculated by means of RETScreen software.
The development of a transient temperature model of photovoltaic (PV) modules is presented in this paper. Currently, there are a few steady‐state temperature models targeted at assessing and predicting the PV module temperature. One of the most commonly used models is the Faiman thermal model. This model is derived from the modified Hottel‐Whillier‐Bliss (HWB) model for flat‐plate solar‐thermal collector under steady‐state conditions and assumes low or no thermal mass in the modules (i.e., short time constants such that transients are neglected, and steady‐state conditions are assumed). The transient extension of the Faiman model we present in this paper introduces a thermal mass, which provides two advantages. First of all, it improves the temperature prediction under dynamic conditions. Second, our transient extension to the Faiman model allows the accurate parametrization of the Faiman model under dynamic conditions. We present our model and parametrization method. Furthermore, we applied the model and parametrization method to a 1‐year data set with 5‐min resolved outdoor module measurements. We demonstrate a significant improvement in temperature prediction for the transient model, especially under dynamic conditions.
A novel PV/T-PCM system was designed and fabricated to conduct a detailed experimental analysis of each of the cooling methods used on the performance of PV panel in the form of temperature and electrical efficiency of the panel. Empirical correlations were also developed to predict the electrical efficiency and PV panel surface temperature using the experimental data of present investigation considering investigated system and operating parameters.
In the realm of renewable energy systems, the effective selection of Photovoltaic Thermal (PVT) collectors is important. This study delves into the intricacies of choosing optimal PVT collectors available in the market, emphasizing the utility of Multiple Criteria Decision Making (MCDM) methodologies. PVT collectors are differentiated based on various aspects such as their transparent front cover presence and the medium—liquid or air—used for heat transfer. The study methodologically identifies commercially available PVT collectors and establishes key performance indicators for comparison. Using an 11-point fuzzy scale, a weight matrix is determined. Subsequently, advanced MCDM techniques, including PROMETHEE II, TOPSIS, EDAS, and VIKOR, are employed to rank the alternatives. This research not only provides a systematic approach to PVT collector selection but also extends to a MATLAB-based tool for facilitating the process. The results underscore the value of the proposed methodologies in refining the selection of PVT collectors and their potential adaptability to other applications, such as PVT collector design.
Owing to the persisting hype in pushing toward global carbon neutrality, the study scope of atmospheric science is rapidly expanding. Among numerous trending topics, energy meteorology has been attracting the most attention hitherto. One essential skill of solar energy meteorologists is solar power curve modeling, which seeks to map irradiance and auxiliary weather variables to solar power, by statistical and/or physical means. In this regard, this tutorial review aims to deliver a complete overview of those fundamental scientific and engineering principles pertaining to the solar power curve. Solar power curves can be modeled in two primary ways, one of regression and the other of model chain. Both classes of modeling approaches, alongside their hybridization and probabilistic extensions, which allow accuracy improvement and uncertainty quantification, are scrutinized and contrasted thoroughly in this review.
Forecasting plays an indispensable role in the grid integration of solar energy, which is an important pathway toward the grand goal of achieving planetary carbon neutrality. This rather specialized field of solar forecasting constitutes both irradiance and photovoltaic power forecasting. Its dependence on atmospheric sciences and implications for power system operations and planning make the multi-disciplinary nature of solar forecasting immediately obvious. Advances in solar forecasting represent a quiet revolution, as the landscape of solar forecasting research and practice has dramatically advanced as compared to just a decade ago.
Solar Irradiance and Photovoltaic Power Forecasting provides the reader with a holistic view of all major aspects of solar forecasting: the philosophy, statistical preliminaries, data and software, base forecasting methods, post-processing techniques, forecast verification tools, irradiance-to-power conversion sequences, and the hierarchical forecasting and firm forecasting frameworks. The book’s scope and subject matter are designed to help anyone entering the field or wishing to stay current in understanding solar forecasting theory and applications. The text provides concrete and honest advice, methodological details and algorithms, and broader perspectives for solar forecasting.
En este trabajo se propone una metodología para estimar el valor de energía generado por un módulo FV cualquiera, inclinado y orientado, bajo condiciones estadísticamente representativas de radiación solar y temperatura ambiente, en la ciudad de Salta (Argentina). Para ello primero se prepara una base de datos de irradiancia solar global y de temperatura ambiente estadísticamente representativa para el sitio, utilizando un procedimiento de Adaptación al Sitio mejorado, usando datos medidos en el sitio especifico. Se aplica luego el modelo de Engerer para estimar la fracción difusa con lo que se estima la componente directa y difusa de la irradiancia solar global, considerando los aportes de cada componente sobre el plano del módulo. Se aplican estos datos a un modelo de modulo FV basado en diferencia de valores de potencia eléctrica STC afectado por temperatura de modulo. La diferencia de los valores GHI anuales adaptados y sin adaptar es del 8.35%, lo que genera una diferencia del 7.34% en la energía eléctrica generada por un módulo de 450 Wp y 2.21 m2 de área, inclinado 24° y orientado al norte. Este procedimiento es el primer paso para generar una herramienta que permita estimar la generación FV domiciliaria en la ciudad de Salta, y posteriormente la previsión de producción.
The power output of a photovoltaic system is dependent on the operating temperature of the solar cells. For floating PV (FPV), increased wind speeds can result in increased yield due to lowered operating temperatures, which has long been stated as a key advantage for FPV. So far, this effect has not been included in commercial software packages for yield estimation. Typically, only standard settings are provided, taking into account the mounting type (PVsyst) or mounting and module type (Sandia). This may result in an underestimation of the yield, and consequently, the estimated Levelized Cost of Electricity (LCOE) of the FPV project. In this study, a linkage between recorded module temperatures from FPV systems located in The Netherlands and Sri Lanka and the prevalent models employed within PVsyst and Sandia software for estimating module temperatures are established. Our findings reveal that the models within PVsyst and Sandia tend to overestimate module temperatures by 2.4% and 3%, respectively, for each 1 m/s increment in wind speed. We present two methods for determining the single heat loss coefficient, or U-value, tailored to specific sites accounting for local wind conditions. The first method computes the U-value based on the average monthly wind speed, whereas the second employs the irradiance-weighted average monthly wind speed. The latter method can be advantageous for locations characterized by significant fluctuations in wind speeds between night and day. Through a statistical residual analysis comparing measured and modeled module temperatures, we demonstrate that our proposed methods offer a more accurate representation of module temperature compared to the PVsyst and Sandia models when default settings are used. When we subsequently compute the specific yield using both measured and modeled temperatures, we observe that the approach using irradiance-weighted average wind speed shows a higher yield of up to 2% compared to the traditional methods.
Розробка багатофункціональних сонячних систем, до яких відносяться безпосередньо PV/T системи та системи тепло- холодопостачання і кондиціювання повітря, їх впровадження в вітчизняне виробництво буде сприяти зменшенню залежності нашої країни від невідновлюваних паливно-енергетичних ресурсів, створенню нових виробництв та робочих місць. Розглядається стан розробок сонячних полігенераційних PV/T систем, можливість поширення в житловому секторі та готовність власників комунальних домогосподарств до модернізації систем опалення та електропостачання. Відзначається, що поліенерація електроенергії, холоду та теплоти, забезпечуючи повну автономність сонячних систем, здатна вирішувати основні завдання життєзабезпечення: гарячого водопостачання, охолодження середовищ та кондиціювання, а також осушення повітря для застосування у різних технологічних процесах виробництва. Наведені дані щодо перспектив сумісного використання сонячних повітряних колекторів з системами опалення та вентиляції. Розглядається сучасний стан практичного застосування PV/T-колекторів. Відзначаються причини, що заважають швидкому поширенню PV/T систем та порівнюється ефективність колекторів різного конструктивного виконання. Представлені конструктивні та функціональні особливості роботи когенераційної сонячної електротеплової станції та оцінка її ефективності відносно економії невідновлювальних джерел. Наведена оцінка ринкового потенціалу колекторів PV/T. Наголошується, що, оскільки споживачі використовують найбільшу кількість енергії для опалення, сонячний колектор PV/T є альтернативною перспективною системою для низькоенергетичних застосувань у житлових, промислових та комерційних будівлях. Представлено концепцію створення нового покоління багатофункціональних геліосистем на основі тепловикористовувального абсорбційного циклу відкритого типу
A barrier to the widespread application of building integrated photovoltaics (BIPV) is the lack of validated predictive performance tools. Architects and building owners need these tools in order to determine if the potential energy savings realized from building integrated photovoltaics justifies the additional capital expenditure. The National Institute of Standards and Technology (NIST) seeks to provide high quality experimental data that can be used to develop and validate these predictive performance tools. The temperature of a photovoltaic module affects its electrical output characteristics and efficiency. Traditionally, the temperature of solar cells has been characterized using the nominal operating cell temperature (NOCT), which can be used in conjunction with a calculation procedure to predict the module's temperature for various environmental conditions. The NOCT procedure provides a representative prediction of the cell temperature, specifically for the ubiquitous rack-mounted installation. The procedure estimates the cell temperature based on the ambient temperature and the solar irradiance. It makes the approximation that the overall heat loss coefficient is constant. In other words, the temperature difference between the panel and the environment is linearly related to the heat flux on the panels (solar irradiance). The heat transfer characteristics of a rack-mounted PV module and a BIPV module can be quite different. The manner in which the module is installed within the building envelope influences the cell's operating temperature. Unlike rack-mounted modules, the two sides of the modules may be subjected to significantly different environmental conditions. This paper presents a new technique to compute the operating temperature of cells within building integrated photovoltaic modules using a one-dimensional transient heat transfer model. The resulting predictions are compared to measured BIPV cell temperatures for two single crystalline BIPV panels (one insulated panel and one uninsulated panel). Finally, the results are compared to predictions using the NOCT technique.
Solar energy can be converted to electrical energy by means of two methods: the first one is a direct method with photovoltaic (PV) systems and the second is an indirect one by solar thermal power generation. The main disadvantage of the PV systems is the high sensitivity of the output electrical characteristics to their temperature surface. The increase of the surface temperature leads to reduce the power output according to its power temperature coefficient. For this purpose we have to locate the zones where the PV systems can work efficiently as high as the standard test condition (STC) efficiency. The aim of this research is to determine the surface cell temperature of a working PV system under real operational and environmental conditions (Load, Solar radiation and ambient), further to evaluate the electrical behavior of PV systems and to estimate the failure of their function. The experiment has been carried out in order to measure the following parameters: output power, surface temperature, solar radiation, ambient temperature and wind speed. An experimental model has been designed and built up in the Solar Energy Laboratory at the Department of Mechanical Engineering, in Brack. Brack City is located at 27.6°N and 14.2°E, 600 km away to the south from Tripoli (Capital). According to the results of the experiment, the maximum cell's surface temperature reached 125.4°C in 6/5/2003 at 2:30 PM. The solar radiation was around 896 W/m2. The percent of the failure of the power was found to be 69% of the nominal power at STC. This is why we have to be careful concerning the use of PV cells for Multi-Mega-Watts power generation, especially, which classified as hot regions, in most of the Arabic countries, especially in those which are classified as hot regions, such as North Africa and South Asia.
This paper describes a new one-diode equivalent photovoltaic (PV) model that has been implemented into the ESP-r simulation program. The validation of this model, as well as that of ESP-r's existing one-diode model, is also treated. Specifically, the PV arrays installed at a laboratory facility at CETC-Varennes are modelled using both models and the simulation results are compared to monitored data. The monitored data include the weather conditions at the site, the direct- current power generated by the PV modules and the temperature of the modules.
The report outlines the short-term field testing used by Building America staff and includes a report on the results of an example test of a PV system with battery storage on a home in Tucson, Arizona. This report is not intended as a general recommended test procedure for wide distribution. It is intended to document current practices in Building America to inform program stakeholders and stimulate further discussion. Building America staff intend to apply this procedure until relevant standards for testing PV modules are completed.
Most of the absorbed solar radiation by solar cells is not converted into electricity it increases their temperature, reducing their electrical efficiency. The PV temperature can be lowered by heat extraction with a proper natural or forced fluid circulation. An interesting alternative to plain PV modules is to use Hybrid Photovoltaic/Thermal (PV/T) systems, which consist of PV modules coupled to heat extraction devices, providing electricity and heat simultaneously. Hybrid PV/T systems are of higher cost than standard PV modules because of the addition of the thermal unit and therefore a cost/benefit analysis is needed to find out the limits of practical use of these. A couple of typical applications are selected in order to assess the benefits for the users of hybrid PV/T systems comparing the payback time with PV systems and Solar thermal ones, under the current support schemes and conditions in Greece. A spreadsheet was developed that calculates on an hourly basis the annual energy output of the different systems. Furthermore, the energy output and the estimated system costs per surface area are introduced in an economic analysis spreadsheet, where the payback time for each system is calculated.
To date, many traditional Solar Home Systems (SHS) have consisted of separate components requiring assembly by trained individuals in the field. While this cannot be secured, many SHSs in remote areas have not fulfilled their expected lifecycles or have not functioned at all. The new Integrated Solar Home System (I-SHS) offers a solution: All components such as PV module, charge controller, inverter and wiring, but also support structure and foundation, are integrated and pre-assembled by the manufacturer. This eases installation and reduces costs and failures. Additionally, through the integration of a water tank that serves as a cooling unit as well as the system foundation, a significant reduction of operating cell temperature was achieved, increasing electrical yield by 9–12%.
Through integration of a water tank that serves as a cooling unit as well as the system's foundation, a significant reduction of operating cell temperature was achieved, thus increasing PV conversion efficiency and electrical energy yield by 9-12%. All components such as PV module, charge controller, inverter and wiring, but also support structure and foundation, are integrated and pre-assembled by the manufacturer. This eases installation, operation ("Plug & Play"), reduces costs and failures, thus increasing reliability and confidence in PV power generation. During development of the Integrated Solar Home System (I-SHS), water volume of the tank above the PV module has been increased, allowing additional storage of hot water in the upper part, thus further reducing PV operating temperature, increasing output voltage and enabling the use of a module with a reduced number of solar cells in series connection (e.g. 32 instead of 36 cells). The power condition units and the battery are now placed in the center of the cooling device, reducing their operating temperatures and increasing lifetime. Once placed at an appropriate site the I-SHS is immediately able to supply small AC loads (lights, fan, radio, TV, DVD, CD, computer etc.). Featuring favorable Balance of System Costs (BOS) and the generation of more energy, the enhanced I-SHS is an efficient means to electrify remote areas, but also serves as a compact PV device for urban flat roofs. A new version of the system is equipped with an electricity metering device monitored via satellite and a payment unit to facilitate refinance of the system.
Presented at the 2001 NCPV Program Review Meeting: Describes the latest version of PVWATTS and how its spatial resolution was improved by a factor of 25. This paper describes the latest version of PVWATTS and how its spatial resolution was improved by a factor of 25 by using a high-resolution (e.g., 40-km by 40-km cells) spatially uniform grid of meteorological input data. Like its predecessor, version 2 is Internet accessible. The user selects a grid cell containing the desired location from an electronic map, thereby initiating a selection by PVWATTS v.2 of the nearest TMY2 station that is climatically similar, followed by an hourly performance simulation for the TMY2 station. Performance is translated back to the selected grid cell based on differences in solar radiation and temperature using previously determined data grid sets of monthly solar radiation and maximum daily temperature.
A new method has been proposed [W. Durisch, K.H. Lam, J. Close, Behaviour of a copper indium gallium diselenide module under real operating conditions, in: Proceedings of the World Renewable Energy Congress VII, Pergamon Press, Oxford, Elsevier, Amsterdam, 2002, ISBN 0-08-044079-7] for the calculation of the annual yield of photovoltaic (PV) modules at selected sites, using site-specific meteorological data. These yields are indispensable for calculating the expected cost of electricity generation for different modules, thus allowing the type of module to be selected with the highest yield-to-cost ratio for a specific installation site. The efficiency model developed and used for calculating the yields takes three independent variables into account: cell temperature, solar irradiance and relative air mass. Open parameters of the model for a selected module are obtained from current/voltage (I/V) characteristics, measured outdoors at Paul Scherrer Institute's test facility under real operating conditions. From the model, cell and module efficiencies can be calculated under all relevant operating conditions. Yield calculations were performed for five commercial modules (BP Solar BP 585 F, Kyocera LA361K54S, Uni-Solar UPM-US-30, Siemens CIS ST40 and Wuerth WS11003) for a sunny site in Jordan (Al Qawairah) for which reliable measured meteorological data are available. These represent mono-crystalline, poly-crystalline and amorphous silicon as well as with copper–indium-diselenide, CuInSe2 PV modules. The annual yield for these modules will be presented and discussed.
The Matrix and Performance Surface Methods of Energy Rating are related techniques under development for the determination of electrical yield that is intended to be a more useful predictor of performance for installers than W<sub>p</sub> alone. Here a power matrix or performance surface as a function of irradiance and ambient temperature P(G<sub>i</sub>; T<sub>a</sub>) is linked to a climatic condition occurrence matrix N(G<sub>i</sub>, T<sub>a</sub>) for a particular location. The use of just two independent variables has the advantage of simplicity but it is important to evaluate the possible cost of reduced accuracy due to the exclusion of other variable parameters such as Air Mass for example. The power matrix may be determined by outdoor or indoor measurements, and the complete matrix may also be extrapolated from a reduced data set using models of cell behaviour thereby reducing measurement time. The present paper relates solely to crystalline Si and reports on the comparison of outdoor measurements at two sites, and their further comparison with indoor measurements.
The photovoltaic cells current–voltage mathematical description is usually defined by a coupled nonlinear equation, difficult to solve using analytical methods. This paper investigates a modeling process configuring a computer simulation model, able to demonstrate the cell's output features in terms of irradiance and temperature environment changes. The model is based on four parameters, and it is tested to simulate three popular types of photovoltaic panels constructed with different materials: copper indium diselenide (CIS) thin film, multi-crystalline silicon, and mono-crystalline silicon. A comparative study of simulation results, carried out by the product manufacturer data, is provided to prove the efficiency of the proposed approach.
The Photovoltaic Engineering Handbook is the first book to look closely at the practical problems involved in evaluating and setting up a photovoltaic (PV) power system. The author’s comprehensive knowledge of the subject provides a wealth of theoretical and practical insight into the different procedures and decisions that designers need to make. Unique in its coverage, the book presents technical information in a concise and simple way to enable engineers from a wide range of backgrounds to initiate, assess, analyze, and design a PV system. It is beneficial for energy planners making decisions on the most appropriate system for specific needs, PV applications engineers, and anyone confronting the practical difficulties of setting up a PV power system.
Using a simplified model for the heat exchange between a photovoltaic module and his environment we determine coefficients to calculate the cell operating temperature from the measurements of climatic parameters.
The article analyzes the effect of resistance of the switching cable and blocking diode on the stability of a power supply system's optimum voltage with a change in ambient temperature and the level of illumination. It is shown that there is a region of values of switching elements' relative resistance which should be avoided in designing photovoltaic systems.
A complete overview of solar technologies relevant to the built environment, including solar thermal energy for heating and cooling, passive solar energy for daylighting and heating supply, and photovoltaics for electricity production. Provides practical examples and calculations to enable component and system simulation e.g. Calculation of U-values, I-V curve parameters and radiance distribution modelling. Discusses the new trends in thermal energy use, including the architectural integration of collector systems, integrated ventilation photovoltaics facades and solar powered absorption cooling systems. Coverage of cutting-edge applications such as active and passive cooling techniques and results from ongoing research projects.
The output from the photovoltaic (PV) generator depends on solar radiation incident on the inclined panels of the PV array. In some applications, the array orientation will be constrained by the nature of the support system: For example, the orientation of a building-integrated array will normally be dictated by the orientation of the roof or facade, where the array is to be installed. For a freestanding PV array, the most important consideration in deciding the array orientation is to maximize the energy collection by the inclined PV panels. This will frequently depend on the seasonal nature of the load. PV arrays that track the sun can collect a higher amount of energy than do those installed at a fixed tilt. The use of tracking is common for concentrator arrays—at least for appreciable concentration ratios—collect only the direct (beam) radiation. It is seen that, on a yearly basis, the energy capture by a tracking flat-plate system is increased by more than 30% over a fixed array at latitude inclination. At the same time however, that a tracking concentrator system will collect more energy than will a hat-plate system only in locations with predominantly clear skies.
The evaluation and assessment of the performance of photovoltaic (PV) cells requires the measurement of the current as a function of voltage, temperature, intensity, wind speed and radiation spectrum. Most noticeable of these parameters is the PV conversion efficiency η (defined as the maximum electrical power Pmax produced by the PV cell divided by the incident photon power Pin) which is measured with respect to standard test conditions (STC). These conditions refer to the solar spectrum , solar radiation intensity , cell temperature and wind speed (2 mph). Tests under STC are carried out in laboratory-controlled environment.With an increase of ambient temperature, there is a deficiency in the electrical energy that the solar cell can supply. This situation is especially important in hot climates. Outdoor exposure tests of solar cells have been conducted in the Department of Physics, University of Brunei Darussalam. Preliminary results demonstrate that the efficiency of the single crystal silicon solar cell strongly depends on its operating temperature. It has been noted that at the operating temperature of 64 °C, there was a decrease of 69% in the efficiency of the solar cell compared with that measured at STC. Investigation of the effect of variation in intensities of sunlight on the solar cell performance showed that the efficiency of the cell is reduced as intensities of sunlight are reduced but at a rate different from the reduction in intensities.
This document summarizes the equations and applications associated with the photovoltaic array performance model developed at Sandia National Laboratories over the last twelve years. Electrical, thermal, and optical characteristics for photovoltaic modules are included in the model, and the model is designed to use hourly solar resource and meteorological data. The versatility and accuracy of the model has been validated for flat-plate modules (all technologies) and for concentrator modules, as well as for large arrays of modules. Applications include system design and sizing, 'translation' of field performance measurements to standard reporting conditions, system performance optimization, and real-time comparison of measured versus expected system performance.
This paper provides new test methods and analytical procedures for characterizing the electrical performance of photovoltaic modules and arrays. The methods use outdoor measurements to provide performance parameters both at standard reporting conditions and for all operating conditions encountered by typical photovoltaic systems. Improvements over previously used test methods are identified, and examples of the successful application of the methodology are provided for crystalline- and amorphous-silicon modules and arrays. This work provides an improved understanding of module and array performance characteristics, and perhaps most importantly, a straight-forward yet rigorous model for predicting array performance at all operating conditions. For the first time, the influences of solar irradiance, operating temperature, solar spectrum, solar angle-of-incidence, and temperature coefficients are all addressed in a practical way that will benefit both designers and users of photovoltaics. {copyright} {ital 1997 American Institute of Physics.}
The Solar Cell Array Design Handbook is written at a practicing engineering level and provides a comprehensive compilation of explanatory notes, design practices, analytical models, solar cell characteristics, and material properties data of interest to personnel engaged in solar cell array performance specification, hardware design, analysis, fabrication and test. Twelve handbook chapters discuss the following: historical developments, the environment and its effects, solar cells, solar cell filters and covers, solar cell and other electrical interconnections, blocking and shunt diodes, substrates and deployment mechanisms, material properties, design synthesis and optimization, design analysis, procurement, production and cost aspects, evaluation and test, orbital performance, and illustrative design examples. A comprehensive index permits rapid locating of desired topics.
A model for the thermal behavior of a flat plate photovoltaic (PV) array is proposed. In the model both radiative heat loss - which is usually ignored - and the electric output of the PV array are considered. It has been shown that the radiative heat loss represents a significant part of the overall heat loss; thus its neglect is shown to result in an overestimated solar cell temperature, and consequently the electric output of a PV array is underestimated. The effect of the PV module's packing factor on the thermal behavior of the modules has been included in the model. A closed form accurate but still simple formula for the solar cell operating temperature (Tc) is given. Good agreement between the experimentally measured values of Tc - obtained at the field - and those predicted by the model has been observed.
The United States Department of Energy has installed four flat-plate intermediate-sized photovoltaic systems to assess the performance of various system designs. The systems have been extensively instrumented; data are collected each minute, averaged over ten minutes, and recorded on magnetic tape. The averages are collected via telephone and archived. The analyses described here were based on averages obtained from four flat-plate systems. The two objectives of the study were (1) to develop equations that could be used to predict future performance and (2) to determine if system degradation were occurring. Equations for power, cell temperature, and dc efficiency were developed using linear regression techniques. The results indicate that system power and cell temperature can be determined as a linear relationship of climatic conditions. However, efficiency cannot be modeled as a linear function.
A simplified algorithm to predict the average steady-state temperature of the solar cells in a photovoltaic array has been developed. The methodology can be applied to arrays on the roof (or walls) of buildings as well as on the ground. It is intended primarily for residential buildings, although it can be used for any type of building, and considers all four-array mounting systems (rack, stand-off, direct, and integral). Input parameters in this development include weather (insolation, ambient temperature, wind speed, humidity, and sky cloud cover), as well as building construction and operation characteristics. The photovoltaic array's geometrical, optical, and thermal properties are used in the analysis as well. Natural or forced convection under the solar panels and/or in the building attic below can also be accounted for by this model. The model has been partially verified against limited measured data and found to be in very good agreement for wind speeds of 1m/s or more.
In this communication, an attempt has been made to develop a thermal model of an integrated photovoltaic and thermal solar (IPVTS) system developed by previous researchers. Based on energy balance of each component of IPVTS system, an analytical expression for the temperature of PV module and the water have been derived. Numerical computations have been carried out for climatic data and design parameters of an experimental IPVTS system. The simulations predict a daily thermal efficiency of around 58%, which is very close to the experimental value (61.3%) obtained by Huang et al.
A method is developed to predict the long-term performance of direct-coupled PV pumping systems. The method uses only information available from the PV module and pump-motor manufacturers. Weather data are “generated” from monthly averages of horizontal radiation and ambient temperatures using well-known weather data statistics. The method predicts monthly pumped water to within 6% of TRNSYS predictions based on hourly weather data. The use of a single monthly-average day is shown to underpredict monthly pumped water at low monthly average radiation levels and overpredict monthly pumped water at intermediate radiation levels. Only at high radiation levels does the use of a single monthly-average day provide a reasonable estimation of monthly pumped water.
This paper describes the modelling of flow rate in a photovoltaic (PV) driven, roof slate based solar system for preheating ventilation air in cold climates. The system consists of a photovoltaic driven, attic mounted fan, which draws air through the spaces between the warm slates and delivers it through a metallic flexible duct into a house. A model for predicting the flow rate of air as a function of irradiance and ambient temperature is developed based on the measured performance of the different components of the system. Considering all experimental sources of error, the model predicts the flow rate of air with a maximum error of 12%. The model is validated for different combinations of components in a roof section constructed at Napier University in Edinburgh. The predicted flow rates are within 10% of the measured values. The model is extended so that it can be applied for different locations and different roof tilts and orientations. A future paper will make use of the model developed herein for system optimisation based on maximum monthly volume of preheated ventilation air delivered. The model will also be used to investigate the effectiveness of PV driven, roof slate based systems as solar air heaters.
The aim of the paper is to derive analytically expressions for the mass flow rate, velocity, temperature rise and location of neutral height (location where the pressure in the air gap is equal to the ambient pressure) in air gaps behind solar cells located on vertical facades. The flow is assumed to be turbulent or laminar and behave as bulk flow, i.e. the velocity and temperature is assumed to be uniform across the air gap and only a function of the height channel. Both the geometry of the air gap and the location of the solar cell module are varied. Aerodynamic end losses are taken into account but only buoyancy-induced flows are considered. The location of the solar cell panel is considered by introducing a configuration factor which is a factor varying between 0 and 1. Redistribution of heat by radiation within the air gap is dealt with. When the aspect ratio is larger than 60 the effect of the location of the solar cell panel is considered by introducing a geometrical configuration factor. The derived expressions for the mass flow rate, velocity and temperature rise are verified against measurements made, using a mock up in the laboratory, where the heat input to the air gap is controlled and the location of the input heat (“solar cell module”) can be varied.
With the rapid increase in Building Integrated Photovoltaic (BIPV) systems and the popularity of photo voltaic (PV) applications, a simple but accurate model to calculate the power output of PV modules is crucial,for evaluating systems. In addition, in the analysis of energy payback, two factors, the power output (maximum power output) model of PV Modules and the representative local weather data, affect calculations of the energy savings and the payback time of BIPV systems. Most studies take the efficiency of PV modules as constant when calculating the energy payback time of PV systems, and ignore the influence of solar radiation and temperature oil the results of the calculation. This study tries to develop one simple, practical, yet more accurate model for describing the characteristics of the power output of PV modules. It develops a model for describing the I-V characteristics of PV modules according to the equivalent circuits of solar cells, by which an accurate but complicated model of the maximum power output (MPO) call be achieved. Taking this MPO model as a benchmark, two other application models from other studies art evaluated and examined. One simplified application model for describing the maximum power output of PV modules is then derived from the results of the simulation. Once the solar radiation on PV panels and the ambient temperature are known, the power output of BIPV systems or PV systems call be calculated accurately and easily.
Predicted performance of a grid connected photovoltaic (PV) system using TRNSYS was compared with measured data. A site specific global-diffuse correlation model was developed and used to calculate the beam and diffuse components of global horizontal insolation. A PV module temperature equation and a correlation relating input and output power of an inverter were developed using measured data and used in TRNSYS to perform PV array and inverter outputs simulation. Different combinations of the tilted surface radiation model, global-diffuse correlation model and PV module temperature equation were used in the simulations. Statistical error analysis was performed to compare the results for each combination. The simulation accuracy was improved by using the new global-diffuse correlation and module temperature equation in the TRNSYS simulation. For an isotropic sky tilted surface radiation model, the average monthly difference between measured and predicted PV output before and after modification of the TRNSYS component were 10.2% and 3.3%, respectively, and, for an anisotropic sky model, 15.4% and 10.7%, respectively. For inverter output, the corresponding errors were 10.4% and 3.3% and 15.8% and 8.6%, respectively. Measured PV efficiency, overall system efficiency, inverter efficiency and performance ratio of the system were compared with the predicted results. The predicted PV performance parameters agreed more closely with the measured parameters in summer than in winter. The difference between predicted performances using an isotropic and an anisotropic sky tilted surface models is between 1% and 2%.
Electrical and thermal simulations of a building integrated photovoltaic system were undertaken with a transient system simulation program using real field input weather data. Predicted results were compared with actual measured data. A site dependent global-diffuse correlation is proposed. The best-tilted surface radiation model for estimating insolation on the inclined surface was selected by statistical tests. To predict the module temperature, a linear correlation equation is developed which relates the temperature difference between module and ambient to insolation. Different combinations of tilted surface radiation model, global-diffuse correlation model and predicted module temperature were used to carry out the simulation and corresponding simulated results compared with the measured data to determine the best combination which gave the least error. Results show that modification of global-diffuse correlation and module temperature prediction improved the overall accuracy of the simulation model. The monthly error between measured and predicted PV output was lied below 16%. Over the period of simulation, the monthly average error between measured and predicted PV output was estimated to be 6.79% whereas, the monthly average error between measured and predicted inverter output was 4.74%.
This book discusses the performance and design of photovoltaic systems involving silicon solar cells (be they single-crystal, polycrystalline, or amorphous). The photovoltaic effect can be produced using other materials, such as gallium arsenide or cadmium sulfide; to date, however, silicon is by far the most common material used in commerically available solar cells. Most of the principles presented here will be transferable to other types of PN junctions.
As photovoltaic systems become larger and more numerous, improved methods are needed for testing and modeling their performance. Test methods that successfully separate the interacting, time-of-day dependent influences of solar irradiance, operating temperature, solar spectrum, and solar angle-of-incidence have now been developed. These test methods have resulted in a new array performance model that is reasonably simple, yet accurately predicts performance for all operating conditions. This paper describes the new model, outdoor tests required to implement it, results of field tests for five arrays of different technologies, and the evolution of the model into a numerical tool for designing and sizing photovoltaic arrays based on annual energy production.
Sandia National Laboratories is actively involved in the development of an accurate photovoltaic (PV) performance model, called PVFORM. A necessary part of this modeling effort is the prediction of the operating cell temperatures. This report describes a computer model that accurately predicts the cell temperature of a photovoltaic array to within 5/sup 0/C. This thermal model requires a minimum amount of input and has been incorporated into PVFORM. The major input parameter to this model is the ''Installed'' Nominal Operating Cell Temperature or INOCT. The program uses INOCT to characterize the thermal properties of the module and its mounting configuration. INOCT can be estimated from the Nominal Operating Cell Temperature (NOCT) and the mounting configuration, or from cell temperature data from a fielded array.
This volume of the series of final reports documenting the FSA Project deals with the Project's activities directed at developing the engineering technology base required to achieve modules that meet the functional, safety and reliability requirements of large-scale terrestrial photovoltaic systems applications. These activities included: (1) development of functional, safety, and reliability requirements for such applications; (2) development of the engineering analytical approaches, test techniques, and design solutions required to meet the requirements; (3) synthesis and procurement of candidate designs for test and evaluation; and (4) performance of extensive testing, evaluation, and failure analysis to define design shortfalls and, thus, areas requiring additional research and development. During the life of the FSA Project, these activities were known by and included a variety of evolving organizational titles: Design and Test, Large-Scale Procurements, Engineering, Engineering Sciences, Operations, Module Performance and Failure Analysis, and at the end of the Project, Reliability and Engineering Sciences. This volume provides both a summary of the approach and technical outcome of these activities and provides a complete Bibliography of the published documentation covering the detailed accomplishments and technologies developed.
The thermal losses to the ambient from a building surface or a roof mounted solar collector represent an important portion of the overall energy balance and depend heavily on the wind induced convection. In an effort to help designers make better use of the available correlations in the literature for the external convection coefficients due to the wind, a critical discussion and a suitable tabulation is presented, on the basis of algebraic form of the coefficients and their dependence upon characteristic length and wind direction, in addition to wind speed. Finally, simple average correlations are produced from the existing ones, useful for quick, gross estimates.
The performance of a roof mounted grid-connected photovoltaic (PV) system in Northern Ireland was monitored over 3 years on annual, seasonal and monthly bases. The overall system performance was adversely affected by low insolation conditions; 19% of total incident insolation was absorbed at irradiance level below 200 W/m2 and 67% below 600 W/m2, only 6·2% above 900 W/m2. In summer and winter, the PV and system efficiencies were 9·0 and 8·5%, and 7·8 and 7·5%, respectively and inverter efficiencies were 86·8 and 85·8%, respectively. The inverter for this particular system was oversized; 77% of the total DC energy produced when inverter's operating load was 50% of its rated capacity. The annual average monthly system performance ratio (PR) was 0·61 with seasonal variation 0·59 to 0·63. The average monthly PV, system and inverter efficiencies over the whole monitored period were 8·8, 7·6 and 86·8%, respectively. The main losses of the system were inverter DC/AC conversion loss, inverter threshold loss and low insolation loss. Copyright © 2007 John Wiley & Sons, Ltd.
The conversion efficiency of photovoltaic modules varies with irradiance and temperature in a predictable fashion, and hence the effective efficiency averaged over a year under field conditions can be reliably assessed. The suggested procedure is to define the efficiency versus irradiance and temperature for a specific module, collect the local irradiance and temperature data, and combine the two mathematically, resulting in effective efficiency. Reasonable approximations simplify the process. The module performance ratio is defined to be the ratio of effective efficiency to that under standard test conditions. Variations of the order of 10% in this factor among manufacturers, primarily the result of the differences in effective series resistance and leakage conductance, are not unusual. A focus on these parameters that control the effective efficiency should provide a path to PV modules with improved field performance. Copyright © 2006 John Wiley & Sons, Ltd.
An empirical relation is derived that allows accurate estimates of the influence of cell temperature variations on the output of a photovoltaic array. Monthly average cell-temperature performance ratios, PRT , can be calculated from the latitude of the site and monthly average values of solar irradiance, air temperature and wind speed. The derivation of the empirical relation for PRT is based on intermediate empirical relations and approximations established by the analysis of a database from stations located at various latitudes and having diverse climatic characteristics. The accuracy of the relation is tested against PRT calculations from short-interval data available in the database. Copyright © 2006 John Wiley & Sons, Ltd.
The thermal characteristics of 11 flat-plate photovoltaic (PV)
modules are investigated and modeled against meteorological elements:
irradiance, angle of incidence, wind speed, plus air and sky
temperatures. Above 500 W/m<sup>2</sup> irradiance, the ratio of the
average difference between module and air temperatures divided by the
incident irradiance is constant, and apparently preordained by module
construction-ranging 27°-40°C/(kW/m<sup>2</sup>) in
value-suggesting that these thermal characteristics are driven by the
incident solar power. When low-irradiance conditions arise under
clear-sky conditions, this ratio becomes small and can exhibit negative
values. In this regime, the module's greater reflectance-resulting from
larger angles of incidence to the sun-coupled with radiant heat emission
dominate the thermal behavior. A new model for the thermal
characteristics is presented that accounts for low- and high-irradiance
regimes and resolves wind-speed dependence
A simplified method has been derived for use in the estimation of the flow rate in naturally ventilated PV cladding for buildings. The method is based on a one-dimensional ‘loop analysis’ in which the buoyancy forces are balanced by the pressure drops due to friction. Wind effects at the entrance and exit are also taken into account. The procedure yields the mass flow rate and temperature rise directly by the solution of a simple cubic equation and therefore is straightforward and simple enough to be put on a spreadsheet. This methodology allows the designer to explore various potential PV configurations at little expense and hence to focus on those designs which warrant further detailed analysis, perhaps coupled to a full building simulation package. In this paper, the fundamental theory behind the loop analysis is described. The hypothesis tested is that the form and values for the friction factors and internal heat transfer coefficients for the buoyancy driven case are the same as those for forced convection in ducts. Next, the experimental rig is discussed with which the first validation exercises are carried out for the no-wind case, using an emulation of the simple single stack PV cladding arrangement. The two key parameters are identified using the measurement error weighted least squares linear regression. Overall excellent agreement between the modelled and measured mass flow rates is seen; the hypothesis is therefore valid. A general model is then derived to describe the thermal behaviour of building-integrated PV with natural ventilation cooling for use in a wide variety of design and validation exercises.
This paper presents a dynamic thermal model based on TRNSYS, for a building with an integrated ventilated PV façade/solar air collector system. The building model developed has been validated against experimental data from a 6.5 m high PV façade on the Mataro Library near Barcelona. Preheating of the ventilation air within the façade is through incident solar radiation heating of the PV elements and subsequent heat transmission to the air within the ventilation gap. The warmed air can be used for building heating in winter. Modelled and measured air temperatures are found to be in good agreement. The heating and cooling loads for the building with and without such a ventilated façade have been calculated and the impact of climatic variations on the performance such buildings has also been investigated. It was found that the cooling loads are marginally higher with the PV façade for all locations considered, whereas the impact of the façade on the heating load depends critically on location.
In this paper, a thermal model of an integrated photovoltaic and thermal solar (IPVTS) water/air heating system has been developed. An analytical expression for the temperature of solar cell and water and an overall thermal efficiency of IPVTS system have been derived as a function of climatic and design parameters. Numerical computations have been carried out for composite climate of New Delhi for parametric studies. Four configurations, namely (a) unglazed with tedlar (UGT), (b) glazed with tedlar (GT), (c) unglazed without tedlar (UGWT) and (d) glazed without tedlar (GWT) have been considered. Comparison of the IPVTS system with water and air heater has also been carried out. It is found that the characteristic daily efficiency of IPVTS system with water is higher than with air for all configurations except GWT. It is also observed that an overall thermal efficiency of IPVTS system for summer and winter conditions is about 65% and 77%, respectively.