Operating Temperature Of Photovoltaic Module Research Articles

Al2O3/graphene/PVDF‐HFP radiative cooling coating reinforced heat dissipation of BIPV modules

AbstractBuilding integrated photovoltaic modules, applied to industrial and commercial buildings, generally used metal as the backsheet. In summer, the operating temperature of modules is as high as 70°C, resulting in instability of output power and service life. Therefore, it is very important to reduce the operating temperature of photovoltaic modules. In this work, Al2O3/graphene/poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) composite radiative cooling coatings were prepared and utilized for reinforcing heat dissipation of photovoltaic modules. The results indicate that 0.75 wt%Al2O3/1wt%graphene/PVDF‐HFP composite coating exhibited a thermal diffusivity of 3.24 μm2/s and an average emissivity of 0.94. The maximum temperature drop of the coating in the outer door reached 5.8°C. In addition, a mini photovoltaic module coated with the composite coating achieved the cooling effect of 2.4°C, and the output power and conversion efficiency were increased by 5.8% and 7%, respectively. This demonstrates that the heat conduction radiative cooling coating possesses potential applications for improving the reliability of photovoltaic modules.

Multilayered PCMs-based cooling solution for photovoltaic modules: Modelling and experimental study

The higher operational temperature during the Indian summer reduces the power conversion efficiency (PCE) of Silicon-based photovoltaic (PV) modules and also shortens their lifetime. Recently, phase change materials (PCMs) have been used as a passive cooling technique that can bring down the temperature of PV modules. In this study, we investigated the multilayered PCM system that can render thermal management in all seasons, owing to the combination of low and high melting point PCMs. The previous studies conducted on these multilayered PCMs have only performed simulations to evaluate these systems, and to the best of our knowledge, systematic experiments have not been performed to establish the merit of multi-layer PCM arrangement. Experiments on multilayered PCM showed a lower maximum temperature of PV module by 4 °C and 7.2 °C when compared to single-layer PCM and PV reference respectively. Theoretical calculations indicate that using the multilayered PCM system can successfully regulate the operating temperature of PV modules in all seasons with 3.3% higher yearly electric output, extend PV life by almost ten years and nearly double the lifetime earnings. Therefore, this work lays the groundwork for the commercialization of thermal management systems for PV modules using the multilayered PCM approach.

Outdoor Thermal Performance of Photovoltaic Devices with Enhanced Daytime Radiative Cooling Glass

The increase in the operating temperature decreases the efficiency and the lifetime of photovoltaic (PV) systems. Radiative cooling effect offers a promising solution to passively reduce the operating temperature of PV modules using the atmospheric window (AW). Glass is a well‐known material used as front cover of PV modules. It presents a fairly good emissivity in the AW although a low‐absorption resonance at 9–10 μm decreases its overall emissivity, hampering its radiative cooling capacity. This effect can be reduced by tailoring the glass surface. Herein, glass samples are microstructured and characterized obtaining a decrease in reflectance and a substantial increase of the emissivity in the AW. Next, the glass samples are laminated with solar cells and installed outdoors without any convection barrier and monitored in open‐circuit configuration for almost half a year. The days are sorted by three meteorological conditions: sunny, partly cloudy, and cloudy days, which correspond to a decreasing availability of the AW. The average temperature difference between two samples is 0.8, 0.7, and 0.1 °C for the sunny, partly cloudy, and cloudy days, respectively. The maximum temperature difference obtained is 2.0 °C. No correlation between temperature difference and wind speed is observed.

Concepts for heat utilization and passive cooling techniques to improve reliability and performance of Building Integrated Photovoltaics (BIPV)

When integrated into urban environments, photovoltaic (PV) systems usually present operational temperatures that are significantly higher than those shown by rack-mounted systems. High operating temperatures are associated with reduced reliability of PV modules and significantly impact the electrical performance of solar cells. Utilizing the heat produced on PV modules or reducing operating temperatures can bolster their application within the building sector. We present the three main concepts studied to achieve these goals. First, a PV is a chimney concept that allows the use of the heat generated by the modules. Simulations for a PV chimney installed on a building in the Netherlands showed that although the heat quality produced inside its cavity was low, the potential use of the air mass flow for ventilation applications is promising. Additionally, we present two passive cooling solutions that can reduce the operating temperatures of PV modules: Optical filters and phase change materials. Experimental measurements in Delft showed that these solutions reduce the operating temperature of PV modules between 4 °C to 20 °C, particularly under high irradiance hours.

Investigating the Effect of Radiative Cooling on the Operating Temperature of Photovoltaic Modules

Due to the linear decrease in power conversion efficiency with temperature, effective methods for the thermal management of silicon photovoltaics (PV) are urgently needed. Recently, the emergence of radiative cooling technologies has breathed new life into this topic. Some previous studies claimed the value of an additional radiative cooling coating on silicon solar cells, whereas quantitative analysis based on comprehensive experiments and modeling is still not available in literature to give an explicit conclusion. After developing the coupling electrical–thermal model for simulating various cases and conducting field experimental tests, herein, it is aimed to clarify the effect of radiative cooling on the temperature of normally installed PV modules and influence of factors such as thermal convection and thermal emissivity. Results show that the increased thermal emissivity results in only an average temperature drop of less than 1.0 °C, whereas the ventilation conditions have an impact of over 10 °C. The simulation study also demonstrates that a limit of around 2.0 °C in temperature reduction is all the value of an additional radiative cooling coating on PV modules. To make an additional radiative cooling coating on existing PV panels cost effective, the work suggests developing multifunctional coatings in the future.

Thermodynamics assessment on cooling photovoltaic modules by phase change materials (PCMs) in critical operating temperature

Increasing the temperature of photovoltaic (PV) cells decreases their electricity generation. The use of phase change materials (PCMs) is one of the most common methods for controlling the rate of increasing the temperature of PV cells. This research focuses on thermodynamic analysis of PV/PCM systems with and without fins in maximum operating temperature of PV modules (85 °C). Polyethylene glycol 600 (PEG-600) and paraffin, with different melting points, have been studied experimentally as PCM in an indoor condition. Moreover, the effect of using fins was investigated. For this critical temperature, the results showed that using paraffin could be better for controlling the temperature of PV cells, due to its closer melting point with the module temperature. In the case of fins included, the temperature differences of 28.0 °C and 8.8 °C between the case of paraffin + fin and the case of PEG 600 + fin in comparison with the conventional PV module were measured, respectively. At this critical temperature condition, the output power of a PV module cannot exceed the half of its nominal power. The exergy efficiency of the paraffin + fin case was measured to 4.2% more than the conventional one. Also, entropy generation was calculated and reduction up to 5% was shown for paraffin + fin in comparison with the conventional one. Moreover, variations of the Rayleigh number for proposed cases are calculated too.

An Experimental Study on Cooling the Photovoltaic Modules by Fins to Improve Power Generation: Economic Assessment

Photovoltaic (PV) power plant is one of the most important renewable power generation methods, which is rapidly developing. One of the weak points of PV power plants is the negative effects of increasing the cells temperature on their power generation. In this study, a simple and low cost method is proposed to reduce the temperature of these panels. The use of fins has been proven in many industrial applications and here it is used as coolant of PV panel. This experiment was performed in maximum operating temperature of photovoltaic modules which is known as 85°C. By using numbers of aluminum fins on the back surface of photovoltaic panels under two different irradiation, the temperature reduction up to 7.4 °C was observed, and this reduction leads to 2.72 % increasing in efficiency. Finally, an economical assessment of the offered cases based on output power of PV panels carried out, which shows a suitable economic justifiability.

Temperature measurement of solar module in outdoor operating conditions using thermal imaging

In this paper, a method to determine the operating temperature of photovoltaic module in outdoor conditions using thermal imaging is presented. Importance of temperature in PV module performance is well known at design and monitoring level. As manufacturer provide module specifications at STC (25 °C, 1 KW/m2) and the outdoor conditions are different, so in order to know the change in actual output of PV module and to track maximum power point with temperature in real time, it is important to determine the exact temperature of PV module in outdoor operating conditions. Existing techniques to determine the OOT have many drawbacks as discussed in paper. To overcome those drawbacks, a non-invasive and more accurate technique is suggested to measure module temperature in operating conditions. An experimental setup was established in outdoor and infrared images of PV module were captured using a Flir Infrared camera. These images were further processed quantitatively to calculate the temperature of module. To validate the results, actual field output data was compared to values calculated with the help of well-established relations available in literature at different temperatures calculated using existing techniques. Parameters calculated using thermal imaging method were most nearer to the actual field output data.

Estimation of the operating temperature of photovoltaic modules using artificial intelligence techniques and global sensitivity analysis: A comparative approach

In this work, four artificial intelligence (AI) techniques, based on Artificial Neural Networks, Support Vector Machine (SVM), and Regression Tree Ensembles, were used to estimate the operating temperature of photovoltaic (PV) modules (TPV). The models' input parameters correspond to experimental measurements of environmental (solar radiation, ambient temperature, relative humidity, wind speed, and wind direction) and operational (power output and tracking system) variables. Several AI models were trained and statistically compared with the measured data using a computational methodology that determines the performance and accuracy of the AI technique. Finally, a global sensitivity analysis was conducted to identify the ability of each technique to reflect the physical coherence of the phenomenon that is under study. It is reported that the four techniques can provide an estimate having a precision of about 93%. On the other hand, the sensitivity analysis demonstrates that all the models cannot correctly interpret the physical interaction of the input parameters with respect to TPV, where the SVM is reported to be the most appropriate. The results indicate that the proposed methodology is a viable alternative for the estimation of TPV by AI techniques. This methodology can be implemented as an alternative tool in the development of smart PV module cooling systems to improve its performance and to reduce its operating costs.

Implementation of Maximum Power Point Tracking (MPPT) Technique on Solar Tracking System Based on Adaptive Neuro-Fuzzy Inference System (ANFIS)

Characteristic I-V of photovoltaic is depended on solar irradiation and operating temperature. Solar irradiation particularly affects the output current where the increasing solar irradiation will tend to increase the output current. Meanwhile, the operating temperature of photovoltaic module affects the output voltage where increasing temperature will reduce the output voltage. There is a point on the I-V curve where photovoltaic modules produce maximum possible output power that is called Maximum Power Point (MPP). A technique to track MPP on the I-V curve is known as Maximum Power Point Tracking (MPPT). In this study, the MPPT has been successfully designed based on Adaptive Neuro-Fuzzy Inference System (ANFIS) and integrated with solar tracking system to improve the conversion efficiency of photovoltaic modules. The designed ANFIS MPPT system consists of current and voltage sensors, buck-boost converter, and Arduino MEGA 2560 microcontroller as a controller. Varying amounts of lamp with 12V 10W rating arranged in series is used as load. Solar tracking system that is equipped with MPPT ANFIS able to increase the output power of photovoltaic modules by 46.198% relative to the fixed system when 3 lamps is used as load.

Operating Temperature of Photovoltaic Module for Retrofitted Grid-Connected Photovoltaic System on Metal Roof

Operating Temperature of Photovoltaic Module for Retrofitted Grid-Connected Photovoltaic System on Metal Roof

Models to predict the operating temperature of different photovoltaic modules in outdoor conditions

AbstractThe operating temperature of photovoltaic modules under real operating conditions is important information when designing and sizing those systems. This paper proposes new models to predict this temperature for different technology modules under the climate conditions of southern Spain using meteorological parameters. The proposed models are hourly and instantaneous. Those models are compared with previous models existing in the literature. The results obtained show that because of the thermal inertia of the modules, only the proposed hourly models allow the average temperature of the modules to be determined accurately. The temperature of the modules can be predicted using the two‐parameter hourly model proposed in this paper with a mean absolute percentage error less than 6.0% for the technologies tested. Copyright © 2014 John Wiley & Sons, Ltd.

Operating temperature of photovoltaic modules: A survey of pertinent correlations

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.

Assessing the outdoor operating temperature of photovoltaic modules

AbstractBy a careful study of data collected from seven varieties of photovoltaic (PV) module it is demonstrated that a simple modified form of the Hottel–Whillier–Bliss (HWB) equation, familiar from the analysis of flat‐plate solar–thermal collectors, can be employed to predict module temperatures within an accuracy comparable to the cell‐to‐cell temperature differences typically encountered within a module. Furthermore, for modules within the range of construction parameters employed in this study, the actual values of the two modified HWB constants do not appear to depend upon module type. The implication of these results for the accuracy of outdoor module characterization is discussed. Copyright © 2008 John Wiley & Sons, Ltd.