The performance of photovoltaic (PV) modules in outdoor field conditions is adversely affected by the rise in module operating temperature. Wind flow around the module affects its temperature significantly, which ultimately influences the module output power. In this paper, a new approach has been presented, for module temperature estimation of different technology PV modules (amorphous Si, hetero-junction with intrinsic thin-layer (HIT) and multicrystalline Si) installed at the site of National Institute of Solar Energy (NISE), India. The model based on presented approach incorporates the effect of wind speed along with wind direction, while considering in-plane irradiance, ambient temperature, and the module efficiency parameters. For all the technology modules, results have been analyzed qualitatively and quantitatively under different wind situations. Qualitative analysis based on the trend of module temperature variation under different wind speed and wind direction along with irradiance and ambient temperature has been presented in detail from experimental data. Quantitative results obtained from presented model showed good agreement with the experimentally measured data for different technology modules. The model based on presented approach showed marked improvement in results with high consistency, in comparison with other models analyzed for different technology modules installed at the site. The improvement was very significant in case of multicrystalline Si technology modules, which is most commonly used and highly temperature sensitive technology. Presented work can be used for estimating the effect of wind on different technology PV modules and for prediction of module temperature, which affects the performance and reliability of PV modules.

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The accuracy of outdoor performance of a photovoltaic (PV) array can be improved by considering the spectral effects. In this paper, the impact of seasonal spectral variations on the three different silicon PV technologies: single junction amorphous silicon (a-Si), Heterojunction with Intrinsic Thin-layer (HIT) and multi crystalline silicon (mc-Si) has been presented first time in Indian environmental conditions. The spectral effect on HIT PV module technology has been presented first time along with the first simultaneous study of variation in spectral indicators by useful fraction (UF), average photon energy (APE) and spectral mismatch factor (MMF), based on monthly and seasonal data. The maximum observed variation in UF was 26.4, 8.2, 10.8 %, while in MMF, variation was up to 24.7, 7.6, 8.2 % for a-Si, HIT and mcSi, respectively, and in APE variation was up to 15.3 %. Among all three technology modules, first time reported HIT technology showed the least variation while maximum variation was observed in a-Si technology. The observed spectral effect variations have been discussed on Performance Ratio and compared with reported results of other global sites. The value and trends of spectral parameters are important to understand the effect of spectral variation on different technology. This study is especially important in Indian subcontinent perspective because of the strong monsoon season, where observed variation in the spectrum-related parameter found to be highest among all the seasons.

India is implementing one of the world's largest solar PV program. For better performance assessment of large PV installations, module temperature plays an important role. Estimation of power generation in hot climatic countries like India can be improved by the use of appropriate module temperature correlation. The accuracy of module temperature correlations has been observed to be related with climatic conditions. In this work, different explicit and implicit correlations have been evaluated in different temperature ranges based on frequency of occurrence of three very different technology PV modules: amorphous silicon, hetero‐junction intrinsic thin layer, and multicrystalline silicon at Indian site. Results show that Faiman correlation is most efficacious for all technology PV modules under highest frequency of occurrence temperature range. It has been observed that accuracy of correlations decreases from low module temperature range toward high module temperature range for all technology PV modules, except in case of Faiman correlation. In case of multicrystalline silicon, which is most widely used technology, the variation in accuracy of correlations was highest. This frequency of occurrence‐based comparison of correlation's accuracy is efficient and beneficial for better performance assessment of PV systems, especially in Indian context due to its large solar mission.

Photovoltaic (PV) module performance varies under actual outdoor environmental conditions, which can be better analyzed by relating performance with the frequency of different operating conditions. In this paper, the frequency of occurrence under the IEC 61853-1 standard has been exploited for proposing the concept of the frequency distribution of operating conditions for photovoltaic modules and analyzed for amorphous silicon, heterojunction with intrinsic thin-layer, and multi-crystalline silicon PV technology modules simultaneously, from the measured data of 2 years at the site of the National Institute of Solar Energy, India. A relative comparison has been presented between different technology modules, and the most frequent operating condition (MFOC) has been obtained from the proposed frequency distribution under the IEC 61853-1 standard. The results show that MFOC and the maximum energy contribution of all technology modules co-existed under the same IEC 61853-1 condition centered at an irradiance of 800 W/m2 and a module temperature of 50 °C, which could be advantageous while formulating an alternate standard for better performance assessment as compared to the standard test condition (STC). The power deviation from STC under MFOC was estimated in the range of 23%–37% for different technology modules, which can lead to a significant impact in performance estimation. While considering the significance of MFOC, a model applicable to modules of variable sizes has been presented for future power prediction under MFOC. The results of the presented model showed good agreement with experimental results for all the technology modules. This work can be helpful for planners, installers, financers, and consumers for better estimation of PV performance.