Geographical Variation of the Conversion Efficiency of Crystalline Silicon Photovoltaic Modules in Europe

Me present a geographical assessment of the performance of crystalline silicon photovoltaic (PV) modules over Europe. We have developed a method that is based on a material specific analytical expression of the PV conversion efficiency, relative to nominal efficiency, as a function of module temperature and irradiance. This method is combined with a climate database that includes average daytime temperature and irradiance profiles. It is found that the geographical variation in ambient temperature and yearly irradiation causes a decrease in overall yearly PV performance from 3 to 13% relative to the performance under Standard Test Conditions, with the highest decrease found in the Mediterranean region. Based on the above results we developed a simplified linear expression of the relative PV module efficiency that is a simple function of yearly total irradiation and yearly average daytime temperature. The coefficients to the linear expression are found by fitting to the map resulting from the above-mentioned analytical approach. The prediction of total yearly PV output from this linear fit deviates less than 0.5% from the more detailed calculation, thus providing a faster and more simplified alternative to the yield estimate, in the case when only limited climate data are available. Copyright (C) 2008 John Wiley & Sons, Ltd.