Mapping the Performance of PV Modules: the Influence of Irradiance, Temperature, Wind and Spectral Variations

We present calculations for PV energy yield over continental-scale regions. The calculations take into account the effects of reflectance at shallow angles of incidence, the influence of low irradiance and module temperature on module power output, and the influence of air temperature and wind speed on module temperature. The study has been made for a region comprising Eurasia and Africa, excluding arctic areas. Results show that for crystalline silicon the effects of angle-of-incidence are rather modest, at 2-4% loss of output, while temperature and irradiance effects may range from -20% to +5% depending on location. Considering the cooling effect of wind may change the expected yearly energy output by up to +6-7% in windy desert areas while in other areas the effect is minimal. Recent work on calculating spectrally resolved irradiance from satellite has made it possible for the first time to estimate the effect of spectral variations on PV performance. Preliminary results show that in cloudy tropical areas this could mean up to 6% higher energy output for CdTe modules while the effect would be very small in desert regions.JRC.F.7-Renewables and Energy Efficienc