Characterizing the Solar Irradiation by Means of Spectral Measurements for Modeling CPV Production

In many places of Southern Europe, the direct normal irradiation exceeds 2000 kWh/(m2a), which makes concentrator photovoltaic (CPV) power plants cost-effective. This kind of solar power plants has a great potential for efficiency increase on respect to single-junction flat-plate PV systems. Since CPV exploits only direct irradiation, and its energy production depends on the shape of the solar spectrum, reliable information on direct irradiation on both the whole solar band and sub-bands where CPV cells junctions work, is mandatory. In this work a direct normal spectral irradiation forecasting method, under clear sky conditions, is presented. This method uses data from numerical weather prediction models that provide aerosol, ozone and precipitable water contents. The forecasts have been validated against observations provided by a pyrheliometer and a solar spectral irradiance meter located in Milan. The analysis has allowed deepening the mechanisms that drive the yield of CPV power plants.