A method for the prediction of Energy Production (EP) in Concentrating
Photovoltaic (CPV) installations is examined in this study. It presents a new method that
predicts EP by using Global Horizontal Irradiation (GHI) and the Photovoltaic
Geographical Information System (PVGIS) database, instead of Direct Normal Irradiation
(DNI) data, which are rarely recorded at most locations. EP at four Spanish CPV
installations is analyzed: two are based on silicon solar cells and the other two on
multi-junction III-V solar cells. The real EP is compared with the predicted EP. Two
methods for EP prediction are presented. In the first preliminary method, a monthly
Performance Ratio (PR) is used as an arbitrary constant value (75%) and an estimation of
the DNI. The DNI estimation is obtained from GHI measurements and the PVGIS
database. In the second method, a lineal model is proposed for the first time in this paper to
obtain the predicted EP from the estimated DNI. This lineal model is the regression line
that correlates the real monthly EP and the estimated DNI in 2009. This new method
implies that the monthly PR is variable. Using the new method, the difference between the
predicted and the real EP values is less than 2% for the annual EP and is in the range of
5.6%–16.1% for the monthly EP. The method that uses the variable monthly PR allows the
prediction of the EP with reasonable accuracy. It is therefore possible to predict the CPV
EP for any location, using only widely available GHI data and the PVGIS database.
