Intercomparison of Different Energy Prediction Methods Within the European Project "Performance" - Results of the 1st Round Robin

Eight separate energy prediction methods, developed independently across European Universities and Research Centres, have been compared with respect to their estimated DC energy generation for five different photovoltaic (PV) module technologies and 7 different sites distributed over whole Europe. The analysis of this work is the basis for further improvements of each of the modelling approaches and thus enables a reduction of the prediction error in PV yield estimations. The recently completed first of three planned round-robin inter-comparisons found that the agreement for all methods and all technologies is within ±5% on an annual basis, provided that the environmental parameters incident irradiance and the module temperature are well described. This good accuracy was also found when translating the energy yield measured at one location in Europe to another for an identical module utilising shorter time periods (months). Significantly higher errors were found when using different PV modules of the same manufacturer and technology to predict the energy yield at other sites. Here the variation in module power rating dominated the results of the energy prediction methods and a correction for these differences had to be applied