Photovoltaic Power Systems Programme (IEA - PVPS Task 2), report IEA-PVPS T2-07:2008This document reports, in the first part, on the possibility to use solar irradiation calculated from satellite images for performance predictions. In the second part, different system performance evaluation models are described. The use of calculated irradiations as an input to a simple parametric model is compared with measurements from systems existing in the Task 2 Performance Database. Conclusions are drawn on the related achievable accuracy