Many PV systems exhibit a poorer performance as is to be expected using installed peak power. Performance ratios of ＇reasonable＇ systems have experimentally been determined in the range of 60%-85% of STC (=standard test conditions) performance. A significant pan of the losses is due to the performance deviation of PV modules from their rating at STC due to the outdoor conditions (realistic reporting conditions, RRC). This is due to law light level dependence, temperature coefficients, nominal operating cell temperatures and reflectivity at the module surface. Due to the special operating conditions, this is of special importance if PV modules are integrated into buildings. To overcome the problems in module performance evaluation and to assist system sizing, a realistic PV efficiency map and performance data for commercial PV modules are presented. In a similar way as the European radiation atlas for solar irradiation, this RRC market survey of PV modules gives detailed information on module performance at many sites for various installation conditions. As the International Electrotechnical Commission is currently preparing a new international standard, dealing with the safety of PV modules in a variety of application classes, performance data on PV modules is supplemented by information on possible module safety tests and module integration into buildings.