The Fraunhofer Institute measures the systems while they are running, the results are analysed and evaluated. Within 24 hours, the monitoring process highlights not just deviations from the forecast yield values of the system, but also the causes of errors, such as problems with the inverter or shading.

The evaluation routine developed by the Fraunhofer ISE delivers the solar irradiance, yield and the performance ratio of each system daily. The data is updated daily and shown in an easy-to-read way for each installation. Through performance controlling it can be ascertained whether the forecast yields of the system are being met. Very good PV systems reach a performance ratio of over 80 %.