Revised Performance Data of Small Grid Connected PV Systems Based on in situ Measurements

The mean annual yield (700 kWh/a*kWp) and performance ratio (65%) of small grid connected PV systems which were installed within the 1000-Roofs-Programme in Germany are lower than expected. By investigating the parameters determining the performance ratio it could be shown that for well designed PV systems the PR should range within 70 to 80 %. The real power of the PV arrays as the most critical parameter of the performance ratio was measured with a newly developed PV system analyzer. In most investigated systems the measured power was 10 to 20 % lower than the nominal power. The revised performance data based on the measurements agree with the above given values. Based on a typical irradiation of 1100 kWh/m2 in module plane a mean annual yield of more than 800 kWh/a*kWp can be expected.