Two year performance evaluation of different grid connected photovoltaic systems

The performance and energy produced by photovoltaic (PV) systems installed at any location depends to a great extent on the environmental conditions they are exposed to and their technology. This paper presents the two year evaluation of thirteen (13) different types of PV systems which have been evaluated under real conditions in Nicosia, Cyprus and Stuttgart, Germany. The fixed flat plate systems under test have shown an average annual energy yield (ac) of 1580 kWh/kW_p with a solar irradiation at the plane of array (POA) of 1997 kWh/m² for the first year of operation in Nicosia, whereas in Stuttgart the respective average energy yield (ac) was recorded to be 1194 kWh/kW_p and the solar irradiation at the POA was 1460 kWh/m². During the second year of operation, the fixed mounted average energy yield (ac) was 1609 kWh/kW_p (+1.8%) and 1066 kWh/kW_p (-10.7%) for the systems in Nicosia and Stuttgart respectively. The solar irradiation at the POA in Nicosia was 2050 kWh/m², an increase of 2.6% from the first year and in Stuttgart, 1306 kWh/m² showing a decrease of 10.5%. Accordingly the performance ratio (PR) on the ac side for the systems in Nicosia, was between 73% - 85% in the first year whereas in the second year between 70% - 84%. In Stuttgart the systems have shown higher ac PR than in Nicosia, in the range of 76.2% - 88.5% in the first year and 72.3% - 88.5% in the second year of operation.