Megawatt PV plants in Germany: A south-north performance comparison

Purpose
Stimulated by the German Feed-in-Law, a large number of grid-connected Megawatt PV plants have been put into operation during the last 5 years. Because of the higher irradiance these plants were originally concentrated in the southern part of Germany (Bavaria and Baden-Wuerttemberg). Starting in 2004 some plants have been also installed in other regions of Germany. The paper describes design and operation results of nine plants operating in different regions.

Locations and design
The plant locations are distributed between 47 and 52 degrees northern latitude (Fig.1), covering Germany from South to North. Some technical features of the investigated plants are given in the table below.

The most plants were built on heavily used or loaded areas (former industrial sites or waste sites). Different types of fundaments and rack support constructions (desks) were used for the module mounting (Fig.2.). The connection with the grid was done in the 10 to 20 kV voltage level, the distance between the plants and the grid was several thousands meters in some cases. The most plants started their operation before 2006. The operation of the plants is monitored by the owners or by professional service providers.

Results and conclusions
The operation results of the year 2007 are exemplarily presented. The solar irradiance in 2007 was higher than the long year average, similar to the years before. The final yield of the plants ranges between 940 and 1180 kWh/kW (Fig. 3). The final yield of the tracked plant in Borna surpasses the yield of the other plants by 25%.
The performance ratios were determined to be between 0.75 and 0.92 (Fig. 4). In the most cases the PR values surprisingly ranges between 0,82 and 0.86. The sources of energy losses are analysed and discussed. Finally a long term estimation of the yield for the different plants will be given.