Operational Experiences with Megawatt PV Plants in Central Germany

Purpose
Stimulated by the German Feed-in-Law, a 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 Central Germany. The paper describes design and operation results of seven plants operating in the region of Saxony and Thuringia.

Locations and design
The most plants are concentrated in a region earlier defined by the DWD as "solar island" around Leipzig and Chemnitz. One plant is located in north-west Thuringia.
All 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. 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. All 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 2006 are exemplarily presented. The solar irradiance in 2006 was higher than the long year average, similar to the years before. The final yield of the plants ranges between 950 and 1050 kWh/kW. These surprisingly high values are near the values which were only found in Germany south of 50° latitude so far. 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 0.77 and 0.84. The sources of energy losses are analysed and discussed. Beside component failures in the plants also grid disconnections reduced the feed-in energy in some cases.
Finally a long term estimation of the yield for the different plants will be given. Based on the data of the year 2006 a mean yield between 900 and 1000 kWh/kW can be expected.