Speaking of the dangers of unwary investment in young technologies by private individuals, he warned against purchasing products directly from the drawing board. A new DGW publication lists over 100 turbines from 38 manufacturers which are currently offered on the German market. But only 17 of these fulfil the criteria developed by DGW for a safe buy.
Listing these criteria, Carstensen said each wind turbine should be sold with: a German type approval certificate; with power curve and noise emission measurements by a recognised institute; with a confirmation of compatibility with the grid from a German electric utility; with a documented minimum number of installed and tested turbines (preferably five); with a guaranteed technical availability of 95% and guaranteed power output curve to be included in the purchase contract; and with a minimum period of operation of the prototype of one year.
According to DGW, the wind turbine types so far fulfilling all these criteria are produced by AN Bonus (150 kW and 450 kW), Enercon (500 kW), Micon (225 kW and 400 kW), Nordtank (150 kW, 300 kW and 500 kW), Tacke (80 kW, 500 kW and 600 kW), Vestas (500 kW) and Wind Technik Nord (200 kW).