Yes, the wind has definitely dropped over the last 2 years - which is why we have had such cold and snowy winters! The jet stream which normally provides us with relatively warm westerly winds - (good for our wind turbines) - has moved to drag in cold northerly winds. This with high pressure sytems, has seen a marked reduction in the output of our Proven 6kW Turbine.
Our first year (Jul 07 to Jul 08) produced 17.25mWh's; 08 to 09 15.25mWh's. This calendar year - 2010 produced only 10.2mWh's.

We have had similar problems to yourself. First a yaw bearing bolt sheared; this did not cause too much of a problem, and I just replaced the bolt. I contacted Proven, and they said the blades maybe out of balance, and sent me a new set! These were supposed to be more efficient, which may have lead to the same problem you had - DC overvoltage. The Windy Boy can cope with up to 500vdc, by dragging down the amperage to limit output to 6kW. However in these strong winds, you often get blips in the grid supply (lights flickering). The Windy Boy senses this as a grid failure (0.2 of a second) and disconnects from the grid. This sends the dc voltage way above the 500v - (turbine unloaded). The Windy Boy will now not reconnect to the grid till the wind drops - which can be several hours. Proven's solution was a modified Control Box (rectifier) and 3 x 1kW heaters (1 for each phase) to load up the turbine to help reduce the dc voltage. A relay closes at about 450v and the heaters come on. Output can now be up to 9kW's.

Our Windy Boy failed during a bad storm, with "K1 relay open". We had a new one fitted, and like yours, supposedly more efficient...

Interesting about the blade springs. I do my own servicing and our springs appear ok, just the spacers wearing; but I will check more carefully this next annual service. If you look at pictures of the new Proven 11 (6kw!!) it has what looks like just 3 hydraulic rams instead of 3 sets of springs...

Finally, today, have just past 50mWh's

Peter Benning