I've ben thinking about your problem when your voltage increases on windy days. Most electrical equipment used to be designed to be able to handle a 10% voltage swing. Most of the stuff manufactured today is built to sustain a 5% swing in voltage. This is done to keep costs down.

Most inverters act as voltage regulators on the conversion from DC to AC voltage. I'd be concerned with the voltage swing you are showing and have the inverter looked at to make sure it is still operating correctly. Jim

Thanks hullguy fo your thoughts. The electronics of the windmill system are probablhy at fault. Your thoughts about age related to circuitry 5% v. 10% is probably valid. Ours is an older system which we bought used, though the electronics portion had to be replaced at our home several yrs ago.

Love the way you have your house hooked up to alternative energy. Someday I hope to have the resources to be able to set up a wind turbine in my backyard!!!

My union Local 103 in Boston is a big proponent of wind energy. Here's a link to the wind turbine we have set up in front of our hall.
http://www.ibew103.com/node/605

Hullguy:
I looked at the pics. What is the sweep (diameter) of the blades. How high is the tower. Looks like it might be muti-hundred kw and megawatt turbine.

Recently there were 28 wind turbines set up on a mountain 15 miles south of our home. The generators atop the towers are said to weight 55 tons. There are two blades; each is much greater than 75'. Perhaps 100'.

So lots of power will be produced, but we're told that the energy will go South and that our energy costs will not be reduced due to green power up here. Not surprised!!

So I guess the moral of the story is that if you want to reduce your energy costs you have to do it yourslef.