Jens,
It won't be cheap to get to 11kw but Outback allows for stacking up to, I think 10 units. They can be stacked in series or parallel; including options for 208volt 3 phase. Check out their webpage;
www.outbackpower.com, lots of information; including distributors (theres one in Victoria).
My friend whom I ordered engines with has a wind generator and an Outback grid-tie inverter. He had some installation issues and more than a few questions- Outback was very helpfull.
Just a thought; when I built my house I set up two breaker panels, one for everyday lower power consumption requirements (lights, fridge, entertainment, bedroom a/c, etc) and one for big draws like split A/C, washer/dryer, tools etc. Right now the Outback runs the everyday side and Island power runs the other and charges the batteries. Once the listeroid is up and running I'll run it to charge batteries and when theres a need for the big a/c, wash clothes, or more demanding tools.
Hope to build a wind generator to take over most of the battery charging by years end.
Good Luck,
Cheers, Fred