This photo from southern Germany Aug '09 has a house in the background with?... well I counted 28, but if there is no dormer at the far end, it could be as many as 32 - nearly 6kW! If the sun is strong enough to need to shade the eyes, it's gotta be good for power generation. It demonstrates the benefits of building houses with south-facing 40º roofs! See German Energy Agency.
If you want to know more about the young lady in the photo, she is currently riding a tandem bike from Norwich to Istanbul, which you can read about in her cycling blog.