In it's location the solar is very effective, the 4kw is the actual generation rather than a label rating. 100% full sun, no shade, no clouds. The array typically generates over 20kw per day. The house is pretty efficient and the weather is very nice both summer and winter. This is not an area with a harsh winter or summer.
Shade and clouds of any kind, even very minor, have a HUGE effect on the production of a solar array.
Absolutely. Clouds also have a profound effect on solar output, I think much more than people realize. I am not english but my understanding is that london has a lot of clouds.
Shade and clouds of any kind, even very minor, have a HUGE effect on the production of a solar array.