[duffpkg]

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.

[pyrale]

London's latitude is north of Calgary.

I don't know how far south you are, but 15-20° of latitude has a significant impact on the effectiveness of solar, especially during winter.

[duffpkg]

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.

[insane_dreamer]

> 100% full sun, no shade, no clouds ... the weather is very nice both summer and winter

Are you sure you're in the UK?

[duffpkg]

I am absolutely not in the UK. I am in the southwest.