Climate Policy

[Zenda]

It is not a mathematical derivation, just a "rule of thumb". Which is why I said, "The usual formula for figuring peak watts needed is to take Watt Hour per Day divided by 4." If you take WH per day / 4 you get an approximation for system peak watts.

Sure, but why do you want to compare peak consumption with total daily production? You could compare peak consumption with maximal output, but that propably doesn't make much sense unless we know that peak production is during the same period as peak consumption. You took the effort to calculate daily production, so we should compare with daily consumption. No dividing by 4 is needed here, and we would arrive at 377 Watts or 377/23 = 16.4 m2. This almost looks plausible B)

Taken from this site. Which is pro-solar.

Apparantly, being pro-solar doesn't keep them from making blunders. They say it's colder up north because the distance to the sun would be greater. Luckily, they rely on others for the actual data and calculations :mellow:

Still, 24m2 to make up for 20 kWh/day electricity consumption is not enough.

You could have saved yourself all these calculations, by looking at the link given by Jester. In the UK, where sunshine is comparable or less as in the most sunless states of the US, daily output would be 5 kWh for every 10 m2. So, to cover for your 20 kWh per day, we'd need 40 m2.

Ofcourse, like you said earlier, a hybrid solution would be best. If we'd want to offset half of your electricity consumption, we'd need 20 m2, which seems to fit nicely on your roof.