If a home requires 3000 watts of electrical power how many square feet of photovoltaic solar cells would you need to power it?

Answer 1

Photovoltaic cells are variable but a standard 1.6 square-metre (18 square feet) cell as used on roofs in the the UK is rated at 220 Watts. For 3 kW you would need 14 of them.

When installed and switched on in strong sunlight they would produce 3kW that is available to you to use, but, if you don't happen to use as much, the excess power goes back into the supply network, and the result is that your local power station will produce that much less electrical power. The boiler will be told (automatically) to throttle back and produce less steam, so it will consume fuel more slowly and send CO2 up the exhaust pipe at a lesser rate.

So your solar panels produce an immediate reduction in CO2 emissions, because the energy used in everyone's house has to be generated at the instant it is used.

Answer 2

I have a solar panel, and if it is aligned perfectly perpendicular to the sun's rays, and there are no clouds, I can get 75 Watts per square meter out of it. So that's about 7.5 Watts per square foot, so you would need 400 square feet to get 3000 Watts. Note that it generates electricity only during direct sunlight. Which even on sunny days, the sun is high enough to be usable on average 4-6 hours a day. So if you need 24h/day continuous 3000 W then you need at least 2000 square feet. Then how many days in a year are really sunny? If you need 3000 W every day, and 80% of your days sun is behind the clouds, your would need about 10000 square feet. That's about how much you need for continuous average 3000 W. Of course you need batteries to keep the electricity for nights and cloudy days.