Pv Panel

How much power a one square meter of PV panel produce?
Nowadays, many building featured some PV panels in their roof, wall, etc. Is there any short/fast method to calculate how many panels we need? And is it need a battery room to restore the power?
A battery doesn’t “restore” power, whatever that means, it stores it for times when there is no sun.
The incident energy from the sun is about 1000 watts per square meter at high noon. A solar array at 10-15% efficiency will generate about 100-150 watts per square meter.
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