Question

how much power can you get from the sun, and how much do you need for our use?

Answer 1

At any moment, the sun emits about 3.86 x 10²⁶ watts of energy

Most of that energy goes off into space, but about 1.74 x 10¹⁷ watts or J/s strikes the earth.

If there are no clouds in the way, then one square meter of the earth will receive about 1.4kW per m² of that energy. The rate at which energy reaches the earth's surface from the sun, usually taken to be 1,388 watts per square metre which is called solar constant. So for the 5 hours in the middle of a sunny day, an area the size of a small backyard swimming pool (50 m²) will receive about 350 kilowatts of energy. That’s nearly 12 times what the average US household uses in an entire day! (In the United States, the average daily electricity use is around 30 kilowatt hours per household).

world primary energy consumption rose to 583.90 Exajoules (EJ) or 583.90X10¹⁸ joules for whole year and earth receives energy from the sun 1.74 x 10¹⁷ watts or J/s X365 days/year  X  24 hours/day X 3600 sec/hr.

Total world electricity production was 20,261 TeraWatt hours (TWh) in 2008