Kilowatt-hour (kWh)

A kilowatt-hour (kWh) is a unit of energy equal to using 1,000 watts of power for one hour. It is the standard measurement for both solar energy production and home electricity consumption — and it is what your utility company uses to calculate your electric bill.

The average American household consumes approximately 10,500 kWh per year, or about 875 kWh per month. When sizing a solar system, installers calculate how many kWh your panels need to produce annually to offset your electricity usage. A 8 kW solar system in a sunny location might produce 10,000–12,000 kWh per year. Your utility charges you per kWh consumed — the national average is around $0.16/kWh, though rates vary widely by state ($0.10–$0.35/kWh). Understanding your kWh usage is the first step in determining the right solar system size for your home. You can find your monthly kWh consumption on your electricity bill.