People say "kWh" and "kW" as if they mean the same thing, but they don't. kW (kilowatts) is power — the rate energy flows right now. kWh (kilowatt-hours) is energy — the total amount used or produced over some time. To move between them you need the time period, because kW = kWh ÷ hours (and, in reverse, kWh = kW × hours).
A worked example
Say a battery delivers 10 kWh of energy and you want it to last 5 hours. The average power it can supply is 10 ÷ 5 = 2 kW. Spread that same 10 kWh over 10 hours instead and the average power drops to 1 kW. The energy is the same; the power depends entirely on how quickly you use it.
Going the other way: kW to kWh
To find energy from power, multiply by time: kWh = kW × hours. A 3 kW load running for 4 hours uses 3 × 4 = 12 kWh. This is exactly what your electricity meter counts — it bills you per kWh, not per kW.
Why it matters for solar
Solar sizing lives on this conversion. Your daily consumption is in kWh, but panels and inverters are rated in kW (or W). Peak sun hours act as the "time" that links them: array size (kW) × peak sun hours × a loss factor gives your daily kWh. Get the two units straight and the rest of the design follows.
Related tools
Turn energy into a system size with the energy production calculator and the solar panel calculator. For batteries, see the Ah ↔ kWh converter and the battery runtime calculator. To total your loads, use the daily load calculator.
Frequently asked questions
How do you convert kWh to kW?
Divide energy by time: kW = kWh ÷ hours. For example, 10 kWh over 5 hours is 2 kW.
What is the difference between kW and kWh?
kW is power (the rate now); kWh is energy (the total over time). A 2 kW device for 3 hours uses 6 kWh. Bills are per kWh.
How do you convert kW to kWh?
Multiply power by time: kWh = kW × hours. A 3 kW load for 4 hours uses 12 kWh.