kWh (Kilowatt-hour) explained
A kilowatt-hour (kWh) measures energy — the total amount of electricity consumed or produced over a period of time. If a 1 kW solar panel runs for one hour in full sunlight, it produces 1 kWh of electricity.
Your electricity bill is priced in pence or cents per kWh. In the UK, the average unit rate is around 24–28p per kWh (as of 2024–2026). In the US, it averages around $0.13–$0.17 per kWh, though this varies significantly by state.
When comparing solar quotes, installers will estimate your system's annual output in kWh. A 4 kW system in the UK typically produces around 3,400–3,800 kWh per year, while the same system in Arizona might produce 6,000–7,000 kWh per year due to higher solar irradiance.
- Average UK home consumption: 2,700–3,500 kWh/year
- Average US home consumption: 10,500 kWh/year
- EV adds roughly: 2,000–4,000 kWh/year
Understanding kWh helps you match your system size to your actual usage, maximise self-consumption, and accurately calculate your payback period and savings.