What is kWh (Kilowatt-hour)?
A unit of energy equal to using 1,000 watts for one hour — the standard unit on UK electricity bills.
Quick Answer
The average UK home uses approximately 3,700 kWh of electricity per year. Electricity is billed per kWh — typically around 24–34p per kWh depending on supplier and tariff. A 4kWp solar system in the UK generates 3,400–3,800 kWh per year, offsetting a significant portion of household electricity costs.
Fact-checked by John Rooney, Solar Energy Editor. Editorial policy
kWh (Kilowatt-hour) Explained
A kilowatt-hour (kWh) is a unit of energy that represents 1,000 watts of power sustained for one hour. It is the standard billing unit on electricity bills in the UK and worldwide. If your solar panels generate 4 kW of power for 3 hours, they produce 12 kWh of energy. kWh measures cumulative energy production or consumption, while kW measures instantaneous power. Understanding kWh is essential for comparing solar system output to household electricity usage.
How Does kWh (Kilowatt-hour) Work in the UK?
The average UK home uses approximately 3,700 kWh of electricity per year. Electricity is billed per kWh — typically around 24–34p per kWh depending on supplier and tariff. A 4kWp solar system in the UK generates 3,400–3,800 kWh per year, offsetting a significant portion of household electricity costs.
Frequently Asked Questions
How many kWh does a solar panel produce per day in the UK?
A single 400W panel in the UK produces roughly 1–1.5 kWh per day averaged across the year — more in summer (2–3 kWh) and less in winter (0.3–0.7 kWh).
What does 1 kWh of electricity cost in the UK?
Electricity prices in the UK typically range from 24–34p per kWh, depending on your supplier and tariff plan. Time-of-use tariffs may offer cheaper rates at night.
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John Rooney is the founder of Solar Info and has been covering the UK solar energy market since 2023. He fact-checks all content against official MCS and Ofgem data and maintains relationships with MCS-certified installers across the UK.