Home / Guides / What size solar and battery do I need?
Sizing
What size solar and battery do I need?
Short answer. A typical house takes 8 to 12 panels, about 3.5 to 5 kWp, and a battery of about 5 kWh. A terrace may only fit 2 to 3 kWp. Size the battery to your evening use, not to the roof.
In this guide
Panels
One panel is roughly 400 to 450W, so 10 panels is about 4 kWp. In our model each kWp makes about 900 kWh a year on a good roof. The Energy Saving Trust says a typical home system is about 4.5 kWp.
By Whitstable house type
- Terrace: 2 to 3.5 kWp. About 15% of households across five Whitstable wards, and 30% in Gorrell.
- Semi: 3.5 to 4.5 kWp. About 31% of households, and 42% in Swalecliffe.
- Detached: 4 to 6 kWp. About 39% of households, 59% in Chestfield and 50% in Seasalter.
- Flat: a roof system is usually a freeholder matter. Plug-in solar may fit.
Battery
5 kWh covers the evening for many houses using about 3,000 kWh a year. 10 kWh suits an electric car, heat pump or high evening use. Costs are in the cost table.
Questions people ask
What does kWp mean?
Kilowatt peak, the most power the panels make in perfect sun.
What does kWh mean?
A kilowatt hour, the unit on your bill. A 5 kWh battery holds five units.
Can I add panels later?
Often, but the inverter must have room. Tell the installer if you plan to.
Want numbers for your own house? Try the estimator or ask for a free quote.
Sources
- Energy Saving Trust: solar panels
- Energy Saving Trust: battery storage
- ONS Census 2021 via Nomis: accommodation type by ward
More guides
- What solar and a battery cost for a Whitstable house
- Solar only, battery only, or both?
- Is a home battery worth it?
- 0% VAT on solar and batteries: what it means
- Smart Export Guarantee: what you are paid
- Planning rules for solar in Whitstable
- Plug-in solar for flats and terraces
- Cheap overnight tariffs and home batteries
- An EV charger with solar and a battery