Do you need a battery?

When a home battery pays its way, when it doesn’t, and how to size one from your bills rather than a brochure.

A warm family kitchen at dusk with the lights on, a dishwasher door open, and a small round energy display glowing on the wall by the door

A battery is the most common thing people ask about, and the one we most often talk them down on.

When it pays

If you’re out at work, the panels make most of their power while the house is empty. A battery keeps it for the evening. With an electric car or a cheap overnight tariff, it earns its keep in winter too.

When it doesn’t

If someone is home all day and runs the washing at lunchtime, you may already use most of what the roof makes. A battery then has little to store.

How big

Look at what you use between five in the evening and midnight. For most homes that’s 4 to 8 kWh, which is why we fit far more 5 and 10 kWh batteries than 15. A battery that never empties is money on the wall.