Solar panels generate electricity during daylight hours. Your home uses what it needs at that moment. What happens next depends on your system and controls.
1. Your home uses solar as it is generated
Solar electricity can supply appliances, lighting and other loads. When demand is greater than generation, your home still draws electricity from the grid, or a charged battery where one is fitted.
2. Surplus energy can be stored
A compatible battery can take some of the solar energy that would otherwise be exported. It can then supply electricity later, within its available charge and power limits. Charging and discharging involve energy losses.
3. The rest can be exported
When generation exceeds what your home and battery can take, surplus electricity can flow to the grid, subject to any export limit. An eligible export tariff can pay you for this electricity.
4. Your tariff changes the calculation
A unit of energy used at home may avoid an import charge; a unit exported may earn income. Which is worth more depends on your rates. Off-peak battery charging can add another option, but you need to consider losses, tariff terms and equipment costs.
Should you always add a battery?
No. The right choice depends on your usage pattern and the economics. Compare solar-only and solar-plus-battery proposals on the same assumptions, including purchase cost and equipment life.
Further reading: Energy Saving Trust: energy storage.
Will it work during a power cut?
Do not assume that having solar and a battery provides backup. Ask whether compatible backup equipment and the circuits it will serve are included in the design. Available energy and output limit what can run. See our battery installation guide.
What should I compare in a proposal?
Compare solar-only and solar-plus-storage options using the same household demand and tariff assumptions. Ask what happens when the battery is full or empty, and how controls prioritise the home, storage and exports. Our system options guide helps compare the scope.
Reviewed 9 September 2026. General guidance; your installation and any scheme requirements need individual assessment.
Talk about my home