Home battery storage: questions and answers

It keeps electricity your panels make while the house is not using it, and gives it back later, usually in the evening. Without panels, a battery can fill from the grid in a tariff's cheaper hours instead.

No. The house uses solar first; the battery takes only the surplus, and only until it is full. After that, surplus is exported as it would be without a battery.

Less. On PVGIS figures for Leicester, panels make about 3.88 kWh per kWp on a June day and 1.10 in December. In winter most solar is used as it is made, so a solar-fed battery often has little to store unless it is also charged from the grid.

Yes, on a tariff with cheaper hours, such as Economy 7 or a time-of-use tariff. The battery fills in the cheap hours and runs the house later. It loses a little energy each cycle, and it can only move as much as you use outside the cheap hours.

No. A heat battery stores heat for heating or hot water. A home battery stores electricity. They are different products under different rules.

No. The government's 2026 response on plug-in solar describes plug-in devices as small solar systems without batteries that connect through a household socket. Home battery storage is wired into the home's electrics.

Only with a backup function. The law requires a source running alongside the grid to disconnect when the grid supply is lost, so a standard battery switches off. Backup separates the home from the grid first, then runs chosen circuits.

Divide the usable energy above the reserve by the combined power of what you keep on. Our runtime estimator does it with your own figures, and flags loads above the backup output limit.

No. PAS 63100 lists lofts, roof spaces and voids among the places a battery should not go.

Outdoors or in a separate outbuilding is preferred. Bedrooms, cupboards opening into them, escape routes, lofts and cellars with no way outside are ruled out. Other indoor rooms need fire separation, ventilation to outside and, where rarely visited, an interlinked alarm.

Where it is in a rarely visited place such as a store cupboard, PAS 63100 asks for a smoke or multi-sensor alarm interlinked with the home's other fire alarms.

Under PAS 63100, no more than 20 kWh in one enclosure, and 40 kWh per home in most places, rising to 80 kWh outdoors, in a detached garage or outbuilding, or in a suitably separated garage.

It must always be told. Small systems are notified within 28 days under G98; storage over 3.68 kW needs a G99 application before installation, and the reply can come with conditions.

Not to store solar. You will usually need one for a time-of-use tariff and for export payments, which need half-hourly export readings.

GOV.UK says a battery that can import and export could be used to benefit from the Smart Export Guarantee, but suppliers set their own terms. Ask your export supplier before relying on it.

Yes. Amendment 4 to BS 7671, published in April 2026, added a chapter on stationary batteries, covering inverters, protection, location, ventilation and fire risk.