Does a home battery pay back?
A battery earns its keep two ways: storing your own solar for the evening, or charging cheap off-peak and powering your home at peak rate. Tell us which fits and we will show the maths, losses included.
Assumes 90% round-trip efficiency and ~300 useful cycles a year.
Where a battery's value comes from
With solar. Without storage, a typical home uses about 30% of what its panels make and exports the rest. A battery soaks up daytime surplus for the evening, so that energy is now worth your import rate minus the export rate you gave up. We cap the gain at the surplus available and at your evening demand.
Battery only. On a tariff with a cheap night rate, you charge the battery off-peak and run the house from it during the day. Each unit shifted is worth the peak rate minus the off-peak rate, after a 10% round-trip loss.
The verdict. Cost uses about £500 per usable kWh plus install. Storage often pays back slowly today; it makes most sense alongside solar, a cheap night rate or an EV. We flag whether payback lands inside a typical 10-year warranty.