Battery or no battery? An honest maths lesson

A battery is the most common upgrade question we get. The honest answer depends on three numbers: your tariff spread, your solar and your evening usage.

The tariff spread

If your cheapest and most expensive half-hours are 20p apart, a 10 kWh battery can save around £2 a day.

The verdict

For most homes with solar and a smart tariff, payback lands between six and nine years.