Glossary
Price cap
Ofgem's quarterly limit on the unit rates and standing charges suppliers can charge on default energy tariffs in Great Britain.
The energy price cap is set by Ofgem each quarter. It limits the unit rate (pence per kWh) and daily standing charge that suppliers can charge on default tariffs, and it varies by region. It covers Great Britain only; Northern Ireland has a separate regulator.
For October to December 2026, the GB average electricity unit rate for Direct Debit customers is 26.32p per kWh, with a standing charge of 54.83p per day (Ofgem). These figures include 0% VAT, because the government cut VAT on electricity bills from 5% to zero from 1 October 2026 to 31 March 2027 (Ofgem letter).
For plug-in solar, the unit rate is what counts. Each kWh from your kit that you use yourself saves you the unit rate. The standing charge doesn’t change, however much solar you generate. Our calculator uses the cap unit rate for your region by default. If you’re on a fixed or time-of-use tariff, enter your own rate, because your savings could be quite different.