Bills have four ingredients: how much heat you lose, how efficiently you make it, what you pay per unit, and what runs unnoticed. Check them in that order.
A leaky home can need twice the energy of an insulated one for the same warmth. Thin loft, unfilled cavities, suspended floors and draughts are the usual suspects — the Heat Loss Calculator scores yours in a minute, and fixes start at £750 (often funded).
An 80%-efficient old boiler wastes £1 in every £5 of gas; heat pumps deliver 3–3.5× the heat per unit (run the comparison). On price: default tariffs, single-rate with an EV, or estimated billing all inflate quietly — submit real readings and compare.
Immersion heaters left on, tumble dryers, old freezers in garages, 24/7 standby — typically £150–£300/year combined. A £10 plug-in monitor finds yours in a weekend.
AC-coupled (battery has its own inverter) is the retrofit default: no rewiring of your array, works with any brand or age of system, £3,500–£6,000 installed for 5–10kWh usable. DC-coupled only makes sense if your inverter is due replacement anyway — a hybrid inverter + battery swap can be cheaper combined.
Feed-in Tariff payments are unaffected by adding storage — generation payments continue and deemed export isn’t metered down. On SEG, a battery lets you shift export into peak-price windows instead.
Match usable capacity to your evening consumption and summer surplus — the sizing guide has the tables. Most 4kWp homes land at 5–8kWh usable.
Space heating (~60%), then hot water, then appliances — which is why insulation and heating efficiency beat gadget-switching.
Yes — estimated readings and faulty meters happen. Submit actual readings and request a meter accuracy check if usage looks impossible.
Draught-seal and drop flow temperature this week; insulate the loft this month; check funding for walls — the checker maps it.
Facts checked 21 August 2026. We link to official sources and show when facts were last verified. If a scheme changes, we update the page.
Free, independent, 60 seconds. We compare every option, check Government scheme eligibility and match you with one trusted local installer if you want one.
Check My Home →