Ten minutes, no tools: check your loft depth, wall type and floor — then let the calculator turn findings into a costed, funding-checked plan.
Loft: tape measure at the hatch — under 270mm = top-up territory; under 100mm = priority. Walls: post-1930 brick in stretcher bond → likely cavity (look for filled drill marks ~1m apart = already done); pre-1930 or 230mm solid brick pattern → solid wall. Floors: ground-floor air bricks outside + bouncy boards = suspended timber, insulatable. Feel test: cold internal wall surfaces and draughts at skirtings tell you where heat runs.
Feed the answers into the Heat Loss Calculator for priorities, then the Whole-House Calculator for costs. EPC D–G? The funding checker maps ECO4/WH:LG routes before you spend anything.
Scheme applications include a retrofit assessment at no cost — a surveyor measures exactly what your home needs. Our one-installer promise applies: no call-centre round-robin, ever.
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.
Measure loft depth at the hatch, check brick pattern for wall type, look for cavity-fill drill marks, and check for floor air bricks — the 10-minute check above walks it.
270mm is the UK standard — under 150mm and a top-up pays back in 2–3 years.
Yes — ECO4 and WH:LG applications include a funded retrofit assessment for eligible households.
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.
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