Home › Savings Calculator

UK balcony solar savings & payback calculator

Estimate how much an 800W balcony solar kit could save a UK flat per year — and how fast it pays for itself — at the current energy price cap.

Quick answer: At the current UK energy price cap (~27–28p/kWh) an 800W balcony solar kit producing around 760 kWh/year saves roughly £200/year through self-consumption, so a £500 kit pays back in ~2.5 years and a £1,000 system in ~5 years. Savings come from electricity you do not buy — not from exporting to the grid (SEG is rarely available on plug-in installs).
—
Est. yearly production
—
Est. yearly savings
—
Payback time
Estimates only. Assumes 100% self-consumption — every kWh produced is offset against your supplier’s rate. In practice some daytime production may go to waste if your household is not drawing power at that moment; a battery (Anker SOLIX Solarbank, EcoFlow STREAM Ultra, Zendure SolarFlow) shifts that into evening use. SEG (Smart Export Guarantee) is generally not available for plug-in installs because they lack MCS certification, so we don’t model export income.

Two kinds of email. Nothing else.

Your payback depends on two things that move

The rate you pay changes the savings above. The ENA type test register changes what you are allowed to buy. We email when the second one moves — one email when devices change status on the register, never more than one a week, and one on the day the law changes. Nothing else.

Double opt-in: you get a confirmation email first, and nothing is added to the list until you click it. The numbers you typed above never leave your browser — this calculator runs entirely on your device and we do not see them. See our privacy notice.

How the math works

The calculator uses a deliberately simple, transparent model:

  • Yearly production = system AC watts × production-per-watt (kWh/W/yr). UK middle estimate is ~0.95 kWh/W for a well-placed south-facing balcony, ~0.7 kWh/W for a shaded or strongly east/west install, ~1.1 kWh/W for a tilted unshaded panel.
  • Yearly savings = production × your electricity rate. UK price cap unit rate is ~27p/kWh in mid-2026; fixed tariffs vary £0.04–£0.06 either side.
  • Payback = kit price ÷ yearly savings.

The single biggest lever is your electricity rate, which is why UK plug-in solar payback is much faster than the global average. The 800W cap, plus modest UK insolation (~950–1,100 sun-hours/year in most of England), keeps yearly output around 600–900 kWh — making the £500 kit + ~£200/year savings the sweet-spot for most flats.

Once you’ve modelled the numbers, check our honest 2026 kit picks and the current UK legal status before buying.