Estimate

Plug-in solar savings and payback

Type the kit price, the panel watts, the orientation, the shade, how much of the power you use at home, and your unit rate. The rate starts at the configured Ofgem cap figure, 26.32p/kWh.

Estimate

Kit price, pounds Panel watts Orientation Shading Share you use at home, percent Unit rate, pence per kWh

26.32p/kWh is the site config for the Ofgem cap unit rate. Ofgem energy price cap, Direct Debit electricity unit rate, 1 October to 31 December 2026, average for England, Scotland and Wales. Electricity VAT is 0% in this period, so this rate does not add VAT. Energy Saving Trust puts a UK-compliant 800W plug-in device at about 700 kWh a year. Orientation and shading scale that figure. This is an estimate, not a survey of your home and not an MCS quote.

Estimate: about 350 kWh a year, 175 kWh used at home, about £46.06 a year, simple payback about 8.7 years.

Working

Watts modelled: 400 W, within the 800 W cap = 400 W
Annual generation: 700 kWh × (400 / 800) × 1 South × 1 Little or none = 350 kWh
Used at home: 350 kWh × 50% = 175 kWh
Not counted: 350 − 175 kWh. No export rate is applied. = 175 kWh
Annual saving: 175 kWh × 26.32p = £46.06
Simple payback: £400.00 ÷ £46.06 = 8.7 years

Sources

Plug-in solar rules. A compliant plug-in device is limited to 800W into the home, and one device per home. This estimate models one device and does not use watts above that cap.
About 700 kWh a year at 800W. Energy Saving Trust puts a UK-compliant 800W plug-in device at about 700 kWh a year. Orientation and shading scale that figure. This is an estimate, not a survey of your home and not an MCS quote.
Unit rate. The form defaults to 26.32p/kWh. Ofgem energy price cap, Direct Debit electricity unit rate, 1 October to 31 December 2026, average for England, Scotland and Wales. Electricity VAT is 0% in this period, so this rate does not add VAT. Type your own rate if your tariff differs.

This is an estimate for one plug-in device in Great Britain. It is not a quote, a survey, or a promise of savings. Electricity you do not use at home is not given an export payment in this sum.

One device per home. The model caps the watts at 800. It does not apply in Northern Ireland. Read the guide.