Is plug-in solar worth it in the UK? Savings and payback, worked out

typical saving, 800 W kit facing south

£70–150 a year

to earn back each £100 of price

8–18 months

GB average unit rate, Oct–Dec 2026

26.32 p/kWh

For your own postcode, direction and usage, use the calculator.

How much does the government say you’ll save?

DESNZ says plug-in solar could be “saving households up to £110 a year” and that a kit can provide “up to 20% of an average home’s electricity use” (DESNZ press release).

“Up to” is doing a lot of work there. The £110 comes from the DESNZ impact assessment (Table 7). It models a home using 3,323 kWh a year with someone in all day:

DESNZ case	Generated	Self-used	Self-used kWh	Saving
800 W, 30° south	690 kWh	62%	428 kWh	≈ £110
800 W, vertical east/west	378 kWh	72%	272 kWh	≈ £70

Both are valued at the July–September 2026 price cap, with nothing paid for exported power.

How we worked out the savings

We use the same approach, with location-specific yields and today’s unit rate:

• Kit: 0.88 kWp of panels (two panels of about 440 W) on an 800 W inverter. At this size the 800 W cap causes no measurable clipping.
• Yield: PVGIS 5.3 (the EU’s solar model), 2005–2023 average, 14% system losses.
• Unit rate: 26.32p/kWh, the GB average price cap for October–December 2026 (Ofgem). It already reflects VAT on electricity falling from 5% to 0% between 1 October 2026 and 31 March 2027 (Ofgem).
• Self-consumption: only electricity you use as it’s generated saves money. We model low, medium and high daytime use as about 33%, 50% and 63% of output used at home. “High” matches DESNZ’s 62%.
• Export: valued at £0 (see export).

Yearly generation, 0.88 kWp kit

City	South, 35° tilt	South, vertical
London	897 kWh	654 kWh
Bristol	900 kWh	650 kWh
Edinburgh	794 kWh	601 kWh
Manchester	780 kWh	569 kWh

Yearly saving at 26.32p/kWh

Case	Low use (33%)	Medium (50%)	High (63%)
London, 35° south	£78	£118	£149
Manchester, 35° south	£68	£103	£129
London, vertical south	£57	£86	£108

Our figures are higher than DESNZ’s. PVGIS gives more sunshine than the SAP model DESNZ used, and our reference kit has slightly more panel than 800 W.

How long does a kit take to pay back?

Simple payback is kit price ÷ yearly saving. Prices change daily, so look them up on in stock or kits, then use this table:

Yearly saving	Months to earn back each £100
£149 (London, high use)	8
£118 (London, medium)	10
£103 (Manchester, medium)	12
£86 (London vertical, medium)	14
£68 (Manchester, low)	18

Multiply the months by the kit price in hundreds of pounds. For example, a kit costing £500 with a £118 saving pays back in about 5 × 10 = 50 months.

This ignores panel ageing (we assume 0.5% less output each year) and future changes to the unit rate, which Ofgem resets every quarter.

What changes the saving most?

1. Daytime use. Going from low to high daytime use nearly doubles the saving. A fridge, freezer, router and anything running while you’re home all count. See best tariffs for ways to shift use into daylight.
2. Direction and tilt. Vertical mounting (a balcony railing or wall) gives about 72–76% of a 35° tilt over a year, but more in winter. See east-west and north-facing.
3. Shade. PVGIS allows for hills on the horizon, not your neighbour’s tree or the balcony above. Every hour of shade comes straight off these figures.
4. Your region’s unit rate. October–December 2026 rates run from 25.36p (East Midlands) to 27.86p (Merseyside and North Wales), so the same kit saves about 10% more in one than the other.
5. Export. Most plug-in kits can’t get the Smart Export Guarantee, which needs an MCS-certified installation (gov.uk). Surplus power usually earns nothing.

When isn’t it worth it?

• You’re in Northern Ireland. The part of SI 2026/848 that permits use doesn’t extend there yet. See Northern Ireland.
• You can’t get permission. Renters and leaseholders need landlord or freeholder consent. See landlord permission.
• Your only spot is heavily shaded. Run the calculator before you buy.

What to do next

Put your postcode into the calculator for a figure for your own setup. Then compare kits in stock by cost per kWh, using the method in cost.