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Choose a kit from those we priced (or enter your own), your town and how the panels sit. The calculator turns the PVGIS generation into a yearly saving and a simple payback time, then ranks every plug-in kit we priced at your settings.
The assumptions, written out
- Unit rate: 26.32p per kWh, the Ofgem price cap for electricity paid by Direct Debit, average for England, Scotland and Wales, 1 October to 31 December 2026 (Ofgem, read 14 November 2026). Your region and payment method change it: use the figure on your bill. The standing charge does not change with solar, so it is left out.
- Share used at home: 50% by default. It is an assumption, not a measurement of your home. The table below shows where it comes from.
- Export: 0p by default (see the FAQ).
- Payback = kit price / yearly saving [calc], at today's rate, with no price change, no panel ageing, no repairs and no installation cost. It is a snapshot, not a forecast.
How much of the solar a home uses
We ran the PVGIS hourly series for 2021 to 2023 against a constant household baseload (fridge, router, standby: what runs all day and night), capped at 800 W, and counted the share of the solar that the baseload absorbs [calc]. Washing machines or dishwashers run in daylight raise it; being away all day with nothing on lowers it.
| Town | Panels | Kit | kWh/yr | 100 W baseload | 150 W baseload | 300 W baseload |
|---|---|---|---|---|---|---|
| London | south, vertical | 460 Wp | 335 | 65% | 82% | 100% |
| London | south, vertical | 920 Wp | 671 | 41% | 54% | 82% |
| London | south, 35° | 460 Wp | 465 | 57% | 74% | 98% |
| London | south, 35° | 920 Wp | 931 | 34% | 47% | 74% |
| London | east, vertical | 460 Wp | 238 | 70% | 84% | 100% |
| London | east, vertical | 920 Wp | 475 | 49% | 61% | 84% |
| Manchester | south, vertical | 460 Wp | 296 | 68% | 83% | 100% |
| Manchester | south, vertical | 920 Wp | 592 | 44% | 57% | 83% |
| Manchester | south, 35° | 460 Wp | 411 | 60% | 76% | 98% |
| Manchester | south, 35° | 920 Wp | 821 | 37% | 50% | 76% |
| Manchester | east, vertical | 460 Wp | 214 | 73% | 85% | 100% |
| Manchester | east, vertical | 920 Wp | 428 | 52% | 64% | 85% |
| Glasgow | south, vertical | 460 Wp | 292 | 68% | 83% | 100% |
| Glasgow | south, vertical | 920 Wp | 584 | 43% | 57% | 83% |
| Glasgow | south, 35° | 460 Wp | 396 | 61% | 77% | 98% |
| Glasgow | south, 35° | 920 Wp | 791 | 37% | 50% | 77% |
| Glasgow | east, vertical | 460 Wp | 199 | 75% | 87% | 100% |
| Glasgow | east, vertical | 920 Wp | 398 | 54% | 66% | 87% |
How we compare: criteria, sources and dates
Payback for every plug-in kit we priced
London, vertical on a south-facing railing, 50% used at home, 26.32p per kWh. For example, the Octopus Energy two-panel bundle at £650: 683 kWh x 50% x £0.2632 = £89.94 a year, so 7.2 years [calc].
Kit details and our picks: plug-in solar kits in the UK. Would one panel pay back sooner than two? One or two panels.
Frequently asked questions
Why does the share used at home matter so much?
Electricity you use while the panels produce replaces units you would have bought. What you do not use flows out to the grid and, unless your supplier pays for it, earns nothing. A household with a 150 W round-the-clock baseload uses about half the output of a 920 Wp vertical kit in London, from our hourly calculation.
Which unit rate should I enter?
The one on your bill. The default is the Ofgem price cap average for Direct Debit customers in England, Scotland and Wales from 1 October to 31 December 2026: 26.32p per kWh. Ofgem notes there is no VAT on electricity from 1 October 2026 to 31 March 2027.
Can I get paid for what I export?
The official documents we read for plug-in solar do not set an export payment. If your supplier offers one for your setup, enter it; otherwise leave it at zero.