The short answer
A compliant 800 VA kit with about 900–1,000 W of panels generates 650–850 kWh a year south-facing and tilted, or around 650 kWh vertical. At 26.32p/kWh and 60% self-use that is £100–£135 a year. Payback is 4–8 years for kits priced £450–£850, against a 20-year panel life. Shade, a north-facing site, or nobody home in the day can halve the saving.
1,000 W kit, south tilt, per year
same kit, vertical balcony
saving/yr at 60% self-use, tilted
payback on a £600 kit
Generation by orientation (per 1,000 W of panels, 800 VA inverter)
| Orientation | kWh / year | Saving at 60% self-use | Saving at 40% | Saving at 80% |
|---|---|---|---|---|
| South, tilted 25–35° | 800 | £126 | £84 | £168 |
| South, vertical (balcony rail) | 650 | £103 | £68 | £137 |
| East or west, vertical | ≈ 600 | £95 | £63 | £126 |
| North | ≈ 350–450 | £55–£71 | £37–£47 | £74–£95 |
Figures are PVGIS-based estimates for a central-England location; London runs about 5% higher and Edinburgh about 15% lower. A 890 W kit scales to 89% of these numbers, a 460 W kit to 46%.
Payback for typical kit prices
| Kit price | Saving £103/yr (vertical) | Saving £126/yr (tilted) | 20-year net, tilted |
|---|---|---|---|
| £450 | 4.4 years | 3.6 years | +£2,070 |
| £600 | 5.8 years | 4.8 years | +£1,920 |
| £850 | 8.3 years | 6.7 years | +£1,670 |
The 20-year figure assumes the unit rate stays at today's cap; electricity prices have risen faster than inflation over the past decade, which would shorten payback, and ignores inverter replacement around year 12 (£100–£200).
What self-use really means
A plug-in kit feeds your sockets; whatever your home is not using at that moment flows out to the grid, unpaid in nearly all plug-in installations. A fridge-freezer, router, standby devices and a laptop draw 100–300 W through the day, which absorbs most of a kit's output on an average day but not its summer peaks. Running the dishwasher, washing machine or an EV charger at midday lifts self-use towards 80%. If the house is empty 8 am to 7 pm, assume 30–40% and halve the savings above.
Winter reality
UK solar is seasonal: roughly 70% of a year's output comes between April and September. A 1,000 W kit might make 120–140 kWh in July and 20–30 kWh in December. It will not run an electric heater in winter — see our heater guide for what that costs — but it will run the fridge and the background load from spring to autumn.
Rules in one paragraph
Great Britain only, from 27 August 2026: a plug-in solar device must be on the ENA Type Test Register, limited to 800 VA and 3.5 A, use a non-rewireable BS 1363 plug fused at 5 A or less, have no battery in the plug-in device, with one device per household; the installer sends a G98 Form B to the network operator within 28 days. Permitted development rules for England were updated by SI 2026/896 so no planning permission is needed in most cases. Flats: check the lease and freeholder for balcony mounting.
Yearly output and savings of the kits we list
| Product | Yearly output, south-facing tilt | Yearly output, vertical balcony | Saving per year, tilted (60% self-use) | Saving per year, vertical (60% self-use) |
|---|---|---|---|---|
| UKSOL Plug-in Solar 890 W Pro Duo, ground-mount kit (2 × 445 W, 800 W inverter) | 712 kWh | 578 kWh | £112.44 | £91.36 |
| EcoFlow STREAM 800 W microinverter with 2 × 500 W panels | 800 kWh | 650 kWh | £126.34 | £102.65 |
| UKSOL Pro Compact 460 W kit with 800 W microinverter, ground mount | 368 kWh | 299 kWh | £58.11 | £47.22 |
Payback calculator
saved per year
years to pay back
net over 20 years
Frequently asked questions
Does plug-in solar work on a north-facing balcony?
Poorly — roughly half the output of a south-facing one, so a saving of £50–£70 a year on a 1,000 W kit. Payback stretches past ten years; it is rarely worth it unless the kit is very cheap.
Can I get paid for exported electricity?
In principle the Smart Export Guarantee applies to MCS-certified installations, which plug-in kits generally are not. Assume no export payment and maximise self-use instead.
Will plug-in solar cut my standing charge?
No. The standing charge (54.83p a day under the current cap) is paid regardless of consumption. Plug-in solar reduces only the unit-rate part of the bill.
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