Plug-In Solar Savings: How Much Can You Save in the UK?
Last reviewed: 27 August 2026. Plug-in solar is legal in Great Britain from 27 August 2026 for compliant devices. This page runs the numbers: realistic savings scenarios, SEG income estimates, and payback periods, so you can see whether a kit earns its keep in your home.
£80–£340
Total annual benefit (800W)
~2–3 yrs
Typical payback
600–900 kWh
Annual generation (800W)
1–12p/kWh
SEG export rate range
Tip
The two ways the money comes back
Plug-in solar pays back in two places. Self-consumption is the useful one: every unit your panels make and you use in the home is a unit you do not buy from your supplier, saving the retail price of around 27p/kWh. SEG export income is the smaller pot: power you do not use goes to the grid, and your SEG supplier pays you for it (typically 1–12p/kWh). The retail price is much higher than the export price, so using your own power is where the payback gets moving.
How plug-in solar savings work
Your annual benefit is self-consumption savings plus SEG export income. That sounds tidier than it feels on a real bill, but the idea is simple. Some of the electricity is used in the home, and the rest is exported. The proportion you use directly is your self-consumption rate. If you run the washing machine, dishwasher, or computer in daylight, that rate is usually higher than it is for a home that sits empty all day.
The calculation is not fancy. For every kWh you use yourself, you avoid buying electricity at approximately 27p/kWh in 2026. For every kWh you export, you get whatever SEG rate your supplier offers, usually 1–12p/kWh. A battery can move more daytime generation into evening use, but it adds cost and is outside the first IPS legal route.
Savings scenarios for an 800W system
An 800W plug-in solar kit is normally two 400W panels and a microinverter. In the UK, expect roughly 600–900 kWh a year, with location, orientation, and shading doing their usual mischief. These examples use 27p/kWh for bought electricity and 4p/kWh as a representative SEG export rate.
| Self-consumption rate | Self-use savings | SEG export income | Total annual benefit | Typical household profile |
|---|---|---|---|---|
| 30% (no battery, out all day) | ~£72 | ~£21 | ~£93 | Working household, minimal daytime use |
| 50% (no battery, some daytime use) | ~£121 | ~£16 | ~£137 | Part-time home, weekend laundry |
| 70% (good self-use, timing loads) | ~£170 | ~£10 | ~£180 | Home most days, shifts loads to midday |
| 100% (with battery or heavy daytime use) | ~£243 | ~£0 | ~£243 | Retired or work-from-home, uses all output |
Figures assume 750 kWh annual generation (midpoint of 600–900), 27p/kWh electricity price, and 4p/kWh SEG export rate. Your result will move with household use, tariff, location, orientation, and weather.
400W vs 800W: does kit size matter?
A single-panel 400W kit makes roughly 300–450 kWh per year, about half the output of an 800W two-panel kit. At the same self-consumption rate, it saves about half as much and usually costs about half as much upfront, so payback can look surprisingly similar. I would only jump to 800W if you can use the extra daytime output, say because you work from home or can run appliances during the day. If the house is empty and there is no battery, plenty of that extra output will be sold back at the lower SEG rate.
| Kit size | Annual generation | Kit cost | Annual benefit (50% self-use) | Payback |
|---|---|---|---|---|
| 400W (1 panel) | 300–450 kWh | £120–£250 | ~£70 | ~2 years |
| 800W (2 panels) | 600–900 kWh | £250–£500 | ~£137 | ~2–3 years |
For the less glamorous costs as well as the kit price, see our plug-in solar cost guide.
SEG income estimates
The Smart Export Guarantee pays for electricity you export to the grid. Rates vary by supplier and tariff, from around 1p/kWh on standard tariffs to 12p/kWh or more on specialist export tariffs. The table shows what that means for an 800W system at different export rates and self-consumption levels.
| SEG rate | Export (30% self-use, ~525 kWh exported) | Export (50% self-use, ~375 kWh exported) | Export (70% self-use, ~225 kWh exported) |
|---|---|---|---|
| 1p/kWh (standard) | ~£5 | ~£4 | ~£2 |
| 4p/kWh (typical) | ~£21 | ~£15 | ~£9 |
| 8p/kWh (good) | ~£42 | ~£30 | ~£18 |
| 12p/kWh (best) | ~£63 | ~£45 | ~£27 |
SEG income is the smaller cheque
Even at the best SEG rates, export income is only a fraction of the value of using the electricity yourself. The thing to watch is how much of the generated power you can use in the home before it escapes to the grid. See our SEG registration guide for current supplier rates and the registration steps.
What changes your actual savings?
- The self-consumption rate does most of the work. Running appliances in daylight (washing machine, dishwasher, kettle, computer) can double or triple the saving compared with exporting almost everything.
- Your electricity tariff sets the value of each unit you avoid buying. On a time-of-use tariff (e.g. Agile Octopus), self-consumed solar can be worth 30–40p/kWh during peak hours, which changes the sums quickly.
- Panel orientation and angle matter. South-facing panels at 30–35° generate the most. East- or west-facing panels make about 15–20% less, but they spread generation across the day, which may suit morning or evening use better.
- Location changes the baseline. The south of England generates about 10–15% more than Scotland because irradiance is higher. Use PVGIS for a location-specific estimate rather than guessing.
- Shading is not a small detail. Partial shade from chimneys, trees, or nearby buildings can cut output hard. Microinverters, which are standard in plug-in kits, cope better than string inverters because each panel works independently.
- SEG tariff choice affects the smaller income stream. A higher-SEG-rate supplier increases export income. Some suppliers offer fixed-rate SEG; others use variable or time-of-use export tariffs.
Worked example: a London flat with a balcony
Take a one-bedroom flat in London (postcode area SE) with a south-facing balcony. The owner fits an 800W plug-in solar kit costing £350. They work from home three days a week and set the dishwasher and washing machine for around midday. That puts self-consumption at around 60%.
- Power generated each year (south-facing, 35°, London): ~820 kWh
- Used in the flat (60%): ~492 kWh × 27p = ~£133 saved
- Sent to the grid (40%): ~328 kWh × 4p SEG = ~£13 income
- Annual benefit in total: ~£146
- Time to pay back the £350 kit: ~2.4 years
Worked example: a Manchester semi with a garden
Now compare a three-bedroom semi in Manchester (postcode area M) with a west-facing garden. The owner installs an 800W kit costing £300, ground-mounted in the garden at 30°. They are out at work all day and have no battery, so self-consumption sits around 30%.
- Power generated each year (west-facing, Manchester): ~680 kWh
- Used in the house (30%): ~204 kWh × 27p = ~£55 saved
- Sent to the grid (70%): ~476 kWh × 4p SEG = ~£19 income
- Annual benefit in total: ~£74
- Time to pay back the £300 kit: ~4 years
Move a few loads and the numbers improve
If the Manchester household moved a dishwasher cycle and a washing machine load to weekend midday, self-consumption could rise to 45%. That would increase annual benefit to ~£100 and cut payback to ~3 years.
How plug-in savings compare to rooftop
A 4kW rooftop solar system generates 3,500–4,500 kWh per year, roughly five times more than an 800W plug-in kit, and saves £500–£1,100 per year including SEG. It also costs £5,000–£10,000 installed, so payback is 7–12 years. Plug-in solar wins on upfront cost. At £250–£500, payback is 2–3 years, which is why small kits can make financial sense even though they produce far less electricity. For the full comparison, see our plug-in vs rooftop solar guide.
Questions people ask before buying
Are these savings guaranteed?
No. Savings depend on location, orientation, weather, tariff, self-consumption habits, and SEG rate. The figures here are illustrative and based on UK averages. Use PVGIS for a location-specific generation estimate, then check current SEG rates on supplier websites. That is the boring work that saves disappointment later.
Do I need a battery for the sums to work?
No. A battery can increase self-consumption (from ~30% to ~60%+), but it adds cost and is outside the first IPS legal route for plug-in solar. Most plug-in solar savings come from using power during daylight hours, which you can do by timing appliances without buying a battery.
What SEG rate can I actually get?
SEG rates change often. As of August 2026, standard SEG rates range from 1p to 12p/kWh. Some suppliers offer higher rates on specialist or time-of-use export tariffs. Check our SEG registration guide for current rates, and still verify on the supplier’s website before you sign up.
Will plug-in solar wipe out my electricity bill?
No. An 800W plug-in kit generates 600–900 kWh per year, roughly 15–20% of an average UK household’s electricity use. It should reduce your bill, not make it vanish. A full rooftop system (4kW) can cover most or all of an average household’s annual consumption.
Does seasonality change the payback?
Yes. Solar generation is highest from April to September and lowest from November to February. Most of the annual saving arrives in summer, when the days are longer and the sun is doing more than making the conservatory unbearable. In winter, a plug-in kit may generate only 20–40 kWh per month, enough to offset a little daytime use but not a major saving. Plan appliance use around midday generation in summer if you want to maximise self-consumption.
Run the numbers, then do the paperwork
This page was last reviewed on 24 July 2026. It is guidance, not financial advice. Tariff rates change frequently, so verify them on the supplier’s website before registering.