Plug-in solar · Generation
How much electricity does 800W plug-in solar generate?
Modelled figures for Great Britain — per year, per day and by season — and what pushes your own result up or down.
By Mike · Updated 25 September 2026 · 9 min read
How much does 800W plug-in solar generate?
Roughly 500 to 900 kWh a year — depending mostly on which way the panels face and how they’re mounted.
That’s our modelled range for 800W of panels across Great Britain, from a vertical balcony mount in the north of Scotland to a well-angled, south-facing frame in south-west England. Averaged over the year, it works out at about 1.3 to 2.5 kWh a day.
The Energy Saving Trust puts a typical 800W plug-in solar system at around 700 kWh a year, for panels in Manchester facing south at 30° with no shade. These are estimates, not guarantees — shade, the weather in a given year and the kit itself all move the real figure.
What changes the figure
Which way it faces
The mounting angle
Shade
Where you live
Panel capacity
That year’s weather
The terms
What “800W” actually means
“800W” is a power rating — how fast electricity can flow at a single moment. What you get over a day or a year is energy, measured in kilowatt-hours (kWh). Even running flat out at 800W for a whole hour, a system would make 0.8 kWh.
Under the plug-in solar rules, the limit sits at the inverter — the box that turns the panels’ DC electricity into mains AC. The government’s product specification says a device can supply no more than 800VA (volt-amperes) to your home’s wiring, measured as the highest 10-minute average, and no more than 3.5A. Because real power in watts can’t exceed apparent power in VA, that also caps the output at 800W.
The panels themselves can add up to more. The specification allows up to 2,000W of panels in total. Above 960W, manufacturers must advise buyers to consider a professional assessment of their home’s electrics before installing. Some kits advertised as 800W have more than 800W of panels — two 440W panels, for example.
The figures on this page are for 800W of panels. If a kit has more, see More panels than 800W.
By location
What 800W of panels could generate in a year
Modelled annual generation for 800W of panels with no shade, in two common set-ups. Figures are in kWh a year, rounded to the nearest 10.
Place
South, 35°
Vertical, south
Plymouth
900
640
Cardiff
830
600
London
820
590
Birmingham
770
570
Manchester
710
520
Newcastle
760
570
Glasgow
680
510
Aberdeen
710
540
Inverness
650
480
South, 35° — tilted on a frame, for example in a garden. Vertical, south — hung on a balcony railing or wall. With one panel facing east and one facing west, both at 35°, the same places come out at about 510 to 710 kWh.
Further south usually means more, but not always: Newcastle beats Manchester in the model, and Aberdeen matches it, because local cloud matters as well as latitude. The bigger difference is the set-up — moving the same panels from a south-facing frame to a vertical railing costs about a quarter of the year’s output almost everywhere.
Per day, that averages about 1.8 to 2.5 kWh for a south-facing frame and 1.3 to 1.8 kWh for a vertical mount. To model your own address, try the free PVGIS tool from the European Commission’s Joint Research Centre.
Through the year
Summer v winter
About 70% of a south-facing system’s year arrives between April and September. Winter days are short and the sun is low, so December output is a fraction of June’s.
South, 35° · kWh a day
June
Dec
London
3.3
0.9
Manchester
3.0
0.7
Glasgow
2.9
0.5
Inverness
2.9
0.4
Vertical panels even things out. Hung facing south, they make much less in summer but slightly more in midwinter, when the sun is low — in London, about 1.1 kWh a day in December against 0.9 for the same panels tilted at 35°.
An east–west split does the opposite: 75 to 81% of its year comes between April and September, and a December day can average as little as 0.1 to 0.4 kWh. From one year to the next, the model’s annual totals typically vary by around 3 to 5%.
Set-up
Direction, angle and shade
How each set-up compares with the same 800W of panels facing south at 35°, modelled for London, Manchester and Glasgow:
South, 60° (steeper)
about 4% less
South-east or south-west, 35°
about 5–7% less
South, 15° (shallower)
about 6–7% less
Flat
about 16–17% less
East or west, 35°
about 20% less
Half east, half west, 35°
about 20% less
Vertical, facing south
about a quarter less
North, 35°
about 45% less
Vertical, facing east or west
about half
Our figures assume no shade from buildings, trees, a balcony above or the railing itself — PVGIS allows for hills on the horizon, but nothing closer. Regular shade will cut output, especially around the middle of the day, and how much depends on how much of each panel it covers and for how long. Watch your chosen spot through a sunny day before you buy.
Bigger kits
More panels than 800W
Because the limit is on the inverter’s output, extra panels still add generation — mostly in the mornings, evenings, winter and dull weather, when panels are nowhere near their peak.
Panels · London, south, 35°
kWh a year
Lost to the limit
800W
about 820
none
960W
about 980
almost none
1,200W
about 1,200
about 2%
2,000W
about 1,670
about 18%
That’s from PVGIS hourly data for 2019 to 2023, with each hour capped at 800W. Hourly averages hide short peaks, so the real loss to the limit will be a little higher. Above 960W, the specification requires manufacturers to advise buyers to consider a professional assessment of their home’s electrics before installing — so look at the total panel wattage a kit is sold with, not just the “800W” on the box.
Generation v savings
Generated isn’t the same as saved
Your bill only falls when your home uses the electricity at the moment it’s made. Anything you don’t use flows out to the grid — and for plug-in solar, that’s normally unpaid, because most suppliers need an MCS certificate before they’ll pay for exported electricity.
The Energy Saving Trust’s example shows the gap. For around 700 kWh generated a year, it estimates savings of about £100 for a household that’s home all day and £70 for one that’s out, at 24.7p per kWh. By our arithmetic, that means roughly 400 and 280 kWh of the output being used in the home.
That’s why when it’s generated matters as much as the yearly total. For whether it makes sense for your home, see Is plug-in solar worth it in the UK?
Before you buy
Using these figures to compare systems
01
Start with where it will go
Decide on the spot first — railing, wall or garden frame — then read across the matching column above.
02
Check the angle you can actually get
An adjustable frame lets you tilt the panels; a railing mount usually means vertical. Angles around 35° did best in our modelling.
03
Look past the “800W” label
Check the total panel wattage as well as the 800VA inverter limit. Two kits both sold as 800W can have different amounts of panel.
04
Make sure it’s compliant
Only buy a system listed as compliant on the official ENA register. How to check.
Good to know
Common questions
How much does 800W of solar generate per day?
In our modelling, about 1.3 to 2.5 kWh a day on average across the year in Great Britain. A June day averages around 3 kWh for a south-facing frame; a December day can be well under 1 kWh.
Will it produce 800W all day?
No. 800W is the ceiling on its output, measured as the highest 10-minute average, and most of the time output is well below that. In our hourly model for south-facing panels in London, the typical daylight hour averaged about 140W, and even the best hours stayed around 700W.
Does plug-in solar work in winter?
Yes, but much less. In December, 800W of panels facing south at 35° makes roughly 0.4 to 0.9 kWh a day in our modelling, from Inverness to London. See Does plug-in solar work in winter? for month-by-month figures and how much winter days vary.
Is a balcony or a garden better?
For the most electricity over a year, a tilted, south-facing frame. Hung vertically on a balcony, the same panels make about a quarter less over the year — though a little more in midwinter.
Has WattVerdict measured this?
No. These are modelled estimates from PVGIS, cross-checked against the Energy Saving Trust’s figure — not measurements from our own testing.
Method
How we worked these out
All figures come from PVGIS 5.3, the European Commission Joint Research Centre’s solar model, run on 25 September 2026. They’re modelled estimates, not measurements.
Panels: 800W (0.8 kWp) crystalline silicon, fixed and free-standing
System losses: 14%, the PVGIS default for wiring, inverter and other losses
Weather: PVGIS-SARAH3 sunlight and ERA5 temperature data, averaged over 2005 to 2023
Shade: hills on the horizon only — no buildings or trees
Places: city-centre points in Plymouth, Cardiff, London, Birmingham, Manchester, Newcastle, Glasgow, Aberdeen and Inverness
Set-ups: south at 15°, 35°, 60° and vertical; south-east and south-west; east, west and a half-and-half split; north; vertical east and west
Bigger kits: PVGIS hourly data for London, 2019 to 2023, each hour capped at 800W
Rounding: yearly figures to the nearest 10 kWh, daily figures to one decimal place
Panels clamped to a railing or wall can run hotter than free-standing ones, and real kits won’t match the default losses exactly — so treat these figures as a guide rather than a forecast for your home.
Sources
Where this information comes from
PVGIS — Photovoltaic Geographical Information System
European Commission Joint Research Centre · the solar model behind our figures (version 5.3).
Energy Saving Trust · its generation and savings estimates and method, updated 17 September 2026.
Plug-in Solar Device Interim Product Specification, version 2.0
GOV.UK · the 800VA, 3.5A and 2,000W limits, clause 4.1, July 2026 (PDF).
Sources checked 25 September 2026.
Related questions
The straight answer
Is plug-in solar worth it in the UK? →
When it makes sense, when it doesn’t, and what to check.
Before you buy
How to check if a plug-in solar system is compliant →
Find the exact model on the official register.
Next step
Know your spot? Compare compliant systems
See which plug-in solar systems are listed as compliant on the official register, and compare prices where we’ve verified them.