Balcony solar panels work in a UK winter, but they will not produce their summer output. Our PVGIS model gives a 600 Wp south-facing vertical array in London about 85 kWh across December, January and February. At 26.32p/kWh and 60% self-consumption, that is roughly £13 off an electricity bill across those three months. It is a modelled example, rather than an owner's result.
The useful question is how the whole year compares with the fitted cost. Winter is part of that calculation, rather than a reason to assume panels stop working. Our monthly savings calculator lets you change the region, direction, angle, tariff and share of generation you use.
Do solar panels work in a UK winter?
Yes. Plug-in solar panels generate electricity from daylight, and the model below includes the lower radiation available in winter. A panel's rated watts describe its output under test conditions, rather than the power it supplies continuously. A 600 Wp balcony solar system will spend much of a winter day well below that rating. Buying more capacity does not turn a short winter day into a long summer one.
How much does balcony solar generate each month?
The table compares the same 600 Wp array facing south in London: hung vertically at 90° from horizontal, or tilted at 35°. Both use 14% system losses and the PVGIS-SARAH3 radiation database. Buildings, balcony overhangs and nearby trees are not included in the terrain horizon.
| Month | Vertical balcony, 90° | Tilted panels, 35° |
|---|---|---|
| January | 27.6 | 24.4 |
| February | 31.7 | 31.9 |
| March | 42.6 | 51.9 |
| April | 46.2 | 68.7 |
| May | 40.0 | 71.7 |
| June | 37.8 | 73.6 |
| July | 39.4 | 73.9 |
| August | 41.0 | 66.2 |
| September | 43.5 | 57.1 |
| October | 38.1 | 41.1 |
| November | 31.9 | 28.9 |
| December | 26.0 | 21.8 |
| Full year | 445.7 | 611.3 |
| December–February | 85.3 | 78.1 |
For this example, winter accounts for about 19% of the vertical array's annual generation, compared with 13% for the tilted array. Monthly figures are rounded individually, so their displayed sum can differ slightly from the annual figure.
Does vertical mounting help in winter?
It can. A south-facing vertical panel meets the low winter sun more directly than a shallow panel. In this London model, the vertical array makes 85.3 kWh over December–February against 78.1 kWh at 35°. Over the full year, the tilted array produces more: 611 kWh against 446 kWh.
That is a comparison of two angles at one location, rather than a promise that every vertical installation wins in winter. A slab overhead, a solid parapet or a neighbouring building can remove the direct sunlight the panel needs. For a north-facing railing the result is very different; use our north-facing balcony guide and the calculator before committing.
London, Manchester, Edinburgh and Cardiff compared
These examples use 600 Wp of south-facing panels at 90°. They represent the named city coordinates, rather than every property in the region.
| City | Annual output | December–February output |
|---|---|---|
| London | 446 kWh | 85.3 kWh |
| Manchester | 388 kWh | 65.7 kWh |
| Edinburgh | 409 kWh | 67.6 kWh |
| Cardiff | 447 kWh | 79.4 kWh |
What is the winter electricity worth?
Electricity saves you its unit price only when you use it instead of buying from the grid. This example values the London vertical array's 85.3 kWh of winter output at 26.32p/kWh:
| Share used at home | December–February bill saving |
|---|---|
| 40% | £8.98 |
| 60% | £13.47 |
| 80% | £17.96 |
The percentages are sensitivity scenarios. We have not measured how much an average household uses. The example excludes export income and batteries, and a different electricity tariff changes it. Being at home during daylight can help you use generation, but moving appliance use only makes sense when it suits the household.
Generation is different from electricity-bill saving
The inverter feeds the home while the panels are generating. Some electricity can go straight to appliances, and any surplus goes to the grid. Only the portion replacing electricity you would otherwise buy creates the saving shown here. A graph showing 10 kWh generated does not establish 10 kWh of avoided imports. To check a real solar system, you need generation and import/export records together.
Rooftop solar and a small plug-in solar system can therefore show different self-use percentages even in the same house. A larger array can generate a bigger surplus. This article does not assume an export tariff: our export payments guide explains the paperwork and installation differences.
Should you buy balcony solar in autumn or wait until spring?
Buying in autumn gives you the winter generation above if the kit is delivered, installed and operating. Waiting avoids tying up money before the more productive months. Neither choice makes a poor position or an expensive installation pay back quickly.
- Check the whole-year estimate. Use your actual aspect and mount, rather than a summer advertising figure.
- Compare the complete cost. Include delivery, brackets, suitable fixings and any work needed. Our cost guide separates the kit price from the extras.
- Confirm what you can buy and fit. Use the verified kits tracker, then check the delivery date and manufacturer's mounting instructions.
- Think about access. A winter installation on an exposed balcony may be less convenient. Ask for help when access, weight or mounting safety is uncertain.
A battery is a different installation
Shade, snow and winter maintenance
The low sun makes surrounding obstructions important. Look at where sunlight actually reaches the proposed panel position in the morning, around midday and in the afternoon. A summer photograph is not enough to establish winter exposure.
Follow the kit's instructions for inspection and cleaning. Do not lean over a railing, climb onto an unsafe roof or scrape a panel with a sharp tool to recover a small amount of generation. Check that the mount remains secure after bad weather; our wind and mounting guide explains what to ask the supplier.
Our method and its limits
Comparing the estimate with your own readings
If you already own a solar kit, record its monthly generation alongside the panel rating, direction and angle. Note periods when it was switched off, shaded unusually or covered, and keep the meter or app export rather than only a screenshot of its best day. Compare the same complete months. One dull week or one sunny afternoon cannot establish the long-term output.
For a publishable case study we also need the installation cost, whether the property is owned or rented, and permission to use the photos and figures. You can contribute an installation example. We will describe owner measurements separately from the climate model and agree attribution before publishing them.
We queried the European Commission's PVGIS 5.3 API on 30 September 2026. The full dataset covers twelve UK cities, six directions and three angles. Each simulation uses 1 kWp of crystalline-silicon panels, free-standing mounting, 14% system losses, the default terrain horizon and PVGIS-SARAH3. Energy is scaled to 0.6 kWp for this article. Those losses are already inside the PVGIS output.
For the London example the coordinates are 51.5074, −0.1278, with aspect 0 and angle 90 or 35. The downloadable data and reproduction guide provide all the monthly values. The official PVGIS API documentation explains the parameters.
This is a long-term climate model. It does not forecast this winter, simulate nearby buildings, measure a particular kit or certify its installation. An inverter below the panel rating can clip output; these examples do not include a separate clipping model. Check a site-specific estimate if the buying decision depends on a few pounds a year.