Solar Through the Seasons: What Your Panels Really Produce in Winter, and How to Use More of Them

August 7, 2026

If you have panels, or you are thinking about them, this is the number that surprises people most: your solar system will produce roughly four times as much electricity in May as it does in December. That is not a fault, and it is not a badly designed system. It is simply how the sun behaves at northern European latitudes.

The good news is that the seasonal swing is entirely predictable, and there are simple habits that make your panels worth noticeably more without spending anything at all.

What the solar year actually looks like

Measured per kilowatt-peak of installed capacity, a typical UK system produces around 119 kWh in its best month, May, and around 29 kWh in December^[1]. Put another way, a well-sited system generates roughly 20 to 30% of its peak summer output during winter^[2], and the whole November to January stretch usually delivers only about 10 to 20% of the annual total^[3].

For whole-system numbers, a typical 4 kWp installation produces somewhere between 3,400 and 4,200 kWh a year, and a 6 kWp system around 5,400 kWh^[4].

If you live in Germany, these figures translate well, because the UK's annual solar resource is broadly comparable to Germany's. That is a useful reminder that solar is not a Mediterranean-only technology. Italy simply sits higher on the same curve, with a gentler winter dip.

The number that matters more than production

Here is the counter-intuitive part. Winter is your system's worst season for output and its best season for value per kilowatt-hour.

That is because self-consumption rates run around 80 to 95% in winter^[5], when you are at home with the lights and the heating on and there is very little surplus to spare. In summer they fall to something like 40 to 60%^[6], because you are producing far more than the house can absorb in the middle of the day.

Why does that matter? Because a kilowatt-hour you use yourself saves you the full retail price of electricity, whereas one you export earns you the export rate, which is usually much lower. In the UK, exported power commonly earns around 13 to 15p/kWh under the Smart Export Guarantee, while self-consumed power saves you roughly 25p/kWh^[7]. Every unit you shift from exported to used at home is worth that difference to you.

Seven habits that raise your self-consumption

None of these cost anything. All of them work.

Run the big appliances at midday. Setting the dishwasher, washing machine or tumble dryer on a delay timer for late morning is the single highest-impact change most households can make.
Heat your hot water when the sun is out. If you have an immersion heater or a heat pump cylinder, moving it from an overnight cycle to the middle of the day turns surplus generation into stored heat for free.
Charge the car during the day where you can. An EV charging at home on a sunny weekend afternoon will happily soak up almost everything a domestic system produces.
Pre-cool or pre-heat the house. Running air conditioning or a heat pump a little harder while the sun is up, then coasting through the evening, uses the building itself as a kind of battery.
Stagger, do not stack. Two big appliances running at once will overshoot your output and pull the difference from the grid. Run them back to back instead.
Check your inverter app monthly, not daily. Daily checking makes people anxious in November for no good reason. Monthly totals tell you what you actually need to know.
Do not over-size the system to fix winter. Adding panels to chase December output means paying for capacity that spills onto the grid for eight months of the year. Size for your annual consumption instead.

Where a battery fits, honestly

A battery does not change what you produce. It changes when you can use it, moving midday surplus into the evening. That is genuinely valuable in spring and summer, when there is a real surplus to move. In deep winter there is very often nothing left over to store, which is exactly why battery paybacks are driven by the summer half of the year and by the gap between your import and export rates.

If that gap is small, because you have already found a strong export tariff, a battery earns less. If the gap is large, it earns more. It is worth doing that arithmetic with your own tariff before committing to one.

Seeing your own seasonal curve

All of the figures above are typical values. Your roof's orientation, tilt and shading shift them, sometimes substantially, and a shallow east-west roof will have a different shape to its year than a steep south-facing one.

Whenever you would like to see your own numbers, enter your address and trace your roof with the free Solar Roof Planner. It gives you a realistic estimate of panel count, system size, yearly output, savings and payback for your specific roof. It is free, it takes a couple of minutes, and there is nothing to sign up for.