How does solar output vary by month?
Solar panels don't produce the same amount every month. Across the UK, a typical south‑facing system produces around 29 kWh per kW in Dec and peaks at about 119 kWh per kW in May.
That's a ratio of about 4.1 to 1 between the highest and lowest months. On average, winter months deliver roughly 46.5% of a typical month. Enter your postcode below to see local numbers.
What the data shows
Summer peaks, winter dips
The summer months of May, June and July consistently deliver the most solar energy, while December and January are the lowest. Even within the UK, there’s a spread: in some western regions winter output holds up better than in the south‑east.
Big differences between regions
In Scotland and Northern Ireland, cloudier skies mean the gap between summer and winter isn't as extreme. In southern England, direct sunlight dominates, so output swings more dramatically between seasons.
What it means for you
At current electricity prices of around 24p/kWh, that seasonal swing is worth knowing in pounds. A typical 4kW system could offset roughly £114 of your bill in May — but only around £28 in December. That gap is why battery storage exists: it lets you bank surplus summer generation rather than export it cheaply, and draw it down when winter output falls short. Oversizing your array or adjusting your tilt angle can also help, but storage gives you the most control. Use the postcode lookup below to see your local monthly figures before deciding.
Typical monthly output (kWh/kWp)
This table shows the average energy yield for a 1 kW south‑facing solar array in each month, averaged across all UK postcodes.
| Month | Average output |
|---|---|
| Jan | 33 kWh |
| Feb | 49 kWh |
| Mar | 82 kWh |
| Apr | 110 kWh |
| May | 119 kWh |
| Jun | 117 kWh |
| Jul | 117 kWh |
| Aug | 105 kWh |
| Sep | 87 kWh |
| Oct | 61 kWh |
| Nov | 40 kWh |
| Dec | 29 kWh |
Check your postcode
Enter your postcode to see month-by-month generation for your area, plus payback and system sizing advice.
How we calculated this
What: Average monthly solar generation per kW in each UK postcode. Shows how output varies across the year.
Data source: PVGIS (Photovoltaic Geographical Information System) typical meteorological year outputs for each postcode centroid, using a 1 kW system facing south at a fixed tilt.
Method: For each postcode we take the monthly PVGIS estimates and compute the mean across all postcodes to derive the UK‑wide averages. Winter ratio is calculated as the average of December–February divided by the annual average monthly yield.
Data sources and citations
Built using PVGIS solar yield estimates from the European Commission Joint Research Centre and UK postcode geography from the Office for National Statistics.
How to cite: SolarByPostcode (2026). Seasonal Solar Output: Typical Monthly Solar Generation in the UK. Retrieved from /insights/seasonal-solar-output/