Do Solar Panels Work in Winter?

Why Winter Output Is Lower (But Still Valuable)

Three factors reduce winter generation: fewer daylight hours (roughly 8 hours in December vs. 16 in June), a lower sun angle meaning less direct irradiance per square metre, and more frequent cloud cover. Combined, a typical December produces around 18-20% of what June generates.

However, this is not the full picture. Winter is when electricity is most expensive, and when you are most likely to be at home using power. Every kWh your panels generate in winter directly offsets a kWh you would have bought from the grid at peak rates.

How Battery Storage Changes Winter Economics

Without a battery, winter solar generation often coincides with periods when nobody is home to use it. The power gets exported at the SEG rate (~10.8p/kWh) rather than offsetting grid imports at 29p/kWh.

A battery changes this equation significantly. Even the modest 100-200 kWh generated on a December day can be stored and used during the 4-7pm peak demand window. Combined with off-peak charging overnight (if you have a time-of-use tariff), a battery can slash winter bills too.

Cold Weather Actually Helps Efficiency

Solar panels are electronic devices, and like all electronics, they perform better when cool. Panel efficiency drops by approximately 0.3-0.5% for every degree above 25 degrees C. On a crisp, clear winter day, panels can actually operate at above their rated efficiency — partially compensating for the reduced daylight hours.

Snow rarely causes issues in Wiltshire. Our maritime climate means snow accumulations are light and short-lived. Panels are typically mounted at angles of 30-40 degrees, so snow slides off within hours. The dark surface of panels also absorbs heat, accelerating snow melt.