A common question before buying: is a solar system worth it at all in winter? The clear answer is yes. In Switzerland, about 25 to 30 percent of annual production falls in the winter months from October to March. For a typical 10 kWp system that is still 2,000 to 3,000 kWh. How much your site delivers specifically can be estimated in advance — best via a free quote with a site-specific yield forecast.
Why the winter yield is lower
Several factors reduce production in winter:
- Shorter days: in December the sun shines only around 8 hours, compared with 16 in June.
- Low sun: in winter the sun rises only 20 to 25 degrees above the horizon.
- More cloud cover: especially on the Central Plateau, fog and overcast skies reduce irradiation.
- Snow cover: it covers the modules only temporarily, usually for a few days.
Cold increases efficiency
What many don't know: solar modules work more efficiently in the cold. For every degree below 25 °C the efficiency rises by about 0.4 to 0.5 percent. On a clear winter day at −5 °C your system therefore produces more electricity than on a hot summer day with the same irradiation. An 8 kWp system in the Zurich area delivers on average around 280 kWh in December, about 350 kWh in January and already over 500 kWh in February.
Snow on the modules: what to do?
The worry about snow is mostly unfounded:
- Self-cleaning: from about 30 degrees of pitch, snow slides off by itself.
- Dark, smooth surface: modules warm up and thaw snow faster than roof tiles.
- Frameless modules: snow slides off even more easily here.
If clearing is nevertheless needed: use only soft brushes or squeegees with a rubber lip, never sharp objects — and for safety reasons do not climb onto the roof when it is icy. In most cases, waiting is the best solution.
Optimisation for maximum winter yield
- Tilt angle: for year-round yield, 30 to 35 degrees are ideal; for maximum winter yield, 45 to 60 degrees.
- Bifacial modules: they use reflected light — with snow, the reflection can significantly increase the yield.
- Façade modules: vertical modules on the south façade have a better angle of incidence in winter and stay free of snow.
- Location: sites above 800 m often benefit from less fog and more hours of sunshine.
Monthly yields over the year
| Month | Yield (10 kWp) | % of the year |
|---|---|---|
| January | 350–450 kWh | 3.5–4.5% |
| February | 500–650 kWh | 5–6.5% |
| March | 800–1,000 kWh | 8–10% |
| June | 1,300–1,500 kWh | 13–15% |
| October | 600–800 kWh | 6–8% |
| December | 250–350 kWh | 2.5–3.5% |
Using winter electricity cleverly
Since less solar electricity is available in winter, efficient use matters: run large appliances during the day, schedule the heat pump around midday, size the battery storage sensibly and, where applicable, check "cloud" tariffs to retrieve summer surpluses in winter.
Conclusion
Even with reduced winter operation, a solar system remains a worthwhile investment — the annual return of 5 to 8 percent is barely diminished. All yield values are averages; a precise forecast for your site is produced by specialist firms via simulation. Request a free quote for this, or calculate it yourself with the solar calculator.
