The myth of “not enough sun”
A common confusion is to judge solar on a few gray days. A photovoltaic project is designed over 12 months, not over a week in winter. In Switzerland, the combination of seasons makes annual production sufficient to achieve solid profitability levels.
What really changes in overcast weather
When the sky is cloudy, direct irradiation decreases but a diffuse part remains exploitable. Instantaneous power decreases, however production does not stop. This is why monitoring over the entire year is essential to interpret performance correctly.
Levers that improve results
Three elements have more impact than the weather on a specific day: the quality of installation (orientation and shading), the choice of the inverter and the self-consumption strategy. In practice, a well-installed system in a French-speaking canton remains efficient even with prolonged cloudy periods.
Practical conclusion
The right reflex is not to ask “is there enough sun this week?” but “what realistic annual production for my roof?”. This approach allows to avoid sizing errors and unrealistic expectations.