How Much Energy Do Solar Panels Produce on Cloudy Days?

One of the most frequent questions we hear from future solar users is: Do solar panels work when the sky is cloudy? At RenovaEnergy, we explain how cloud cover affects solar performance and why solar power is still efficient even without direct sunlight.

Do solar panels work on cloudy days?

Yes. While their output is lower, solar panels continue generating electricity thanks to diffused sunlight—light that passes through the clouds.

How much does production decrease?

The loss of performance depends on how dense the clouds are. In general:

• Lightly cloudy: 60% to 80% of normal production
• Moderately overcast: 30% to 50% of normal output
• Very cloudy or rainy: 10% to 25%, but rarely zero

Do all panels perform the same in cloudy weather?

No. Some panels, such as monocrystalline models, are more efficient in low-light conditions. The inverter and monitoring systems also play a key role in maximizing performance.

How does this affect savings?

If you live in an area with frequent cloudy days, your annual production might drop slightly. But in most parts of Spain, the impact is minimal and annual output remains high enough to ensure profitability.

What if I have a solar battery?

Batteries help stabilize your energy use. You can store excess electricity from sunny days and use it when production drops due to weather.

Bottom line? Clouds aren’t a problem

Solar panels don’t need direct sun to work. While performance may decrease on cloudy days, they still generate valuable electricity. A properly designed system will account for this and ensure reliable output year-round.

Curious if your location is a good fit for solar? RenovaEnergy will assess your site, consumption habits, and sun exposure to give you a clear answer.