Do Solar Panels Work in Cloudy or Rainy Weather?
Solar panels still produce power on cloudy and rainy days, just less. How much output drops, how the monsoon affects savings, and why yearly output matters.
"What happens in the monsoon?" is one of the most common worries about rooftop solar. The good news: solar panels keep working on cloudy and rainy days. They produce less, but they do not stop — and over a full year, the sunny months more than make up for the grey ones.
Yes, solar panels work on cloudy days
Solar panels respond to light, not heat. Even when clouds block direct sunlight, diffuse light scattered through the clouds still reaches the panels and generates electricity.
How much output you get depends on how thick the cloud cover is:
| Weather | Approximate output vs a clear day |
|---|---|
| Clear and sunny | 100% |
| Light clouds or haze | 60–80% |
| Overcast | 20–40% |
| Heavy rain, dark clouds | 10–20% |
These are rough ranges. Actual output varies with location, panel type and how quickly clouds pass.
What about rain?
Rainy days reduce output because of the heavy cloud cover, not the water. In fact, rain has a useful side effect: it washes dust off the panels, which can improve output on the clear days that follow.
Quality panels are fully weatherproof, and they are rated to withstand heavy rain and strong winds. A properly installed system with sealed connectors and correct earthing is safe in the monsoon.
Why a few bad days do not ruin your savings
Solar is judged over the year, not a single day.
- Sunny months produce a surplus. In many regions, a large share of the year has strong sunshine, and summer generation is high.
- Net metering balances the year. Depending on your DISCOM's settlement rules, surplus units exported in sunny periods can offset lower generation in cloudy periods.
- System sizing uses annual averages. The common figure of around 4.3 units per kW per day already includes cloudy and rainy days.
So a wet monsoon month lowers that month's savings, but the annual total stays close to what you planned.
Hot sunny days are not always the best days
Panels actually lose some efficiency as they get hotter. A cool, bright, clear day can produce more than a scorching summer afternoon. That is why panel temperature coefficient and airflow under the panels matter. See Types of Solar Panels.
Getting the most from your system in the monsoon
- Check connections before the monsoon. Look for damaged cables, loose connectors and exposed joints.
- Inspect earthing and the lightning arrester, especially important during storms.
- Clean after heavy dust storms that often come before the rains.
- Clear leaves and bird droppings that rain does not remove.
- Keep the inverter protected from rain and dampness.
- Watch drainage around mounting points on flat roofs to prevent waterlogging.
Our maintenance checklist covers a full seasonal routine.
Do solar panels work in winter and fog?
Yes. Winter days are shorter and fog reduces light, so daily output drops. But cool temperatures help panel efficiency, and clear winter afternoons often produce good generation.
Frequently asked questions
How much electricity do solar panels produce on a cloudy day?
Roughly 20–40% of clear-day output under overcast skies, and more under light clouds. The exact figure depends on the thickness of the cloud cover.
Is rooftop solar worth it in areas with a long monsoon?
Usually yes. Annual generation estimates already account for cloudy periods, and net metering balances sunny and cloudy months. A monsoon season lowers savings for a few months, not for the year.
Can heavy rain damage solar panels?
Not quality, properly installed panels. They are sealed and weather-rated. The bigger risks during storms are poor wiring, loose connectors and inadequate earthing, which a good installation avoids.
Do solar panels work during a thunderstorm?
They may generate a little from diffuse light, but output will be low. A lightning arrester and proper earthing protect the system during storms.