Do Solar Panels Work in Cloudy or Rainy Weather?
Yes — solar panels work on cloudy and rainy days, they just make less power. Because panels capture diffuse light, not only direct sun, a grey sky reduces output but doesn’t switch it off. And here in Los Angeles — one of the sunniest big cities in the country — it’s rarely the problem people fear.
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- Panels keep producing in clouds and rain — just less, because they capture diffuse light.
- Output is highest on clear days, variable under broken clouds, reduced but nonzero under heavy overcast, and usually low during rain.
- Rain isn’t a plus during the storm — less sunlight reaches the panels — but it does rinse off dust and cool them afterward.
- Annual production estimates from tools like NREL PVWatts already include your area’s cloudy days.
Why panels still work when it’s grey
Sunlight reaches your roof two ways: direct beams from the sun, and diffuse light scattered by the atmosphere and clouds. Solar cells capture both. So on an overcast day, even with no direct sun, the diffuse light coming through the clouds still generates electricity — less than a clear day, but not zero. The thicker and darker the clouds, the lower the output; a bright hazy sky costs you far less than a heavy storm cloud.
How weather changes your output
Pick a sky condition to see roughly how much your panels produce, relative to a clear day. These are directional bars, not exact percentages — real output depends on how thick the clouds are, the time of day, your roof and your equipment.
Output by sky condition
Relative to a clear day (directional).
Illustrative, relative comparison only — illustrative visual levels, not measured output ratios. Actual production for your address is best estimated with NREL PVWatts using your roof orientation, tilt and local weather data.
Does rain hurt your panels?
During the storm itself, production is usually low — not because rain harms the panels, but because heavy clouds block most of the sunlight. There’s an upside, though: rain can reduce soiling by rinsing off dust and pollen, and it cools the modules (panels run slightly more efficiently when cooler — see heat and solar output). So a rainy spell means low output for a day, then often a small boost once the sky clears and the glass is clean.
What about snow and fog?
Snow is a non-issue for almost all of Los Angeles. Where it does occur, a light dusting slides off tilted panels and they resume once the surface clears; deep snow cover stops production until it melts or slides. Fog acts like heavy overcast — reduced but nonzero output that lifts as it burns off, which in coastal LA it usually does by midday.
Cloudy days are already reflected in LA’s annual solar estimate
Los Angeles has one of the strongest solar resources of any major U.S. city — our data puts it near 1,700 kWh a year per kW of panels, cloudy days included. If solar makes economic sense in genuinely cloudy places like Germany (which built a world-leading solar market on far less sun), an occasional grey LA morning isn’t going to break the math. See how much sun LA really gets.
What this means for an LA homeowner
Weather is already in the estimate
A proper production estimate runs your address through NREL-based weather data, so your local cloudy days are already counted. If a proposal’s output looks unusually high or low, check its shading, orientation, equipment and modeling assumptions. Local cloud patterns should already be included in the weather dataset.
Don’t oversize for clouds
LA’s resource is strong and consistent; you don’t need extra panels to hedge against grey days. Size to your usage — see how many panels you need.
Nighttime is the real gap
Clouds cut output modestly; night stops it entirely. If you want power after dark, that’s a battery decision — see do solar panels work at night.
Sources & methodology
Primary and authoritative sources for this page: NREL — PVWatts Calculator (includes local weather) · NREL — National Solar Radiation Database · DOE — How does solar work?. Figures and program statuses are current as of publication — verify time-sensitive items (rates, tariffs, incentive budgets) on the official source before relying on them.
Frequently asked
Do solar panels work on cloudy days?
Yes — they produce less, but they keep working. Solar cells capture diffuse light scattered through clouds, not just direct sun, so an overcast day still generates electricity. Output is highest on clear days, variable under broken clouds, and reduced but nonzero under heavy overcast.
Do solar panels work in the rain?
They keep working, but output is usually low while it’s raining — because heavy clouds block most of the sunlight, not because water harms the panels. Afterward, rain can actually help: it rinses off dust and pollen and cools the modules, which can slightly improve output once the sky clears.
How much does cloud cover reduce solar output?
It varies a lot with how thick and dark the clouds are, the time of day, and your system — which is why a single universal percentage is misleading. Directionally: clear skies give the highest output, broken clouds are variable, heavy overcast is well below clear but still productive, and rain is usually low. Your annual estimate from NREL PVWatts already accounts for your area’s cloudy days.
Is solar worth it if it’s sometimes cloudy?
In Los Angeles, absolutely — it’s one of the sunniest major U.S. cities, with a strong, consistent solar resource. Even genuinely cloudy regions like Germany built large rooftop-solar markets, so occasional grey LA days don’t change the economics. What decides it is your electricity rate and your roof, not the odd cloudy morning.
Do I need more panels because of cloudy weather?
No. LA’s solar resource is strong and consistent, and any credible production estimate already bakes in local cloud cover using NREL weather data. Size your system to your usage rather than padding it against clouds. See how many panels you need.
Related reading
Sunny LA, real numbers
Get a production estimate modeled on your exact roof and local weather from a licensed local installer — clouds already included.
Get a free estimatePrepared by Cali Energy, July 2026. This article is for general educational purposes only and is not legal, tax, financial, engineering, or utility advice. Rates, incentives, codes, permit requirements, equipment specifications, prices, and program terms may change; figures and timelines are estimates, not guarantees. Confirm current requirements with the applicable utility, AHJ, program administrator, manufacturer, or a licensed professional. See our Content Disclaimer. Cali Energy · 19201 Parthenia St Unit E, Northridge, CA 91324 · CSLB #1032379 (B, C-10, C-39)