Yes, they absolutely do!
A sudden cloud cover often causes homeowners to panic about their system’s health because of the lingering idea that solar is only for bright, sunny days.
Reduced generation under cloud cover can quickly look like your solar panels aren’t working, when it’s simply a normal daylight response.
If the sun isn’t blazing, how could solar possibly keep working?
Modern solar panels generate power from diffuse light, the kind that passes through clouds, rain, and haze. While your system’s output will naturally dip during heavier cloud cover, your panels don’t simply “switch off” just because the weather turns. That matters in a city like Sydney, where conditions can change in an instant.
Yes, Solar Panels Capture Energy in Overcast Conditions
Solar panels are built to work with all available daylight, including the softer light present on cloudy or rainy days. Solar panels don’t rely on harsh, blazing sun alone. They’re built to work with all available daylight, including the softer light present on cloudy or rainy days.
As long as visible light is present, even on cool, cloudy days, that process continues. This is why solar panels can still perform efficiently in milder conditions and why temperature alone doesn’t determine output.
| Type of Light | What It Is | How it Affects Panels |
| Diffuse sunlight | unobstructed sunlight hitting the panels | produces maximum output on clear days |
| Diffuse light | sunlight scattered by clouds | still generates electricity, just at a lower level |
Solar panels produce very little power once daylight fades but…
Once a solar installation team installs the solar system, you might notice a small power bump on full-moon nights or a slight output triggered by a nearby streetlight. Unfortunately, these weak, diffuse light sources cannot generate enough energy to power your home.
Technically, moonlight is just sunlight reflecting off the moon’s surface.
While an artificial light within the panel’s spectral response range can provide enough photons to trigger electricity production, the process remains highly inefficient. You will find that these light sources are rarely worth harvesting for your household needs.
Why Not All Cloudy Days Affect Solar Panels the Same Way
When you look up and see wispy, high-altitude clouds, you can rest easy knowing your solar production remains steady and largely undisturbed.
If the sky shifts to standard overcast conditions, you should expect a roughly 50% dip in your energy generation as the cloud cover thickens.
However, the most significant impact occurs during heavy, low-hanging dark clouds, where your system’s output takes a major hit and can drop by 70% to 90%.
However, cloud cover isn’t something you can precisely measure
While researchers grouped clouds into broad categories, high, medium, and low altitude, they couldn’t consistently measure how thick those clouds were or how much sunlight they blocked at any given moment. Cloud density, movement, and layering change too quickly, making real-time accuracy difficult even with structured classifications.
A research paper from Tomas Bata University in Zlín, Czech Republic, highlights a key limitation in predicting solar output under cloudy skies. The study examined how cloudiness affects electricity generation from photovoltaic systems and found that pinpointing the exact impact of specific cloud types isn’t realistically possible.
The “Cloudy Day” System Health Checklist
When the clouds roll in, you want to make sure your panels are absorbing every possible bit of light. You can keep your system running at its highest potential during grey weather by ticking off these simple health checks:
- See nearby branches cast; light is already limited on cloudy days, any extra shading can cause your output to drop significantly further
- Check for stubborn grime that might block the weak, diffuse photons trying to reach your cells
- Gutters and the area under your panels should be clear of leaves to prevent water from splashing back onto the electrical
- Check if your system hasn’t “tripped” during a lightning storm or heavy downpour. Monitor your inverter for any fault lights or error codes
- Use your app to verify that your output matches the expected rates for specific cloud levels
- Look for signs of pests under the panels, as they seek dry shelter during rainy days and can damage the wiring
Solar Batteries – The Path to Weather-Independent Energy
Cloudy days are a natural part of the local weather cycle, but they do not result in a total loss of energy independence. You can move away from worrying about the daily forecast by adopting a “set and forget” energy strategy for your home.
A professional assessment determines if your panels are angled correctly to capture the best possible light when your output falls below city averages.
Adding a solar battery serves as the most effective way to manage a rainy week because it banks the excess power you generated during previous sunny periods.
FAQs
Yes, solar panels continue producing electricity using diffuse sunlight that passes through clouds, though at reduced output.
Light cloud cover may cause only a small dip, while heavy, dark clouds can reduce output by 70%–90%.
Yes, rain does not stop solar generation as long as daylight is present, and rain can even help clean dust off panels.
No, solar panels often perform better in cooler temperatures since excessive heat can reduce efficiency.
Cloud thickness, altitude, and movement vary constantly, which changes how much sunlight reaches the panels.
No, moonlight and artificial lights are far too weak to produce usable energy for household needs.
Yes, fluctuations are expected and usually reflect changing cloud density rather than a system fault.
Check your inverter or monitoring app to ensure output aligns with typical cloudy-day performance levels.
Yes, even small amounts of shade can significantly reduce output when available light is already limited.
Absolutely—solar batteries store excess energy from sunny days, allowing you to use that power when production drops.
