Find Out if and How Solar Panels Work on a Cloudy Day
Solar panels can still generate electricity on overcast days, but their effectiveness is reduced compared to sunny days. Here are the key factors and considerations regarding solar panel performance on overcast days:
I can show you. I have a 12,500 watt system set up and you can see what happens to the daily output on cloudy days. If it is a dark snowy winter day, the output is near ZERO. On days that are better, you get maybe half output. Panels do not work worth a crap on very cloudy days. Also included is one day that had clouds and sun so you can see what happens to output when it is a relatively clear day with clouds.
first, a nice clear day:
Here is a day that was mixed clouds and sun:
Here is a month of mostly clear with some clouds:
Here is a nice winter month: The dead zone is from a winter storm of dark grey days.
And here is a nice summer month:
So panels sort of work when there are clouds but they work best with clear skies.
1. Reduced Efficiency
- Light Diffusion: Clouds diffuse sunlight, reducing the intensity of light reaching the solar panels. On a heavily overcast day, solar panels may produce only 10-25% of their rated capacity.
- Performance: On partly cloudy days, panels might generate between 30-50% of their typical output.
2. Types of Solar Panels
- Monocrystalline Panels: These panels are generally more efficient and perform better under low-light conditions compared to other types.
- Polycrystalline Panels: Slightly less efficient than monocrystalline panels, but still capable of generating electricity on overcast days.
- Thin-Film Panels: These can perform better in low-light conditions compared to traditional silicon panels, but they typically have a lower overall efficiency.
3. Location and Climate
- Geographical Variability: Locations with frequent overcast weather, like the Pacific Northwest in the United States, still find solar panels viable due to the annual energy yield rather than daily peaks.
- Seasonal Variation: Solar panels can accumulate enough energy during sunnier seasons to offset periods of lower generation.
4. System Design and Optimization
- Angle and Orientation: Optimizing the tilt and orientation of solar panels can maximize energy capture, even on cloudy days.
- Microinverters: Using microinverters instead of a single central inverter can help maximize energy harvest from each panel, especially when some panels are shaded or receiving less light.
- Energy Storage: Batteries can store excess energy generated during sunny periods for use during cloudy days or at night.
5. Technological Advancements
- Bifacial Panels: These can capture light from both the front and back sides, potentially increasing efficiency on overcast days by reflecting light from the ground.
- Advanced Coatings and Materials: Innovations in solar cell technology aim to improve performance in diffuse light conditions.