Will solar panels work on cloudy days?
Solar panels do still work on cloudy days as the UV penetration through the clouds will still allow for some generation. However, production will be much lower than a bright sunny day. The decrease in production will depend on many variables as explained throughout this article.
When you look at a graph of solar production over the course of a day, it is very rarely a solid line of solar production without ups and downs. There are exceptions to this where the sun is out all day with zero cloud cover and a nice breeze, which allows solar production to be consistent without drops due to clouds or panels getting too hot.
For how solar panels work in hot temperatures check out this article.
The chart below shows a rare day where the solar production curve is almost perfect! The weather on this day was clear blue skies, in the winter so the panels did not get too hot!
So, can solar still work on cloudy days?
When we compare the chart above to a partly cloudy day, you can see all the interruptions in the production line due to cloud cover:
As a further comparison, the chart below shows a very cloudy day:
What happens to solar panels on a cloudy day?
Solar panels work when UV from the sun hits a silicon wafer beneath the glass of the solar panel. This makes electrons move which is what generates electricity for your home or business. When cloud covers the sun, the UV penetration drops significantly which results in much lower solar production.
A good way to think about this is: imagine when you are out in the sun… if you don’t have sunscreen on you will likely get burned if you stay outside for too long. If you are out in the sun for the same amount of time but there is thin cloud cover, you are likely to get burned less. If the cloud cover is thicker, then the protection will be higher, and you will burn less again. The cloud cover basically provides a layer of protection from UV but does not stop it getting through altogether. Your solar panel will still get some UV in the same way your skin does, but the cloud will lessen its effects.
Will my solar panels generate electricity during cloudy or rainy days?
As mentioned above you will still generate electricity on cloudy days, but the amount of energy will be lower. Rainy days will have the same impact. On some really wet days your solar production may be as low as 10% compared to a sunny day.
Which solar panels work best in cloudy conditions?
Essentially, cloud cover and shade is bad for solar. There are no solar panels that completely eradicate the losses due to shading or cloud cover. Using Microinverters or power optimisers will help increase the tolerance to partial cloud cover and shade but once again it is not a complete solution, just an improvement.
In terms of which solar panels will cope best with cloud cover, thin film modules are best suited for really cloudy conditions. However, thin film are less efficient in direct sunlight which makes them more suitable for European climates where they have longer winters and more cloudy days than Australia.
In Australia we are blessed with a fantastic climate for solar production so using a monocrystalline or polycrystalline (also known as multicrystalline) solar panel is by far the best choice right now! There is a lot of money being poured into research and development in solar technology to improve tolerance to cloud cover and shade so small improvements are made with every new model that arrives.
As the situation stands, we get amazing results from solar here in Australia, as illustrated in the charts below!
Solar panels are not immune to cloud cover or any type of shading. However, we get more solar yield here in Australia than nearly anywhere else in the world. You basically have to take the rough with the smooth and accept that some days your solar production will be quite low. When you average it out though, solar in Australia is still red hot!
For some useful tips, check out these links: