As I am sure we all can agree, no matter what, there is some sunlight even on the worst of days. Sunburns can even happen on a day when you don’t see the sun break through the clouds at all. That being said, can solar still generate power in bad weather? The simple answer is yes, but let’s expands on that.
A huge myth is that solar panels do not generate power on cloudy days. They do; however, it is only about 10-25% of their rated capacity. The variation depends on the density of the cloud coverage and other weather factors. Since the UV rays still come through, development of solar panels that can use this to generate power is currently in development.
Cooler temperatures also affect the power generated from solar panels. Solar panels are much more efficient in cooler temperatures than in hot areas. A study has shown that solar panels in San Francisco CA generate similar power to Sacramento CA. This is due to the cooler temperatures of San Francisco compared to the heat in Sacramento.
Fog has also been shown to produce better power generation due to the fact that the fog allows the sun to hit the solar at an obtuse angle and allows more sunlight to reach the panels. This may seem counterintuitive from what you would think, but it is definitely good news for areas with overcast weather or colder climates.
Take Germany for example. The country as a whole has installed 35 gigawatts of solar, yet most of the country is overcast and cold. This hasn’t slowed down the installations at all and they even plan to hit 52 gigawatts in the near future. UK is even working to catch up to the solar installations of Germany and it will be interesting to see how this progresses.
With off grid solar systems, such as our solar lighting systems, using worst case scenarios is the best way to ensure that your solar system is still able to produce enough power to sustain during times of inclement weather. This is done by looking at the winter insolation available along with providing plenty of autonomy for the battery backup system.
Grid tied systems are a little more forgiving since they are feeding the grid during the day and then using the grid power during the nighttime. These systems are not relying on the battery backup to provide the power during nighttime hours, so fluctuations in power generation isn’t a huge concern.
So yes, both off grid and grid tied solar systems will produce power even in some of the worst conditions. Knowing the requirement differences between the two systems will help you determine if the systems are sized correctly to ensure that no matter what the weather is, power will still be generated always helping keep the lights on.