How Do Solar Panels Work in Shade, Cold Or Bad Weather
Equipping one’s property with solar power is a great idea. But it’s not at all a small investment. A common misconception about solar panels is that they work really well in hot regions and probably don’t deliver in snow, shade and rain. And that’s not exactly true. There are two components of solar energy- heat and light. and the PV system needs only light energy to make solar power. So we don’t always need clear skies. For maximum efficiency, yes, direct sunlight is necessary but even when the weather is not perfect today’s solar panels can collect
enough light to produce electricity.
We don’t get the same amount of sunlight throughout the year everywhere in the world; so the curiosity regarding the efficiency of solar panels in regions that don’t get enough sun is quite valid. One might start to think, are roof-top solar panels even worth their price when the roof is frozen with snow half the time? The answer is- solar panels harness radiant light of the sun to produce solar power, not its heat, so it doesn’t matter if it snows. As long as there is light, your solar panels are going to work just fine. Rather they would perform better in clear and
colder weather than they would in peak summers. We will now find out why.
– How temperature affects the efficiency of solar panels:
To learn how solar energy works in cold, rainy and gloomy weather we need to find out how change in temperature affects their working. One might think more heat means more solar power but the truth is solar panels work best between 15°C to 35°C and are tested at standard testing conditions (STC) of 25°C. They are robust by design and require low maintenance and they can withstand extreme weather both hot and cold. Solar panels can get as hot as 65°C in warmer regions of the world during peak summers depending on a few other factors like the amount of sunlight, air temperature, material used in roofing etc. In case of such weather, even when there is enough sun, the efficiency of solar panels drops by a little because the voltage of a PV cell decreases with increase in temperature.
So they are made to withstand all kinds of weather be it snowy, rainy or sunny. And their efficiency doesn’t suffer as much as you would think, as even visible light is enough to produce some amount of electricity.
– Understanding the temperature coefficient:
Now that we have learnt that beyond one point(25°C STC) the efficiency of solar panels drops with increase in their temperature, let us find out by how much does it drop and why does it happen. Everyone who plans to get their homes equipped with solar power gets this piece of advice from someone- “don’t forget to look at the spec sheets”. And when they do, they can check out the temperature coefficient of various solar panels there. The temperature coefficient helps us understand by how much the efficiency of the panels will drop per degree
Celsius/Fahrenheit. For instance, the temperature coefficient of monocrystalline solar cells is around -0.5%/°C, which means every time the surface temperature of the mono solar panels goes above 25°C by 1°C they generate 0.5% less power than the optimal.
One can easily infer from this that solar panels are more efficient in colder weather. But again, during the warmer days due to early sunrise and late sunsets we get more sunlight and for longer duration. Hence the solar panels gather light for more time and make up for the small compromise in efficiency caused by the rise in surface temperature of the panels. So there is not a huge difference in overall electricity produced based on just the temperature of seasons.
– Solar Power In Shade:
There are parts of India that see some of the highest rainfall in the world and it pours there more months around the year than it doesn’t. Cloudy weather can too affect the efficiency of solar power production. It is estimated that solar panels are 40% less efficient in peak cloudy weather. If it’s not completely dark and the sun is still hiding in the clouds the solar panels will still gather enough solar radiation to produce some electricity. Solutions like roof orientation and right design of solar panels can help minimize the compromise in solar power caused due to
bad weather. To assume that there won’t be any solar energy without direct sunlight is wrong. Modern panels are capable of producing enough solar power even in low light conditions.
Same goes for shade caused by trees and buildings surrounding the roof-top. We already discussed that we don’t need heat from the sun to generate solar energy. It then depends on how much surface area of the solar panels is covered in shade. If half of the PV panel is covered in shade and the rest of it sees clear sunlight, only the cells that lie in shade will be slightly less efficient while the others will run on their best.