Before purchasing our home-power system, I did quite a bit of reading on panels and snow. Why? Because where I live it snows… like a lot!
And between the articles that I could find and a few emails from different salesman, the general opinion that I was left with was that snow wasn’t going to be much of a problem.
That could not have been more wrong!!!
Let me give you an example.
I have a solar array rated at 7.8kW (7800 watts). In the winter time, if there is snow on my panels, it is not unusual to find that my array is only producing .2 kW (200 watts). So while the panels are technically working, they are clearly not working very well.
Take it from someone who lives off-grid, solar panels will not work if covered with as little as an inch of wet snow.
Photovoltaics require direct sunlight. Consequently, the more interference between the sun and your panels, the less your panels will produce. And this interference can include, not only the snow laying on your panels, but the tiny ice crystals that sometimes seem to hover in the air, as well as, the clouds that delivered them.
Different Types Of Snow
Snow and solar panels do not produce the same negative result in every situation. Here are a few examples of different kinds of snow and how they can effect your power production.
- Fluffy Snow – Snow that can be blown by the wind – If you were get 2 inches of light fluffy snow, then it’s reasonable to assume that a few hours of good sunlight could easily clear your panels. This snow tends to be very airy and is the least detrimental to your power production.
- Wet Snow – Great for making snowballs! – As wet snow has such a high moisture content, this means it possesses more ‘interference’ for the sunlight to travel through. So while this snow is great for making snowmen, it’s not so good for power production. Fortunately, wet snow tends to slide under its own weight and will quite often, clear itself from your array.
- Compact Snow – The kind that seems to really want to stick to things – Compact snow is no friend to solar power. Even in smaller amounts, it can be quite detrimental to power production. I have experienced instances where my panels had Frisbee sized bare spots (with no snow at all) and yet, because of the compact snow covering the rest of the panel, my home power system failed to really produce.
Location, Location, Location
One might think that the different types of snow would be the only variable in the loss of power production from your panels. But there is another factor in this equation – your location.
For example, if you were to get a wet snow in an area that typically has dry air (say, a higher altitude), then it is most likely that the panels would quickly clear themselves and be back to producing power in short order.
In comparison, if you were to get a wet snow in the the Great Lakes region, especially in early winter when lake water is still shedding its stored summer heat, then the time it would take to get back to full power production might be considerable.
Remember, photovoltaics require direct sunlight. And any moisture content that is in the air will directly impact how well your panels are able to perform.
Tools To Help
Understanding the atmospheric elements relative to your area will go a long ways in helping you size your array.
A home in the desert will require less panels than a home in the aforementioned Great Lakes area as there will be less to interfere with the sunlight as it makes its way to your panels.
In the same token, a home close to the equator will provide more in the way of consistent sunlight hours than a home in extreme northern or southern latitudes as daylight hours can significantly shorten with the tilting of the planet.
A good tool to help you understand what you can expect for sunlight over the course of a year can be found at https://www.suncalc.org/