How do solar panels perform in cold climates?
Sunny climates are best for solar panels, of course - but sunny and cold is actually better than sunny and hot.
If you ask someone to think of a place with a sunny climate, most people will think of somewhere sunny and warm, like Florida or Arizona.
Solar panels like sun, of course. The amount of electricity that panels generate is in direct proportion to the amount of light they receive. However, while sunny weather is great, hot weather isn’t. In fact, the best conditions for generating solar electricity and sunny and cold.
This might be a little counterintuitive because sunny cities tend to also be warm, but you can observe this yourself if you’re currently a solar homeowner. If you check your monitoring system, you may find that cool and clear spring days generate more electricity for you than summer days, even though summer days are longer.
All of this means that solar electricity can work for you, even if you live in a northern climate or - as you can see in the photo above - Antarctica!
Why do solar panels perform better in the cold?
The electrical resistance within a solar cell increases as the temperature gets hotter. Higher electrical resistance means that electrons aren’t able to move as freely, and some of the electrical energy gets converted to heat and is wasted.
When it comes to solar panels, this is a well known phenomenon. In fact, if you look up the specification sheet for a solar panel, you should find the power temperature coefficient listed.
This figure will be listed as a percentage loss of efficiency for every one degree Celsius increase in temperature. For example, a power temperature coefficient of -0.26%/°C means that for every 1°C increase in temperature, the solar panel will generate 0.26% less electricity.
-0.26%/°C happens to be the rating for a REC Alpha Pure-R series, which currently has the best power temperature coefficient of any panel I’ve found. Many other high quality panels will be in a similar range. Once you’re looking at cheaper budget panels, the power temperature coefficient will be measurably worse: somewhere in the range of -0.45%/°C.
I explain all of this because the power temperature coefficient shows how the efficiency of a panel increases as it gets colder. So while our REC Alpha panel will lose 0.26% efficiency for every one degree increase in temperature, it will become more efficient by the same amount as it gets colder.
This is a bit of a deeper topic, so you can read the article linked above to learn more about power temperature coefficient.
Daylight hours are actually about the same everywhere
One thing to know about sunlight on planet Earth is that everywhere gets approximately the same number of daylight hours annually. For example, the polar regions experience winter days with no sunlight at all, and summer days with 24 hours of daylight.
The position of the sun in the sky varies, though. At the equator, the sun on average will be high above, while at the poles the sun will tend to be near the horizon. That’s why the solar panels in the Antarctica station pictured above are mounted nearly vertical. That orientation will let them capture more sunlight from the sun as its low in the sky.
Annual daylight hours might be similar everywhere, climate isn’t
While the hours of daylight might be approximately the same everywhere on earth, the intensity of that sunlight isn’t.
This is because climate isn’t the same everywhere. For example, the cities in the southwestern United States have a much drier climate than those at a similar latitude on the east coast. Because of this, the average city in southern California will have more sunshine on average than cities in South Carolina, even though they are at similar latitudes.
Still, you will find that cold cities can be surprisingly good for solar power generation. To find this out, you can use the Solar Nerd calculator or software called PVWatts (which is what the Solar Nerd uses behind the scenes).
As a test, I used PVWatts to calculate the power generation for a 4 kilowatt solar array in two cities: Anchorage, Alaska and Jacksonville, Florida.
Because both cities are at very different latitudes, I used a different tilt for each system. A system in Anchorage needs a much higher tilt because the sun is lower is the sky throughout the year.
Surprisingly, the same system in Anchorage can generate about 70% as much electricity annually as one located in the Sunshine State. Here’s a summary of the data for our theoretical 4 kW solar array:
|City||Tilt||Estimated annual power generation (4 kW system)|
|Anchorage, AK||40°||4,124 kWh|
|Jacksonville, FL||25°||5,878 kWh|
The Anchorage system generates less electricity than one in Jacksonville, as you would expect. However, 70% is still pretty good, and perhaps more than most people would guess.
If you live in a colder climate, there are solar resource maps that show you how much sunshine you can expect in an average year.
Bottom line: solar does work in colder cities, but expect less output
Solar panels located in colder climates tend to generate less electricity, but not because of the cold. In fact, cold solar panels are better at generating electricity than hot ones.
The reason that cold climates tend to be worse for solar is because the climate is usually less sunny. That said, solar panels can be viable anywhere - even a science station in Antarctica.
I should also mention that my solar home in located in Buffalo, which is better known for snowstorms that dump 5 feet of snow than it is for solar power. Despite that snowy reputation, my neighbors and I have been very satisfied with our home solar.