Do Solar PV Panels Work In Cold Weather Conditions?

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Solar panels are powered by the sun. The Pope also lives in the Vatican, and water is indeed wet. Knowing this, it would be easy to figure that solar panels do their best work on a hot sunny summer’s day, while basically sitting idle on a chilly winter’s afternoon.

But how valid is this? What’s the science behind solar panel efficiency, and is this preconception true? After all, surely buying solar panels in a country where winter seems almost perpetual is just asking to lose your money.

Let’s take a look at how solar panels work, and if a cold dreary day is going to damage your solar output enough to render a solar panel "not worth it".

How do solar panels work?

We won’t mince words here – the science behind solar panels is complicated and confusing for those of us who aren’t engineers. So we’re going to do our best to make it as simple as possible, for your sake and ours.

So the sun emits heat and light – this much we all know. And light, you may also know, is made up of tiny particles called photons. Meanwhile, every solar panel is essentially a magnetized sandwich, with each slice of "bread" being packed with atoms. When these photons hit a solar panel, the design of the panel causes the photons to knock electrons off of these atoms. This generates an electric current, which then powers your house or gets stored in a battery.


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If a solar panel needs sunlight, surely they do their best work in summer?

That’s where it gets a little tricky. No one could blame you for thinking that a solar panel does its best work on a hot summer’s day. However, seeing how complicated these devices are, you can assume they're pretty capable of functioning in different types of weather.

Part of this is true. Solar panels (obviously) need the sun to operate; the more sun that shines down onto the panel, the more efficient it will be at producing energy. That much is easy to figure out.

The surprising part is that solar panels are actually less efficient in intense heat. Yes, we know – a device that operates best in direct sunlight is impeded by high temperatures. It’s certainly a bit of a design flaw – perhaps an obstacle for future solar panel generations.

It doesn’t take much heat to start lowering a panel’s efficiency. In fact, all solar panels have a “Pmax temperature coefficient.” This refers to the amount of power a solar panel will lose as the temperature rises 1°C above 25°C.

We’ve found Pmax numbers for some of the bigger solar panel models and listed them here.

Model
Pmax Coefficient (%/°C)
Sunpower Maxeon 3
-0.29
Panasonic N330
-0.26
LG NeON 2
-0.37
Canadian Solar HiKu
-0.37
TrinaSolar Duomax
-0.39

Information updated in July 2019.

As you can see, a solar panel in 26-27°C won’t have a noticeable drop in output – but in a place like Nevada or Egypt, the sweltering heat would reduce a panel’s efficiency by a considerable amount.


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So solar panels actually work best in winter?

There are a lot of different environmental influences on solar panels, and they all kind of conflict with each other. For example, solar panels rely on the sun, but don’t function well in high temperatures. Rain helps to clean dust and dirt off of the panels, but would obviously come with grey skies.

A common misconception is that solar panels stop working on cloudy days. While it’s true that clouds certainly impede peak conversion, plenty of sunlight still penetrates the clouds. After all, when clouds coat the sky, it’s not like we’re all stumbling around in darkness – it’s very much still bright. That means your solar panels will still be getting suitably juiced up throughout the day.

Heat is another surprising factor. As we mentioned, solar panel efficiency is significantly impeded by heat. This means a nice frosty winter morning after a night of light rain is the perfect time for a solar panel to do its job.

This is exactly why American cities like Boston and Portland, despite having long cloudy seasons, are rapidly climbing the ranks in terms of solar power. The falling costs and rising efficiencies of solar panels mean that installing panels in cloudier areas is more feasible than ever before.


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What about snow?

Even though we don’t get blizzards upon squalls in the UK, snow can still rear its head when you least expect it, in months as late as April. The thing is, snow is the worst possible environment for solar panels. It can cover the panel entirely, meaning no light gets through, and if enough snow piles up, it can break the panel altogether.

To make sure you know what kind of chilly punishment a solar panel can take, we’ve taken some of the bigger solar panel brands and had a look at how much snow their top models claim to be able to handle.

Model
Snow load (Pascals)
Sunpower Maxeon 3
6,000 Pa
Panasonic (All models)
5,400 Pa
LG NeON 2
6,000 Pa
Canadian Solar HiKu
5,400 Pa
TrinaSolar Duomax
5,400 Pa

Information updated in July 2019.

Firstly, if the unit “pascal” means nothing to you, then you should know that one pascal is equal to one newton per square meter. And if you don’t remember your Year 7 science lessons, a newton is the amount of force needed to accelerate a one kilogram mass at the rate of one metre per second squared.

1 Pa is approximately 0.1 kg/m². This means that panels with a 6,000 Pa load can handle 611.8kg/m² of snow before something goes wrong. Panels with a 5,400 Pa maximum can take 550.6kg/m². As you can see, this is a lot of snow – more than we’re ever likely to get over the course of one night. Even if we do experience a cold snap, it won’t be hard to brush some snow off every day to minimize the risk of damage to your panels.


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All in all

Solar panels are full of contradictions, where any benefit is coupled with a disadvantage. In a strange way, autumn-winter is the best time period for solar panels. Despite the fact that the days are shorter (exposing the panels to less sunlight), the cooler conditions allow for peak efficiency, meaning that the net electrical gain is most likely higher.

If you’ve previously been unsure about getting solar panels due to classic British weather, then worry not. The coldness of the weather evens out any darkness, and the constant deluges will provide free cleaning! If your concerns are assuaged, then fill out this form to be directed to solar panel providers near you, who’ll be able to tell you more.

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