Solar Panels

Do Solar Panels Work in Winter?

By:Michael Johns

snowy solar panels

I get a little worried about solar panels during the winter, what if Santa Claus lands his sleigh on them?

Of course, I’m kidding, I know Santa is too magical to do any damage.

You probably aren’t hugely concerned about Santa, but are still wondering if solar panels are of any use during the colder months.

Well, the good news is that solar panels do still work during winter.

There are a few factors that affect performance at this time of year, both positively and negatively.

So huddle around with a hot drink, together we’ll go through solar panels’ winter performance, why it’s good, why it’s bad, and dealing with snow.

Santa clause on solar panels

Do Solar Panels Work in the Cold?

Yes, solar panels do work in the cold. In fact, the performance actually increases when temperatures drop.

It may seem counterintuitive, as solar panels are made to work with the sun, but they are more efficient in cooler weather.

But why?

It’s a common misconception that a solar panel generates electricity from both heat and light. In reality, it is only the sunlight and not the heat which creates the photovoltaic (PV) effect. This means the air temperature is irrelevant to electricity production. 

Actually, heat is not irrelevant, it is bad for solar panel performance. All solar panels have a temperature coefficient which tells you their efficiency based on temperature. 

The industry standard is for solar cells to perform at maximum efficiency up to 77℉ (25℃). Once they rise past this heat the performance will start to reduce. 

For example, an average panel will have a temperature coefficient of -0.5% / °C over 25°C. This means its efficiency will reduce 0.5% for every 1°C it rises above 25°C. 

That means at 30°C (86℉) you’d lose 2.5% efficiency.

That’s positive information for solar panel performance in the winter as it rarely gets this hot.

The cold weather stops this degradation and also increases energy production. This is because the electrons are more restfully spinning around the atoms inside the solar cell. When photons of sunlight hit the cell and charge the electrons the jump in voltage is higher and delivers more energy. 

How Effective are Solar Panels During Winter?

Don’t celebrate too fast. Although solar cells are more efficient in cold weather, there’s other factors that affect energy production.

solar panels under winter cloud

The biggest issue during winter is the reduced amount of sunlight. Quite simply there are fewer hours of sunshine and fewer peak hours. This varies depending on where you live. For example, the further away from the equator, like Northern US States or Canada, the shorter your winter days become.

As we know, solar panels require sunlight to work as less sunlight means less electricity production.

In addition, you might experience more adverse weather at this time of year including storms, snow, rain, and cloud cover. All of these block sun hitting your solar panels which significantly reduces output.

Do Solar Panels Work Better in Summer or Winter?

Solar panels will work better in summer than winter. When we add up all the considerations and look at the cold hard data the winner is clear. 

A solar panel delivers more electricity during summer than winter. When it comes down to it, the amount of sunlight beats all other factors. 

It’s so important that many homeowners report a reduction in electricity production of 70% to 80% during winter months. That means a solar array generating 300kWh in June and July may only deliver 75kWh in December and January… 

Once again, this output varies depending on your location but it gives you an idea of performance during a long summer day versus short winter days.

Do Solar Panels Work in Snow?

Yes, solar panels do work in the snow! If there is no build-up of snow blocking light hitting the solar panel then it will be beneficial to performance. 

With a covering of snow on the ground and surrounding areas the intensity of sunlight reaching solar cells increases. This is because extra light reflects off the white snow into the solar cells. Although we associate solar panels with warm summer, you’ll regularly see large solar arrays in snowy environments such as Alaska.

Solar panels in the snow

Think about when you have been around snow on a sunny day. Perhaps during a ski trip? You need to wear sunglasses or goggles because it’s so bright out! Well, solar panels love this bright light and generate more electricity.

It’s important to point out that this benefit only comes when no snow is covering the solar panel. A layer of snow covering over the solar panels will bring a halt to electricity production as light is completely blocked.

Should You Clear Snow Off Solar Panels?

So you need to ensure solar panels stay clear of snow to continue working properly. Does that mean it’s a good idea to remove snow quickly?

Generally, no, it’s not a good idea. This is because your solar panels are likely installed high on a rooftop so it will be dangerous to attempt the job. Adding to this, there is a risk of damage to the equipment as you clear the snow.

Actually, snow usually slides off solar panels relatively quickly. The surfaces are smooth and frictionless, so as soon as the sun reappears a little heat slides the snow right off. It’s like snow sliding down a car windscreen, which also helps to keep things super clean!

Snow sliding of solar panel roof

If your solar panels are accessible or mounted flat (on a van or RV for example) you might consider removing the snow. In this case, be very careful not to cause any damage. Walking across them or using sharp metal rakes will quickly lead to microcracks and even shattering. 

Should You Winterize Solar Panels?

There is no real need to winterize solar panels. They are incredibly durable and built to withstand most weather conditions. They can withstand strong wind, snow, rain, ice, and even hail.

Once installed there is very little maintenance required except cleaning and minor repairs.

In particular snow regions, snow guards can be installed. These are similar to snow spikes on roofs which stop large chunks of snow falling off. Snow falling from rooftops can be dangerous for people walking below. Clamps and spikes can be added to break up the snow slippage in this scenario.

Do Solar Panels Work in the Rain?

Yes, solar panels do still work in the rain but due to the cloud cover that arrives with this weather power output is dramatically reduced. You will find that the energy production during cloud cover reduces by 70% or more due to the lack of direct sunlight.

Water on solar panels

How Many Hours of Sun Do Solar Panels Need?

There are no set amount of hours required to make a solar panel work. When working out the size of the solar system required, installers compare data from energy usage and average peak sunlight hours per day in your region. Generally, you will find the average peak sun hours are between 3 – 5 hours per day. During these hours in the middle of the day is when your solar system will need to produce most of its electricity.

Final Words on Solar Panels in Winter

By now you should understand that solar panels still work in the winter. 

Although the cold weather helps efficiency you should expect a reduction in energy production due to reduced number of daylight hours.

In addition, more adverse weather will severely affect results, especially when cloudy. Snow can be both a help or a hindrance as it can offer increased reflected light but also completely cover over the solar cells.

So, yes solar panels will work in winter but you can see significant reductions in energy supply.