How Does Winter Impact Solar Panels?

As 2013 turned into 2014 a “Polar Vortex” swept across the Midwest and Northeastern United States. The entire state of Indiana was under a winter weather warning, and the NWS said 8-12 inches of snow would be on the ground. With wind drift that number ended up close to 22-26 inches. Subzero temperatures smashed records in Chicago, which set a record for the date at minus 16, and Fort Wayne, Indiana, where the mercury fell well below minus. Coupled with clouds and wind chill the cold turned deadly for some: Authorities reported at least 21 cold-related deaths across the country, including seven in Illinois, and six in Indiana.

Dealing with solar panels during an Indiana winter - Solar Power Works In Winter

According to Mike Tobias, Inside Sales Executive of Solar Energy Systems, located in Nappanee, Indiana “during bad weather like we recently experienced people often ask ‘ will solar panels work in Winter?’ … they also want to know if the ice and snow will damage their solar system.”

Source: Fox News and NBC News

The PowerHouse In The Sky

The short answer is that from a peak pure performance point of view, solar panels actually perform better in colder conditions than they do in the heat of summer.That said, from a peak output perspective solar panels produce less total energy during winter, but that’s the result of fewer daylight hours, not the temperature.

One of the biggest myths about solar panels is that excessively cold winter temperatures will prevent the panels from operating correctly. The reason this is not true is that solar panels, also known as, Photovoltaic [PV] modules work on light being the resource, not the presence of heat.

Milk Farmer Solar Energy - Dairy Farmers Solar Energy -

Image Source: Longacre’s Modern Dairy

For example, imagine you work for a dairy farmer and you are responsible for checking the ice cream inventory. You enter into a walk-in freezer with a solar-powered calculator to perform your calculations. Will your calculate work?

Of course it will. But, why? So, it warm in there? No, the milk would spoil. Is there sunlight? Probably not. Yet, that calculator will turn on and work, so long as the light bulb [hopefully an Ameri-Light LED] in the walk-in freezer works and outputs sufficient light.


Example : Calculating Output of a Solar Energy System in South Bend, Indiana

Using the Gaisma website which provides sunrise, sunset, dusk and dawn times for thousands of locations all over the world. Solar Energy Systems,llc is  able to forecast the length of daylight to establish production of different PV modules with a fair degree of accuracy. In this example, a home in South Bend, Indiana.

One caveat is that this does not take into account overcast weather conditions, which will cause a slight decrease in harvesting production, not functionality of energy output, but that’s the case during any time of the year, including Summer.

Gaisma - Sunlight Output in South Bend Indiana Solar Energy Systems - Solar Power Works In Winter

Figure 1 – Gaisma Sun data forecasts lengths of Sunlight for South Bend, Indiana

A Deeper Understanding of the Sun and Its Light Power

Now, that you know photo [light] voltaic [power] is the resource  that triggers solar panels to work, a better understanding of the sun as a light resource will clarify why peak pure performance in better in colder conditions than in the heat of summer.

You probably already know that all the planets and the Sun make up our solar system. But, did you know the Sun actually lies at the very center and it is larger than all the planets combined. Deep inside the Sun, exploding gases release incredible amounts of energy, which allows it to be the source of energy for our entire solar system.

Solar Power Works In Winter

Scientist believe it takes one million years for the Sun energy to reach the Sun’s surface. Then, the energy begins its journey into outer space, and since the planet Earth is about 1.3 million times smaller than the Sun only a small fraction of the Sun’s energy reaches Earth. Despite this on a cloudless day, Earth receives enough solar energy to power all our homes and buildings.

Sunlight is highly reflective and as a result on a sunny day following a snow storm it is possible for a Solar Energy System to harvest a temporary boost to electricity production due to sunlight reflecting onto solar panels, much like a teenage can get a sunburn on a sunny winter day of hitting the Paoli Peaks ski slopes.

The Problem With Solar Panels and  PV Power Systems In Winter

Solar Power Works In WinterWhile the reflective properties of snow are a benefit during the Winter, a Solar Energy Systems can only maximize this benefit if your solar panels are clear of snow.

CNET’s Martin LaMonica, recently wrote a post for CBS News titled Solar Panels Mean  An Extra Winter Chore. He starts by saying …

Here’s a chore I didn’t expect to have this winter: removing snow from my solar panels. As anybody who lives in New England knows all too well by now, we’ve had a snowy winter. I like snow so, overall, that’s just fine with me. But the white stuff delivered an unexpected hit to the electric output of the solar panels I had installed last spring. It’s hard to calculate a precise impact, but my December electric bill offers a clue: it’s more than twice the previous month.”

Martin goes on to recommend a roof rake for the do-it-yourselfer, but, there are other cost-effective options.

The first are Solar Panel Heaters made by UHI Worldwide. These flat heater are applied underneath solar panels and have two installation options; (1) retrofit with an automatic light and temperature sensor, (2) retrofit with a manual electric switch. At around $100 – $150 with a lifetime manufacturer warranty these panels pay-off of themselves quickly.

Another other option offered by several solar panel installers is a Solar Energy System maintenance program.  So, you do not have to clean the panel off yourself.

What happens if I am unable to clean snow off my solar panels?

Solar Power Works In Winter - Waiting for snow to melt on solar panelsAnother myth about solar panels is that due to snow buildup on the panels, they will not be exposed to sunlight and therefore your Solar Energy System will stop working. While yes, your solar panels will temporarily not be able to  harvest new sunlight your Sun power system will continue to output stored energy.

Where does this stored solar energy come from?

Throughout the year, photovoltaic cells within your solar panel have converted sunlight into electricity, which is either used immediately or stored in batteries for future use in your own back-up source  or through the utility power grid. This acts as a safety net, making up for any shortfall in solar power output.

Read This Blog About Alternative Solar Back-up Power Here >>>

Example An Indiana Farm Using A Solar Energy System During 2014 Polar Vortex

Solar Edge monitoring of Solar Energy Systems for an Indiana Farm During Winter

Figure 2.1 – Solar production paused by snow blockage for Jan. 5 – Jan. 10 2014


Using the Solar Edge monitoring system, we can see a five day drop off of sun power harvesting by the Hand Farm in Indiana. [ Figure 2.1]

Solar Energy System works in winter - Snow does not stop system for working, but, does pause production.

Figure 2.2 – Solar Energy Harvesting in 2013 keeps system works despite no new production.

Despite the drop off of new energy production during the early 2014 storm, they maintained power from the energy they collected in late 2013.

CONCLUSION : Solar Power Works In Winter

Everyday we are discovering ways to harvest that power to help meet our future needs. Best of all, power from the Sun is a renewable, sustainable, and possible.

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