Do Solar Panels Melt Snow?

Do Solar Panels Melt Snow?

With winter weather comes falling snow, and for homes with solar panels, snow accumulation can reduce solar production. Most homeowners wonder – will the dark solar panels attract enough heat from the winter sun to melt away the snow? The answer is more complex than a simple yes or no. While solar panels can warm up and melt some snow, their snow clearing abilities depend on various factors.

Solar panels work by absorbing sunlight and converting it to electricity through the photovoltaic effect. But when solar radiation hits the panels, some of that energy gets converted to heat instead. So even on cold winter days, solar panels warm up significantly compared to ambient temperatures. This heat generation offers the potential to melt snow – but solar panel temperatures are influenced by many variables.

How Solar Panels Work

Solar panels work by converting sunlight into electricity using photovoltaic cells. When sunlight hits the solar panel, it excites the electrons in the silicon cells, causing them to flow and generate an electric current. This process is known as the photovoltaic effect. Specifically, photons from the sunlight dislodge electrons in the semiconductor material of the solar cell, allowing the electrons to move between positively charged silicon atoms and negatively charged phosphorous atoms. The movement of electrons between the positive and negative sides creates an electric field that causes electricity to flow (1).

Solar cells are assembled together in modules to form solar panels. The direct current (DC) electricity generated by solar panels is fed through an inverter, converting it into usable alternating current (AC) electricity that can power home appliances and devices (2).

(1) https://www.energysage.com/solar/solar-panels-work/
(2) https://www.solar.com/learn/how-solar-panels-absorb-and-store-energy/

Solar Panel Materials

Solar panels are typically made of glass, aluminum, copper, and silicon. The key component is the solar cell, which is commonly made of crystalline silicon. This semiconductor material is treated to form an electric field that generates electricity when exposed to sunlight (Source 1).

The silicon solar cells are protected by a glass sheet on the top side facing the sun. This is usually a low iron, tempered glass with anti-reflective coating to maximize light absorption. On the back side, the cells are often encased in ethyl-vinyl acetate and a polymer backsheet (Source 1).

The aluminum frame provides structural support and allows the panels to be mounted. Copper is also used for internal wiring to conduct the electricity generated by the cells. Though silicon is the primary active material, solar panels do contain other common materials like glass and aluminum (Source 2).

Solar Panel Temperatures

Solar panels can reach high temperatures on hot, sunny days. According to Energysage (https://www.energysage.com/solar/solar-panel-temperature-overheating/), solar panel temperature typically ranges between 15°C and 35°C. However, on very hot days, solar panel temperature can climb as high as 70°C.

The key factors that affect solar panel temperature are ambient temperature, solar irradiance levels, and wind speed. On hot, sunny days with little wind, solar panels can absorb a lot of heat from the sun’s rays. This builds up and causes the panels to reach very high temperatures. Thermal imaging shows panel surfaces exceeding 70°C in these conditions.

Solar panels are designed and tested to withstand these high temperatures. However, higher temperatures do cause solar panels to become slightly less efficient at converting sunlight into electricity. Most solar panels will experience a 0.4-0.5% drop in efficiency for every 1°C increase above 25°C. So on a very hot day, efficiency could drop 10-15% below peak levels. But the panels will continue operating safely up to around 85°C.

Factors Affecting Snow Melting

There are several key factors that determine how quickly snow will melt, including:

Ambient Air Temperature

Warmer air temperatures cause snow to melt faster. As air temperatures climb above freezing (32°F/0°C), the rate of snowmelt increases. According to one source, snow melts fastest in temperatures from 35-45°F (2-7°C) (https://www.dtn.com/what-factors-determine-how-fast-snow-melts/). The warmer the ambient temperature, the more energy is transferred to the snowpack, accelerating melt.

Sun Exposure

Exposure to direct sunlight dramatically increases snowmelt rates. Sunlight delivers radiant energy that heats up the snow surface and the surrounding air. According to one expert, net incoming solar radiation is a primary factor in snowmelt (http://www-das.uwyo.edu/~geerts/cwx/notes/chap10/snowmelt.html). As snow ages, its albedo (reflectivity) decreases, allowing it to absorb more incoming solar radiation and melt faster.

Wind

Wind contributes to accelerated snowmelt by replacing the layer of air above the snow with warmer air from above. Wind also increases evaporation and sublimation losses from the snow surface. Finally, wind drives turbulent mixing which transfers heat into the snowpack (https://www.actionnews5.com/2021/02/22/breakdown-why-snow-melt-can-be-long-process/).

Precipitation

Additional snowfall on top of existing snow acts as insulation, slowing the melt rate of the original snow underneath. Rain falling on snow will melt the snow and speed overall melt. However, rain quickly freezes if temperatures drop below freezing again.

Humidity

Higher humidity levels in the surrounding air can accelerate snowmelt, while low humidity can slow melt rates. Humid air transfers moisture and latent heat to the snowpack.

In summary, the most important factors affecting snowmelt are ambient air temperature, sun exposure, wind, precipitation, and humidity.

Solar Radiation Effect

Solar radiation refers to the electromagnetic waves emitted by the sun that reach the earth. These waves deliver heat and light energy that can warm surfaces on earth and melt snow (1). Research has found that solar radiation is a key driver of snowmelt, especially during the spring (2). The sun’s rays heat up solar panels and the surrounding surfaces, which can increase melting of snow accumulated on top of the panels. South and west-facing panels tend to receive more direct sun exposure. Solar radiation melts snow most efficiently on sunny days and at times when the sun’s rays directly strike the panels at a perpendicular angle.

(1) https://phys.org/news/2006-07-ice-sheets-atmospheric-carbon-dioxide.html

(2) https://digitalcommons.cwu.edu/cgi/viewcontent.cgi?article=1645&context=etd

Case Studies

There are several real world examples demonstrating the ability of solar panels to melt snow that accumulates on top of them. According to a Quora post, solar panels with only a thin layer of snow covering them will melt the snow due to the heat the panels generate (1). This is possible because solar panels are designed to absorb as much solar radiation as possible, converting it into electricity. This absorption of radiation generates heat as a byproduct.

In a study conducted at the University of Massachusetts Amherst, researchers found that solar arrays cleared themselves of snow buildup faster on sunny days compared to cloudy days when solar radiation was lower (2). The solar panels generated enough heat from the sunlight to melt the snow on top of them. The angle of installation also played a role, with steeper angles shedding snow more easily than flatter angles.

There are real world solar farms that experience heavy snowfall during winter months but are able to successfully melt accumulated snow on the panels through solar heat generation. For example, the South Kent Solar Farm in Connecticut receives regular snowfall but utilizes solar energy to clear the panels (2).

Sources:
1. https://www.quora.com/Do-solar-panels-melt-snow
2. https://quizlet.com/576656713/bio-171-lecture-12-global-climate-change-ii-flash-cards/

Installation Angle Considerations

The angle at which solar panels are installed plays an important role in allowing snow to shed off the panels. According to Optimum Tilt of Solar Panels, solar panels should be tilted at an angle optimized for winter sun exposure to promote snow shedding. The ideal tilt angle to prevent snow accumulation and allow it to slide off is equal to your latitude plus 15 degrees. For example, if you live at 40°N latitude, the optimal panel tilt angle would be 40 + 15 = 55° for winter months. This steeper angle allows the sun’s radiation to hit the panel more directly, warming it up to help melt and shed snow.

As explained on Solar Panel Angle, adjusting the tilt angle seasonally can maximize solar energy production. In winter, tilting panels at latitude plus 15° promotes snow shedding. But in summer, tilting panels at latitude minus 15° can capture more sunlight as the sun’s path changes across the sky. Adjustable tilt mounts allow homeowners to easily change the angle twice a year for optimal energy production and snow shedding.

Other Snow Removal Methods

Aside from allowing solar radiation to naturally clear snow off panels, there are some manual and technology-based methods homeowners and solar farms use to remove snow from solar panels. These include:

Heated Solar Panels – Some newer solar panel models come equipped with heating elements that can melt snow. These heated panels utilize electricity to raise the surface temperature high enough to clear snow. Heated solar panels are more common for large utility-scale solar farms, as the energy required to heat numerous residential panels can diminish cost savings from solar generation during winter. One study on solar panel snow melting found heating elements were most cost effective for climates that receive heavy snowfall frequently throughout winter (Beattie, 2021).

Manual Cleaning – Homeowners have options for manually removing snow from solar panels, though this requires periodically clearing snow after fresh storms. Tools like telescoping poles, brushes, and squeegees allowreaching panels on high rooftops to brush or squeegee off accumulated snow. Care must be taken not to scratch the glass when manually cleaning off panels. Some even use leaf blowers to blow snow off panels from the ground, though this is less thorough. Large solar farms may utilize manual shoveling or plowing, but have much more area to cover.

Snow Rakes – Specialized solar panel snow rakes have emerged as another manual snow removal option. These rakes are designed with soft bristles and adjustable poles that extend up to rooftop solar arrays (iconicnrg.com, 2022). The bristles gently clear snow off panels after accumulating. For steep roofs or hard to reach areas, extension poles allow clearing panels from the ground. Like manual cleaning tools, snow rakes require periodic use after snow storms. They provide a simpler way to clear panels versus climbing on the roof.

Conclusion

In conclusion, the answer to whether solar panels melt snow is not a simple yes or no. Solar panels can reach temperatures warm enough to melt snow and ice, but many factors come into play.

The key factors that determine a solar panel’s ability to melt snow include the panel’s efficiency, material composition, tilt angle and direction, and the amount and type of winter precipitation it receives. Higher efficiency panels like monocrystalline silicon tend to run at warmer temperatures and are more likely to melt snow. Steeper tilt angles also increase snow-melting capability.

Even with an ideal panel setup, full snowmelt is not guaranteed. The best solutions are to clear snow manually when needed, choose high-efficiency panels, increase panel tilt, and consider selective snow barrier installation to protect equipment.

Overall, solar panels can be an effective tool as part of a snow management strategy, but work best when paired with other snow removal methods.