Inside Clean Energy: Think Solar Panels Don’t Work in Snow? New Research Says Otherwise

Skeptics of renewable energy often claim—usually with an eye roll—that solar power doesn’t work well in snowy climates.

This idea was heavy when solar panels were stationary and only one-sided. Nowadays, most panels move along an axis to follow sunlight throughout the day. Additionally, increasing numbers of panels have silicon at the front and back. This makes solar more effective in areas where there is regular snowfall.

Here’s the latest: A recent paper led by researchers at Western University in London, Ontario shows that the use of “bifacial” photovoltaic panels—solar panels that take in sunlight from both sides—produces substantially more electricity during winter compared to using one-sided panels, based on data from a solar array that has both kinds of panels.

“I was surprised how striking the results were,” said Joshua Pearce, an electrical engineering professor at Western University and co-author of the paper. “There is no question now that bifacial modules are the way to go for ground-mounted PV systems in the north.”

The paper, published in Renewable Energy, shows how double-sided panels can absorb substantial amounts of energy from light reflected off the snowy ground. This is in contrast to PV Magazine’s description of the front of the panel being most likely to be partially covered in snow. 

Researchers visited a solar array in Escanaba in the Upper Peninsula of Michigan. They mounted cameras to observe snow cover, pyranometers to measure levels of solar radiation and also gathered electricity generation data from the system’s operator.

The snow-related energy loss experienced by the one-sided panels was 33% for the cold-weather months from November 2020 to March 2021. It was 16% for the two-sided panels. The study period covered 30 days of snowfall.

The reason researchers expected that the panels with two sides would show significant gains was that sunlight reflected off the snowy ground will hit the panels’ backside.

However, the team discovered additional benefits. The snow melted faster on two-sided panels that were not one-sided. This is likely because the panels got warm from absorbing light on the back side, but that’s just a guess since the researchers were not measuring the panel temperatures.

The paper builds upon a body of work that includes some from Western University that suggests what utilities should expect if they construct large solar arrays in locations that can get several days of snow.

I don’t want to overstate the findings. An array of solar panels in Arizona will still produce much more electricity than one in North Dakota. This is evident in maps showing the differences in sunlight levels across the country. The paper presents a less dramatic takeaway. Two-sided panels offer big benefits in northern climates, making them more financially attractive than the panels that were most popular a few decades ago.

One of the moving targets in research on solar panel output is that panels keep getting more efficient. Last week, the National Renewable Energy Laboratory reported that it had created a solar cell that was 39.5 percent efficient, which beats the lab’s previous record of 39.2 percent. A panel’s efficiency is a measure of how much of the sun’s energy can be absorbed and turned into electricity.

The record-breaking numbers are still achievable in a laboratory setting. The average efficiency of solar panels today is around 20 percent, which is a significant improvement over a decade ago.

The bottom line, which I discussed in January, is that developers are now able to generate more electricity per acre of sun power than ever before. This improvement is likely and will continue with every new generation of panels.

Two-sided panels play an important role in the growth of solar farms. According to Wood Mackenzie, they have accounted for less than 20% of all new panel sales in 2017, and will account for around 85 percent in 2021. (Figures refer to crystalline silicon panels that are used in utility-scale projects. This includes most of the global solar market.

“It pretty much happened instantaneously,” Kelsey Goss, a Wood Mackenzie solar industry analyst, said about the growth. “The door opened for bifacial products and pretty much all Tier 1 manufacturers shifted to make that product.”

Two-sided panels offer performance benefits with a small cost advantage, since costs have fallen along with market share. Prices vary by manufacturer, but Pearce sums up the differences by saying that two-sided panels are “only a few percent more costly.”

That only adds to the financial case for building more utility-scale solar, even in places where it’s not unusual to own snowshoes.

This week, there are other stories about energy transitions you should be aware of:

Hyundai announces a Georgian Electric Vehicle Plant:Hyundai Motor Group announced plans to invest $5.5 billion in a battery manufacturing plant and electric vehicle assembly plant near Savannah, Georgia. The plant could employ up 8100 people. The official announcement came during President Joe Biden’s visit to South Korea, where Hyundai is based. The plant is an economic development coup for Georgia, which is establishing itself as a center of EV and battery manufacturing, as J. Scott Trubey and Greg Bluestein report for The Atlanta Journal-Constitution. Rivian, a maker of electric trucks joined Hyundai in choosing the state to build a major facility. “I have the privilege, for the second time in the same fiscal year, to welcome the largest economic development project in the state’s history,” said Georgia Gov. Brian Kemp at the event to mark the announcement.

Officially Online: Texas has the largest battery storage system Vistra Corp. announced that its DeCordova Energy Storage Facility—which the company describes as the largest battery-storage plant in the state—is now online in Granbury, Texas. The 260-megawatt lithium battery system can run for just one hour before needing to be recharged. Sophia Beausoleil, NBCDFW, reports that the hybrid project combines batteries and a natural gas turbine to support the local grid. “With these batteries, they are charging at night for the most part when we’re not using power as much and all those wind farms are blowing across the state of Texas,” said Claudia Morrow, senior vice president of development for Vistra. “They’re charging with energy when it’s most available and then they’re going to put that power back onto the grid when our customers really need it.” The one-hour duration of the battery is on the low side for battery storage projects, indicating that Vistra wants this system to be able to provide a lot of power for a short amount of time, which is likely based on what the company sees as most needed in the region where the project is located.

A new proposal could make going electric for heat an easy choice:A new bill in Congress would increase domestic production of heat pumps by offering tax credits to manufacturers of $600 to $1,000 per unit that is sold. The measure’s lead sponsor is Senator Amy Klobuchar (D-Minn.). It aims to tackle one of the biggest obstacles in the transition to renewable energy: getting people to stop using natural gas as a heating source. Alexander C. Kaufman reports on HuffPost. This effort is crucial because heat pumps, which use electricity for heat and cooling, are essential. Costa Samaras, energy scholar, explains how heat pumps work. a Twitter thread, using the analogy of the McDLT, a sandwich sold by McDonald’s in the 1980s.

Global EV sales grew more each week in 2021 than in all of 2012The International Energy Agency published a report about the state of electric vehicle markets. It details a record-setting year 2021 and highlights some of the problems manufacturers face with a lack of critical parts. China saw a threefold increase in EV sales to 3.3million. In America and Europe, sales grew strongly. “Few areas of the new global energy economy are as dynamic as electric vehicles,” Fatih Birol, IEA executive director, said in a statement. “The success of the sector in setting new sales records is extremely encouraging, but there is no room for complacency.”

Duke Energy and North Carolina Solar Installers Reach Agreement on Net Metering Three of North Carolina’s largest solar installers have reached an agreement with Duke Energy. Duke will not implement any new rates for solar owners, which the solar industry considers to be harmful. The agreement still needs to be approved state utility regulators. This is happening while the state examines long-term changes in net metering, which is the system that compensates solar owners for excess electricity they send back into the grid. Emma Penrod reports on Utility Dive. This is just one of many examples of Duke collaborating with the Carolinas’ solar industry to avoid a more contentious process.

Inside Clean Energy is ICN’s weekly bulletin of news and analysis about the energy transition. Send news tips and questions to dan.gearino@insideclimatenews.org.