Vertical rooftop PV performs better than conventional rooftop solar under the snow

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Vertical rooftop solar panels outperform conventional systems during snowy months, Norway’s Over Easy Solar has found. The company, which manufactures vertical PV units, said it conducted a case study research in Oslo, and that the yield from the vertical panels remained consistent through early spring, even after fresh snowfall.

“Our data shows that the yearly energy yield of vertical solar panels can be the same or up to 30% higher than for conventional flat roof solar installations,” company founder and CEO Trygve Mongstad told pv magazine. “In the winter months in Norway, the energy generated is 3-4 times more for vertical solar panels than for conventional flat roof solar mounting.”

The company explained that vertical panels perform better under low snow cover of up to 10 cm and under partial snow cover of up to 30 cm. In low snow cover, they benefit from increased albedo due to the snow; in partial snow cover, panels continue to capture sunlight while sticking out of the snow.

“The part covered by snow will not produce anything, but the way the solar panels from Over Easy Solar is designed, partial snow cover will not greatly affect how the uncovered part of the solar panel produces,” the company said. “However, vertical solar panels that are completely covered by snow will not produce any electricity, same as for conventional tilted solar panels.”

Another benefit of vertical panels in snow conditions, the company claims, is the faster melting of snow around them. That is as the panel orientation promotes the mixing of warmer air into the snowy surface. In addition, they say, the vertical panels capture heat when the sun is shining, speeding up the thawing of adjacent snow.

“In addition, solar installations with vertical panels have less likelihood of damaging the roofing membrane or insulation typically used in cold climates,” Mongstad added. “Our product was developed with the needs of solar installers and building owners in mind after my team and I have worked many years with flat roof solar installations in Norway.”

In August, Over Easy commissioned what it describes as the world’s largest rooftop vertical bifacial solar installation in the world to date. It was installed at the Norwegian national football stadium.

The 284.4 kW system features 1,242 vertical photovoltaic units of 200 W each supplied by Over Easy itslef. Over Easy Solar’s XM-2 Quattro-200S vertical panels feature silicon heterojunction cells and a module architecture that reportedly offers a bifaciality of 95.7%. The panels are also claimed to be low-weight, adding less than 11 kg/m2.

It also deployed a 102 kW installation covering 1200 m2 on a flat-roofed commercial building in Oslo.

Over Easy has a novel, low-height, all-in-one system design for flat rooftops. Its systems are delivered to the installation site in a pre-assembled single unit that includes its unconventional heterojunction bifacial modules, the mounting rack, and the cabling.

The company calls its prefabricated product a “vertical photovoltaic (VPV) unit” and each one has an output of 200 W. They come in two sizes, one for green roofs, with a size of 1,600 mm x 1,500 mm x 345 mm and a weight of 26 kg, and one for roofs without vegetation, measuring 1,600 mm x 1,500 mm x 265 mm and weighing 25 kg. The clearance for both products is 120 mm and 40 mm, respectively.

 

 

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