High-latitude tests show vertical rooftop PV yields 30% more energy

Norwegian startup Over Easy has reported the initial results of its vertical bifacial rooftop PV system, which uses specially designed solar modules. The Norwegian Institute for Energy Technology (IFE) supported the company in measuring the performance of the array, which is located in Vestby, near Oslo.

“Overall yearly specific yield is up to 30% higher than for conventional flat roof solutions,” CEO Trygve Mongstad told pv magazine.

In 2022, the vertical PV system generated 1,070 kWh per kilowatt installed. Mongstad says this compares to around 800 kWh per kilowatt installed for a conventional rooftop array installed in the same location.

“Two other 5 kW installations with HJT cells have also been in operation since February and May 2022 in Oslo, Norway, and have showed over 30% higher energy yield in the periods compared to conventional 10-degree tilted flat roof solar installations,” Mongstad added. “Snow is normally not a problem for the energy production, the panels are sticking up on the rooftops even with 1 m snow on the ground.”

The company currently uses PERC cells with a bifaciality of 77% to 81% or HJT cells with bifaciality of 90% in its demonstrators.

“The ground cover ratio of the installations is about 50%,” Mongstad explained. “The solar panels are about 20 cm tall and the pitch between the rows is 40 cm. The installations were placed on generic dark or lighter gray bitumen roofing membranes.”

The units include a mounting system and solar panels in a single pre-assembled package, which the manufacturer said makes them easily mountable. Every unit measures 1,600 mm x 1,510 mm x 350 mm and weighs 24.5 kg. They also feature an IP68 enclosure rating and 3.2 mm double-tempered glass.

Over Easy said it plans to work with production partners in China and Spain and aims to begin producing the solar modules in the fall. Currently, it uses solar cells provided by undisclosed Asian manufacturers.

“We are doing assembly at locations in Norway and Spain, and the units for our pilot installations so far are 100% manufactured in Europe, including the solar panels,” Mongstad told pv magazine in May.

*The headline of the article was updated on March 29 to reflect that the 30% higher energy yield is achieved on a yearly basis and not in winter.