Most people don’t give the color of their roofs a second thought, but it could be costing their business a lot of money.
White or light gray roofs can increase rooftop bifacial PV energy yields by up to 25 percent and increase the return on investment by up to 10 percent, according to new research by Opsun, a bifacial PV racking company.
Other companies are improving performance more directly. According to Reuters, a German company called Enerparc improved their bifacial performance by adding a field layer — they covered the ground with gravel, which reflected more light on the panels. They also found that performance changed with the season, improving during the winter when there’s presumably ice and snow on the ground.
Elevation, racking tilt and local factors also affect bifacial PV performance, making estimating feasibility a difficult process according to an article in Solar Power World.
Bifacial PVs have solar cells on both sides and turn light into useful energy that would normally be reflected away or absorbed as heat, according to Energy Sage. They have limited residential applications because they need to be mounted at an angle to allow light to reach the reflective surface. As such rooftops and parking lots for many businesses are the ideal locations. Some mounting systems, however, can shade the panels, reducing effectiveness.
In the past, predicting power yields has also been difficult, which makes financing installations more uncertain.
But Opsun believes they’ve changed that with their “Opsunizer” tool, which can compare bifacial and monofacial installations in the same location. According to Opsun, the tool is a very basic layout simulator that lets the user adjust the tilt and elevation from the rooftop of PV systems, as well as compare outputs and returns on investment, creating an estimate of possible gains from using a bifacial system.
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