As noted in this month’s feature article on thin films (page 36), the low cost, light weight and slimness of solar film allow it to be installed flush to a surface, opening up an entirely new realm of applications beyond rooftops. These other applications include glazings, skylights, windows, walls, and awnings.
Nevertheless, for maximum exposure throughout the day, rooftops present the optimal position from which to track the sun. And unlike the bulkier crystalline PV panels and their racking systems, thin film on rooftops reduces wind uplift and may require fewer penetrations. At last month’s International Roofing Expo, a diverse group of suppliers displayed thin-film products or products designed to accommodate the technology.
Building owners interested in the thin-film technology need to cover their bases when considering its implementation. Heat is one issue. Suppliers at the Expo had new membranes designed and warranted to accommodate the added heat that dark film generates on the roof surface. Thin film’s current technology also produces fewer watts per square foot than crystalline PV panels. Methods of adhering thin films to the roof are another issue. Roof manufacturers want to approve any adhesive that will be used to attach thin film to their membranes.
The adhesive factor for installation can be resolved by using products manufactured with the films. Such products on display at the Expo include single plies and a thin-film laminate for standing seam roofing. Lightweight tilted platforms for thin films improve exposure to the sun. A design incorporating cylinders wrapped with thin film on racks above a cool roof not only increases exposure through the day but also catches light reflected by the membrane underneath.
While the versatility of solar film technology is alluring, it has yet to match the output of crystalline PV panels. But the benefits are sure to spur research into ways of increasing output, which could result in a win-win for building owners.