With solar panel prices falling more than 80 percent in the last few years, many solar companies are turning their attention to reducing the cost of installing them. Two leading solar companies, Solon Energy, based in Berlin, and Trina Solar, based in Changzhou, China, have announced new designs for mounting solar panels to roofs—the companies say these designs can reduce the installation time by more than half, greatly reducing labor costs. The new designs reduce or eliminate the tools and hardware needed to install solar panels, and standardize solar installations, which have largely been ad hoc, reducing the time needed to design them.
While solar panels themselves used to account for most of the cost of large solar installations on commercial rooftops, the modules now account for about 40 percent of the cost. The rest comes from things like the necessary hardware, power electronics, and labor—which alone accounts for about 30 percent of the total.
Mounting solar panels on the flat rooftops of commercial installations typically involves anchoring long metal racks to the roof to create a framework that will angle the panels toward the sun and hold them together. Installers bolt the panels to this frame, wire the panels together, and electrically ground the racks.
Trina’s design gets rid of most of this metal framework. It starts with some simple changes to the solar panels themselves. Solar panels resemble framed pictures—they consist of solar cells sealed behind a piece of glass and held in place and protected by a metal frame. This frame is typically bolted to the metal rack framework that angles the panel toward the roof. Trina uses the frame of the solar panel itself to provide the framework. Special hardware locks into grooves cut into the frame, propping the panel at the correct angle without the need of any tools.
The company says this reduces installation time by two-thirds, and reduces the chance that stray bolts and screws might get caught under the framework and damage the roof. Savings in materials and labor costs can add up to a 10-cent-per-watt reduction in costs for solar power, a significant drop considering that solar panels now sell for less than $1 per watt.
While Trina modifies the solar panel’s metal frame, Solon eliminates it altogether. It takes an array of solar cells that have been sealed behind a layer of glass and then glues that to a plastic form that angles the cells toward the sun. This complete module is assembled in a factory, reducing the amount of work that needs to be done on site. Installers set the modules on the roof, link them together with plastic connectors (they also add some ballast), and plug wires together to establish electrical connections. Because the modules have no exposed metal, it isn’t necessary to ground them, which helps reduce costs. Solon says the design reduces the time needed for mechanically mounting the panels by 75 percent, and the time needed for making the electrical connections by half. (Solon says that the impact on costs varies widely, depending on factors like labor costs.)
Both designs come with some trade-offs—for example, to achieve economies of scale, the systems provide only one standard angle for pointing the panels at the sun. At some latitudes, the panels would generate more power if they were tilted more or less than that angle.