The most obvious way to maximize a building's solar energy production is to cover every square inch of the roof with solar panels, but developers say choosing the right inverter also can help boost a system's production.
Inverters are a key component in a solar project, converting the direct current electricity from solar panels into the alternating current power needed by buildings.
"There are two major options for inverters," said Paul Keuhn, managing partner at Deutsche Eco, a German company with its U.S. headquarters in Kenilworth. "You can have one for the entire system, or you can break it up."
The Institute for Electrical and Electronics Engineers, in Piscataway, chose the latter. In February, Deutsche Eco completed a 101.55-kilowatt rooftop system using a network of four commercial-grade string inverters manufactured by the German firm REFUsol. IEEE now has a total of 370 kilowatts worth of solar, accounting for 50 percent of energy use at the building.
The IEEE project is Deutsche Eco's first in the United States, though the company has a long history in Europe. The company partnered with Randolph-based Solus Energy on the project.
Keuhn said one advantage of using smaller inverters is size. Traditional inverters that are tied to an entire solar array can weigh thousands of pounds, so they are more difficult to install and often too heavy for a rooftop. Each of the IEEE inverters weighs about 100 pounds.
Keuhn said using multiple inverters also can give the user more control over the system's efficiency, because it allows the system owner to monitor the efficiency of smaller sections of panels.
"You end up with four efficiency trackers, as opposed to just one, which means you can be more efficient with the sun that you've got," he said.
That's important, because the production of a given panel can be affected greatly by shadows, clouds and other factors.
Keuhn said using the REFUsol system is "marginally" less expensive than using a single inverter, though he said the main difference is in the system's production over its lifetime. Small differences in production can add up to major savings over time. Keuhn said that's a big selling point for businesses.
"You want to know that when you put this installation in, that it's going to produce as much energy as it can for your dollars," he said. "With a string inverter, you're really at the point where you're able to offer them greater efficiency for a very similar dollar."