“The real novelty here is that the system, rather than the individual device, is doing the filtering and the smoothing,” says Nick Cravalho, ArrayPower’s vice president of business development.
Another key advance, Cravalho says, is the creation of three-phase rather than single-phase current. A three-phase signal combines three individual waves of alternating current of the same frequency that reach their peak voltage at different times. By emitting pulses for a sequence of three closely timed waves instead of a single wave, ArrayPower’s sequenced inverter stores smaller amounts of electricity for shorter durations. As a result, the company can use inductors rather than capacitors for energy storage, thereby reducing cost and increasing the life expectancy of the device.
“The electronics look very simple,” says Daniel Kammen, director of the Renewable and Appropriate Energy Laboratory at the University of California, Berkeley. Kammen is not affiliated with the company. “It’s basically a series of wave amplifiers working in concert with each other, allowing for devices that should be very robust.”
Kammen says that while the technology looks promising, longer field trials will be needed to prove the long-term durability of the devices.
ArrayPower has partnered with Canadian Solar, one of the world’s largest solar panel manufacturers, to integrate the inverters into the company’s crystalline panels. The companies have conducted field tests of the integrated panels for seven months, and Canadian Solar says it plans to begin shipping the combined panel plus inverter units this quarter.