The device adds about 12 cents per watt to the installation cost of a photovoltaic system but pays for itself within two years for most installations. In addition, installers don’t have to worry about, say, the shifting shadow of a chimney or the precise tilt angle of each panel. “It can simplify design time and reduce installation time so their profit margin goes up,” Kayser says.
Suntech hasn’t put all its eggs in one basket. The company is also looking at microinverters, another electronic technology expected to boost photovoltaic power. Microinverters adjust the voltage-current levels of each panel, and then go one step further: they convert the panel’s DC power to AC.
The two approaches have their pros and cons. Microinverters make it simpler to wire panels together, so new photovoltaic systems are easier to install, and it’s also easier to add panels to an array later. But it’s easier to retrofit existing systems with power optimizers–and Kayser says they should also offer better overall system efficiency. That’s because converting DC to AC at each panel, as microinverters do, requires stepping up each panel’s low operating voltage of around 30 volts to the grid-standard 120 volts, leading to some power loss.
Suntech has teamed up with half a dozen companies that make microinverters and power optimizers. These include the startups Enphase Energy in Petaluma, California; Tigo Energy in Los Gatos, California; and Azuray Technologies in Portland, Oregon. Tigo makes a DC power optimizer that adjusts panel current levels and can increase power output by up to 20 percent. Enphase claims that its microinverters can help solar systems harvest up to 25 percent more energy. Azuray, meanwhile, is making both power optimizers and microinverters.
While both technologies have been around for two decades, they have only recently been implemented in low-cost, reliable products, says Eric Wesoff, a solar analyst at Greentech Media. “Panel manufacturers have finally been convinced that this is something that can last,” he says. And as engineers max out other means of increasing the efficiency of photovoltaic arrays, they’re more willing to try different electronics. At least 20 different solar-electronics startups showed off their products at the Solar Power International conference in Los Angeles this week.
Wesoff adds that Suntech is taking the smart, cautious approach by partnering with multiple microinverter and power-optimizer vendors. “Clearly they’re not picking a winner or an architecture,” he says.