by Martin LaMonica
Start-up GreenRay Solar has raised money to finalize development of a solar panel that puts out household-grade alternating current, a technology that backers say will make solar power more accessible to homeowners.
The Westford, Mass.-based company said that it has raised $2 million from the Quercus Trust and 21Ventures, which will allow it to start production of its solar panels in the fourth quarter this year. Since its founding three years ago, the company had raised $3.5 million in state and federal clean-energy grants.
GreenRay's AC Solar Module will turn out electricity that meshes with household alternating current and voltage. Solar panels put out direct current, and then an inverter, typically placed in a home's basement or outside the house, converts the direct current to alternating current.
Instead of a large inverter for many panels, there are a number of companies developing microinverters that do the DC-to-AC conversion right on the panel.
This design simplifies installation and offers a number of other benefits, said GreenRay CEO Miles Russell. Cutting out the single inverter is safer because installers are dealing with lower voltages.
Microinverters also make an array deliver more reliable performance, say advocates. When one direct current panel is shaded, that drops the performance of all the panels connected to it. Also, it's easier to gather data on an array's performance, Russell said. GreenRay's panels will transmit performance data over the wires and transmit it to the Web via a gateway, he said.
Does this mean that installing solar panels is a do-it-yourself job? Russell said that very handy people could install GreenRay's 200-watt panel, but they are electrical appliances so require typical safety precautions and inspection.
"The do-it-yourself moniker is more of a long-term objective. You could imagine them at a Home Depot and they could be installed for an extra fee," he said.
Another advantage of AC solar panels is that a person could install only a few, rather than a full array, without the cost of an inverter. On the other hand, microinverters do add cost to a solar panel, which is one reason that microinverters have not been commercialized in the past.
Martin LaMonica is a senior writer for CNET's Green Tech blog. He started at CNET News in 2002, covering IT and Web development. Before that, he was executive editor at IT publication InfoWorld.