Photovoltaic projects are getting larger, Travis Bradford, president of the Prometheus Institute, said at a Greentech Media conference Wednesday.

According to numbers from Larry Sherwood, a board member at the Interstate Renewable Energy Council, projects with the capacity to produce at least 500 kilowatts of direct current grew from 9 percent of the total U.S. photovoltaic capacity in 2004 to 29 percent – and more than 40 megawatts – in 2007.

The average nonresidential U.S. system size surpassed 65 kilowatts in 2007, according to numbers from Sherwood that Bradford presented at the Massachusetts conference.

“We expect that trend (of larger systems) to continue in the U.S. and also in places like Spain,” Bradford said. “The average U.S. system size has clearly been growing.”

The trend is good for concentrating solar-thermal technologies, he said, because at projects of 100 megawatts and up, it makes sense for utilities in some locations to consider concentrated solar-thermal projects. 

Concentrated solar isn’t competitive at smaller sizes, “but if you talk about 100 megawatts-plus for utilities, all of a sudden they will be making a decision between PV and CSP systems,” he said.

Companies such as BrightSource, Abengoa Solar and Ausra are planning projects with capacities in the hundreds of megawatts (see Solar Temblor: Larger is Better, Ausra to Build 177-Megawatt Solar-Thermal Plant and Ausra to Build World’s Largest Solar-Thermal Factory).