Small Solar Power Generators Need Grid Interface Help

The DOE funding, which requires Congressional approval, would pay two-thirds the cost of the projects, with another $1.7 million to be contributed by private industry.

The program overseeing the projects, managed by Sandia National Laboratories in New Mexico, is known as Solar Energy Grid Integration Systems. Its focus is stitching together individual solar photovoltaic generating systems with the nation's complicated electricity grid.

Integrating thousands or more separate PV systems into the country's delicately balanced electrical highway is a puzzle in a variety of ways.

This micro-inverter (top) and communications gateway help connect individual solar systems to the grid. (Photo courtesy Enphase Energy Inc.)

One key reason is that the existing utility grid was designed for power to flow one way - from large generating stations to consumers.

With the proliferation of consumer-owned PV systems connected to the grid, electricity generation is becoming a two-way street as consumers generate their own electricity and sell whatever they don't use back into the grid.

For the grid as a whole, the growing popularity of solar and other small generate-it-yourself systems can contribute to instability and potentially unsafe operations, according to the DOE.

The energy agency points out that clouds gathering and clearing can cause PV power output in a given service area to rise or fall quickly, so production of solar power may not match the times when power is most needed, such as late afternoon and early evening.

PV systems are designed to disconnect automatically if voltage sags on the system, such as during times of high demand.

Still, owners of the disconnected systems continue to draw electricity, which could result in a significant increase in demand, aggravating the cause of the voltage sag and contributing to a blackout.

Today, with solar power contributing less than one percent of electricity generation in the country, such issues are inconsequential. But as consumer demand and government policy boost America's reliance on the Sun, solving the technical challenges becomes more urgent and necessary.

The projects the DOE said it hopes to support focus on conceptual design of hardware and market analysis, and point toward developing products that maximize the value of PV systems and give consumers greater control of their electricity consumption and costs.

"Our investment in these grid integration projects will lay the groundwork for high levels of solar photovoltaic market penetration," said John Mizroch, DOE principal deputy assistant secretary for energy efficiency and renewable energy in a statement.

Mizroch cited the Solar America Initiative championed by President George W. Bush, which hopes to make solar energy cost-competitive with conventional sources of electricity by 2015.

The Solar Energy Grid Integration Systems program will continue soliciting project proposals from industry, with a goal of contributing $24 million toward $40 million worth of projects.

The first round of winners for potential funding are:

• Apollo Solar of Bethel, Connecticut


• EMTEC of Dayton, Ohio, with Emerson Network Power, Liebert Corp., Hull and Associates, and Ohio State University


• Enphase Energy Inc. of Petaluma, California


• General Electric of Niskayuna, New York, and Sentech, Inc., collaborating with candidate utilities including American Electric Power, Duke, and Hawaiian Electric Co.


• Nextek Power Systems of Detroit, Michigan and Hauppauge, New York, with Houston Advanced Research Center


• Petra Solar of Somerset, New Jersey, with Florida Power Electronics Center and Florida Solar Energy Center


• Premium Power of North Reading, Massachusetts


• Princeton Power Systems of Princeton, New Jersey, with TDI Power and World Water and Solar Technologies Corp.


• PV Powered of Bend, Oregon, with Portland General Electric Team, South Dakota State University and Northern Plains Power Technologies


• SmartSpark Energy Systems, Inc. of Champaign, Illinois, with Evergreen Solar and Innovolt, Inc.


• Florida Solar Energy Center of the University of Central Florida in Orlando, Florida, with SatCon, Sentech, Inc., EnFlex, SunEdison, Northern Plains Power Technologies, Lakeland Electric Utilities and other utilities


• VPT Inc. of Blacksburg, Virginia, with Center for Power Electronics, Plug-in Conversions, Moonlight Solar, Breakell Inc., and Delta Electronics

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