Published Feb. 16, 2010

Can a country produce too much solar electricity?

Yes, says CEPS, a company that manages the flow of electricity to customers in the Czech Republic, where solar is far more popular than it has been in the United States.

At a recent press conference, Petr Zeman, general director of CEPS, told reporters that the republic's grid may face overload problems unless solar installations are reined in or the grid's capacity is beefed up. Company officials also have cited problems in the past with wind-generated electricity while calling for increased investment in grid infrastructure. Some new grid tie-ins are being put on hold.

The Czech Republic has almost as much grid-tied solar-electric generating capacity as the state of California, but has a far smaller population. As a result, despite having much less average sunshine, the republic has more than triple the solar power capacity per person of California, the leading solar state in the U.S.

In the Czech Republic, as in many other European countries, solar owners are paid for producing electricity, receiving as much as the equivalent of 63 cents per kilowatt-hour. The production incentive, called a feed-in tariff, virtually guarantees an attractive investment return for solar owners.

In the U.S., rebates and tax credits are a more common form of incentive than the feed-in tariff common in Europe. Although these incentives in many cases make solar just as profitable an investment, if not more so, they have not prompted the rush to solar that has been occurring in parts of Europe.

There are similar feed-in tariff programs in the U.S., with more on the way. For example, Vermont, which has insolation levels roughly comparable to those of the Czech Republic, passed a feed-in law that took effect last fall, offering solar owners a rate of 30 cents per kwh. This rate is in addition to the federal 30 percent Investment Tax Credit available for solar equipment, meaning it is more competitive with the Czech Republic incentive than may appear.

Feed-in tariff proposals are under legislative debate in several other states.

In the Czech Republic, CEPS officials told reporters that the grid may be overloaded by solar producers as soon as the summer of 2011. They said the republic's solar incentive could increase solar capacity to 3,000 megawatts by 2012; the country had a solar production capacity of about 600 megawatts in 2009.

The company has been urging action to upgrade the utility grid for some time. Last fall, CEPS issued a news release saying that "wind farms in neighboring countries are threatening operation security of the Czech transmission system in the long term." The Czech Republic's electricity system is inter-tied with those of other European countries.

The company added that a long-term investment program was needed "to ensure the reliable operation of the Czech transmission system and to enable new generation sources to be connected to the grid."

The intermittency of solar electricity generation can pose problems for grid operators trying to seamlessly integrate the current flow with electricity generated from other power sources. Digital metering and distribution systems, now being installed by many utilities in the U.S., can help.

Conversion of vehicle fleets to electrification in large numbers also would allow grids to operate more efficiently. These vehicles' high-capacity batteries could be used to either store or dispense electricity when needed.  As in the U.S., plug-in vehicles are just beginning to be introduced in Europe.