Industry petitions U.S. to ease grid limits

The Solar Energy Industries Association (SEIA) is sending a petition today to federal regulators proposing a solution to a standard that has limited the amount of solar power that can be added to homes in booming regions like California, Hawaii and New Jersey.

These states have seen solar panels, boosted by falling prices and generous subsidies, bloom on rooftops at a record pace. The surge has come so quickly, in fact, that sections of the grid have run into what's known as the 15 percent rule, a standard that has effectively capped rooftop solar installations, frustrating consumers and retailers alike.

SEIA's petition, filed with the Federal Energy Regulatory Commission, would supplement the 15 percent rule with screens specific to solar power. These screens would allow rooftop solar panels to be added to the grid at a higher rate, eventually limited to matching the minimum amount of electricity present during peak daytime hours.

The commission's provisions, which are emulated by state regulators across the country, have "become unduly discriminatory and unreasonable barriers to solar market access due to changes in circumstances, in particular the dramatic growth of the solar power market," SEIA wrote in its petition.

"It is essential that regulatory barriers that limit development be removed to allow companies that are developing solar projects to have access to electricity markets,” said Rhone Resch, SEIA’s president. “SEIA is proactively engaging FERC to find a regulatory balance that maintains grid safety and reliability and facilitates fast track interconnection of wholesale distributed generation."


The 15 percent rule has its origins in attempts to foster worker safety and prevent grid disruption. Typically, it triggers expensive studies if the amount of decentralized generation on the grid -- be it solar panels, a diesel generator or anything else -- exceeds 15 percent of the maximum daily load. The threshold itself stems from an engineer's rule of thumb, but it has become a traditional standard in the industry.

For several years, however, researchers have said the threshold, when applied to solar power -- which operates only during the day, when electricity demands are at their peak -- may be too conservative. And the case for updating the rule has been bolstered recently by a report released last month by the Energy Department's National Renewable Energy Laboratory (NREL).

The study took a close look at the 15 percent threshold and found that, when it comes to rooftop solar, the limit could and should be raised, recommending a screen identical to SEIA's proposal. Many circuits have surpassed the 15 percent threshold, the report's authors noted. Even in these regions, the safety, performance and reliability of the grid have not been deeply changed.

Unless it is changed, the 15 percent rule will become more and more a problem, said Ben Kroposki, an NREL expert on rooftop solar and an author on the study, in a recent interview.

"They have to address this now," he said. "They can't wait. Because this is holding up deployment."

It is uncertain how quickly FERC could act on the petition. And, typically, the 15 percent rule stems from state regulators, several of which have been struggling to come to terms with their rapid solar growth. SEIA hopes its proposal, then, could also serve as a guide for these regulators.

Click here for more about the 15 percent rule.

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