Distributed Energy Resources

Association’s Zummo outlines reasons why grid defection unlikely

Weather patterns, economics and technical considerations are all factors that come into play that collectively minimize the likelihood of complete grid defection in the U.S., said Paul Zummo, director of policy research and analysis at the Association, on Nov. 12.

He made his comments on the first day of the Association’s Public Power Forward Summit in Austin, Texas.

In July, the Association released a report, the Value of the Grid, which said that as more people install solar and storage systems in their homes, and even with declining prices in these technologies, staying connected to the electric grid remains a more economical and practical option for customers.

The paper concludes that complete grid defection is not likely for a number of reasons, Zummo noted in his remarks at the summit, including technical considerations.

Not everyone owns their own home, and for those that do, not every house is available for solar photovoltaics due to limited roof space, “so there’s a limitation of how much PV is available for solar rooftop,” he said.

He also cited the “Cleveland effect,” which refers to weather impacts and the “you don’t live in Southern California or Arizona” effect. There is not enough sunlight throughout the year “to power your homes constantly, even with battery storage.”

Economics also comes into play. Zummo pointed out that the typical U.S. electric bill is around $114 per month. To place solar panels on a roof, even with the price decline for solar, along with “probably two Tesla Powerwalls” in order to have sufficient storage, “we’re looking at an investment in the neighborhood of around $30,000 to be completely self-sufficient. That comes out to three or four hundred dollars a month, compared to what most people are currently paying,” the Association official said.

While the economics will change, “When you add in the weather considerations, the technical considerations, going completely off the grid is not likely,” he said. “That doesn’t mean, though, that folks are not going to rely more and more on DERs and that’s certainly going to have an impact.”


With respect to rates, Zummo told the audience of public power officials that “certainly, we’re going to have to change our rate design so that we can fully fund” new business models.

He said that time-of-use rates are becoming a lot more prevalent. California public power utility SMUD is rolling out its default time of use rates, along with the state’s investor-owned utilities.

“Several other public power utilities are also rolling out time of use rates,” Zummo said.

“I’m not sure about performance-based rates. I don’t know how applicable they are to the public power model. That’s certainly an option,” he said.

For more information about rate design options and how they affect customers and utilities managing distributed energy resources, see Distributed Energy Resources and Public Power, a report from the  Association.