Quarry cuts power bill with solar, battery combo

COTATI — While solar electricity installations at businesses are increasingly common in the North Coast, Stony Point Rock Quarry's new photovoltaic array employs newer sun-following technology and is set to be augmented shortly with a cutting-edge battery system designed to shave the peaks off electricity use at full operation — spikes that have led to crushing power bills in the past two years.

In January, 33 20-foot-square articulating arrays of solar modules were fully operational on 2 acres of the quarry, located off Stony Point Road. The system is rated to produce less than 300 kilowatts. The AllSun Trackers motorized arrays are designed to capture as much as 45 percent more energy than stationary arrays by staying pointed at the sun throughout the day, according to manufacturer AllSun Renewables of Vermont.

"We sized the system to take care of the processing needs of this property," said Mark Soiland, president of Soland Co., which operates the quarry as well as Soils Plus in southern Sonoma County and Grab n' Grow near Santa Rosa.

A much larger solar system — 1.165 megawatts from 3,444 panels — was installed in 2011 at Mark West Quarry, run by BoDean Company, owned by Bo and Dean Soiland.By maximizing the energy production per square foot of land, Stony Point Rock Quarry plans to triple or quadruple the size of the solar field on available land over time, potentially plugging the excess energy into the newly operating Sonoma Clean Power agency, Mark Soiland said.

Yet the challenge is that the solar array handles typical operating demand for crushing rock and recycled concrete and sorting it into various products but not spikes in demand of up to 700 kilowatts. With changes to statewide electricity rates structure in past two years, those spikes sent the quarry's power bills spiking from $8,000 for months with full production to $25,000—$30,000 and as high as $33,000.

So to tap power that the solar field is producing to eliminate extra electricity needed from the grid at those peak operating times, the company took advantage of a grant through the California Solar Initiative to have a 200-kilowatt battery system, demand switch gear and service panel installed between the solar field and the grid delivery panel. The battery is set to arrive in July, Mr. Soiland said.

"Our solar array is sufficient for our needs, but the battery helps with peak demand," he said.

The battery comes from Tesla Motors of Emeryville in a 10-foot-square enclosure, he said. Tesla late last year announced a deal with SolarCity to package stationary storage systems with solar arrays for home use. Sources say that Tesla has been in talks with several North Coast wine producers about battery systems, and at least one vintner has projects about to start.

A Tesla spokeswoman declined to comment on the industrial battery program. In its regulatory filing and public comments, Tesla officials have said that stationary storage will be a major focus for the company in the next few years, including the planned battery production megaplex set to open in 2020.

The California Public Utilities Commission in 2011 eliminated the average rate limiter, so the commercial users such as the quarry were subject to penalties and charges and moved from the lowest rate of A6 on Pacific Gas & Electric's rate scale to the highest rate, E19, for grid demand peaks over 500 kilowatts in any two-month period.

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