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Assembly in Minnesota
Silent Power has developed circuitry to control and convert power. It relies on batteries from other manufacturers. The units are assembled in Baxter, 130 miles northwest of the Twin Cities. Frederick said the company mainly uses lead-acid batteries, though units with higher-storage lithium-ion batteries also can be ordered.
Early on, the company sold its batteries for cabins and other uses off the grid, he said. But that market was small, so Silent Power targeted other applications, including backup power, solar arrays and demand management.
Battery storage investments can benefit from a 30 percent federal tax credit when installed with solar arrays, Frederick said. The state’s first community-owned solar array planned in Rockford plans to use Silent Power technology and take advantage of the tax credit.
On a price-per-kilowatt basis, the technology faces tough competition from generated electricity, especially power plants fueled by natural gas that often are used to meet peak demand. After a 2009-2011 analysis of its grid-scale storage battery in Luverne, Xcel concluded that battery prices need to drop before that method of storage makes economic sense.
Battery storage for the grid is being broadly studied under a $185 million Energy Department program funded under the federal stimulus law.
The four Minnesota co-ops received $300,000 under the program to purchase and test small-scale storage, and chose the Silent Power technology, Hentges said. One study participant, Wright-Hennepin Cooperative Electric Association, is an investor in Silent Power.
Christopher LaForge of Port Wing, Wis., who installs solar and battery systems and trains others to do it, said battery storage for businesses to reduce their demand-related utility charges can take more than five years to pay off, which is too long for many companies.
Customers with computer or medical equipment may be willing to pay for uninterrupted electrical service using backup batteries, he said.
“If you hate any power outage, the payback is instant,” LaForge added.
David Shaffer • 612-673-7090 Twitter: @ShafferStrib