Last week, the University of Arizona and Tucson Electric Power Co. marked completion of a new energy-storage system and solar array built by E.On North America at The Solar Zone at the UA Tech Park.

But it was more of a new beginning than an end for the 223-acre Solar Zone, which the UA rightly touts as one of the largest multi-technology renewable-energy demonstration sites in the world.

E.On’s Iron Horse Energy Storage and Solar Project is actually the first project for phase two of The Solar Zone on the northwest side of the UA Tech Park.

Iron Horse, which consists of a 10-megawatt capacity lithium-ion battery-storage facility and an accompanying 2-megawatt photovoltaic array, is also the first North American energy storage project for E.On, which is part of a German-based company that is one of Europe’s biggest electric utilities.

Bruce Wright, UA associate vice president of Tech Parks Arizona, said that by Labor Day, the UA will issue a formal call for new projects for phase two of The Solar Zone, but not for new solar arrays.

The phase-two projects will focus on energy storage; grid optimization and microgrids; distributed solar systems; and integrated and embedded solar materials.

“This is an effort to move into some new areas of solar technology development and research,” Wright said, adding that Tech Parks will court potential partners globally including Germany, Finland and Israel.

The UA also is exploring the use of solar energy in mining, agriculture, and defense and security systems, and the second phase of The Solar Zone includes plans for a solar education and visitor center.

Wright said the Tech Park is preparing a report on the performance of the Solar Zone installations, which host 10 companies and solar installations with a generating capacity of 25 megawatts — enough to power some 4,600 TEP homes.

Most of the projects planned for The Solar Zone came to fruition, with the exception of a 5MW thermal solar installation planned by the now-defunct Bell Independent Power Corp., which was replaced by other installations.

TEP buys the power from the Solar Zone installations under various power-purchase agreements.

The cost of power from the new E.On array is just 3 cents per kilowatt-hour — which TEP says is its lowest-cost renewable power deal yet, and perhaps one of the cheapest in the nation, according to solar-industry observers.

The cost of stored energy adds about 1.5 cents, but even with that cost it’s still far cheaper than the 10 to 12 cents TEP was paying on renewable-energy power contracts just a few years ago.

TEP will soon bid out 70MW of new energy storage, as part of a larger plan to add even more utility-scale renewables to reach about a third of its overall power generation portfolio, said Carmine Tilghman, TEP senior director of energy supply and renewable energy.

The E.On storage system mainly will be used for ancillary energy services, like frequency regulation and voltage control, which will help TEP make its power grid more resilient and reliable, said Mark Frigo, an E.On vice president for North American storage.

But TEP also plans to buy long-duration storage systems that can store power generated by photovoltaic systems for use when the sun goes down, Tilghman said.

“Projects like this are going to allow us to integrate even more renewables, and bigger projects, to allow us to move away from fossil fuels,” he said Thursday at a dedication event for the new E.On installations.

E.On has partnered with TEP on three other solar projects: a separate, 6MW photovoltaic array at the Solar Zone; a 13MW installation near East Valencia and South Craycroft roads; and a 17MW system at Fort Huachuca in Sierra Vista.

E.On is all in with TEP’s vision for energy storage, said Steve Trenholm, president of E.On Solar Energy and Storage.

The company is building two more energy-storage systems attached to E.On wind-energy projects in Texas that are slated to come online by the end of this year.

“We believe this is where the future of energy is going — this is the new energy world,” Trenholm said at Thursday’s dedication event.

Tucson Tech runs Thursdays or Sundays in the Star. Contact senior reporter David Wichner at dwichner@tucson.com or 573-4181. On Twitter: @dwichner

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