DOE Funds Tests of Storage for a 30% Solar Arizona

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Preparing for a future when a third of us will make our own electricity from solar on our roofs and ship that power onto the shared grid – the U.S. Department of Energy has funded the development of a solar community in Flagstaff, Arizona to help test how well the grid can handle that.

With everything expected to be complete this month, the test is now ready to be switched on.

The DOE supplied a $3.3 million grant in 2010 to help Arizona Power Service (APS) set up the Community Power Project in the northern Arizona city to study the effects of a high concentration of solar rooftops on the grid.

APS, the oldest electricity utility in Arizona – and the owner of the largest coal power plant in the Southwest – must in turn run tests to see how well the grid can handle that much solar, spread out among individual customers, rather than coming from a single utility-scale project.

This Flagstaff neighborhood will have a distribution line that carries 30 percent solar energy, and “the question is: how do you optimize the grid in that case,” Dan Wool, spokesman for APS  told Energy Prospects West. This study “envisions a future when everyone has solar.” (Or one in three of us.)

Within the single Flagstaff neighborhood, APS has now installed photovoltaic systems on 125 residential rooftops ranging from 2 KW to 4 KW, along with solar water heaters in some low-income households and a 400 KW solar system at a local elementary school.

In addition to the small distributed rooftop solar arrays, about a third of the renewable energy for the Community Power Project will be generated from a 500 KW ground mounted solar farm consisting of PV panels arranged in several rows on top of single-axis tracking supports at the Doney Park Renewable Energy Site on 10 acres of land owned by APS.

To back up the solar energy and provide storage to even out the grid, APS included a 1.5 MWh battery storage system into the local grid at a substation.

“It enables us to even out stress on our system,” said APS engineer Joe Wilhelm.

Built by Canadian storage company Electrovaya, the storage consists of a collection of lithium ion batteries in a unit that “looks like a big shipping container,” Wool said.

Next year, APS will truck the Electrovaya battery system over to the Doney Park facility, where it will be used “to smooth out solar production,” according to Wool. “We’ll use it to test how to reduce wear-and-tear on the substation equipment caused by periods of high demand.”

“If a cloud comes along, we can dispatch battery power quickly to compensate for the drop in output,” he said. The next phases will be devoted to testing technologies, performance and business models and gathering results, Wool noted.

Even without renewable energy on the grid, small adjustments are constantly being made to ramp electricity up and down in line with supply and demand. That is because you can’t keep any extra electricity on the grid for later use. All electricity put on the grid must be taken off at the same rate, so if there is any excess, it must be taken out and stored.

But because we are beginning to add more renewable power to the grid, now there is one more reason to also add more storage for the grid.

All of the project’s renewable energy credits will go to APS to help it meet renewable energy standard requirements, that Arizona’s Republican legislature and its ALEC-led ACC is now working hard on dismantling, on behalf of coal powered utilities.

It will be instructive to see if this test by APS is in good faith and changes the coal/solar equation any in Arizona.

APS will own the panels and continue to charge the customers underneath for power, and makes no promises as to what happens in 20 years when the power contract is up.

As such, it is also a test for utility-owned distributed energy, which might turn out to be attractive to utilities, and thus ease the path to a climate friendly future.