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USF St. Petersburg developing solar battery to store power for homes

Imagine no fuel bill at all for your car — no gas, no added cost to your electric bill.

Or how about having the ability to keep your refrigerator running through the night after the power goes out, without using a gas generator.

Sounds like a dream. But it's more real than you might think.

A solar battery under development at the University of South Florida St. Petersburg aims to supply power to homes by collecting the sun's energy and storing it in a unit a little larger than the standard electric generator for sale at home-improvement stores. As the technology further develops, it could become a significant contributor to the overall power grid.

"This is among the leaders in actually testing and putting it to use," said Bob Gibson, a vice president of the Solar Electric Power Association, a nonprofit organization in Washington that works to help utilities develop solar technologies. "They definitely are helping to demonstrate that this technology does work."

Solar power's inability to generate electricity at night hampers its use as a primary energy source. A battery or some other storage system for the solar energy generated during the day would help strengthen the case for building more solar projects.

Other research focuses on different kinds of storage, such as compressed air, stored underground, or thermal storage, preserved in fluid.

"One of the challenges with renewable energy is that the energy is produced when the fuel source is available, not necessarily when the customer needs it most," said Tim Leljedal, a spokesman for Progress Energy. "In the future, energy storage could help manage the availability of electricity by storing excess energy during production and dispatching it when needed."

The joint venture between USF and Progress Energy, dubbed the Renewable Sustainable Electric Energy Delivery System — or SEEDS — is focused directly on that problem.

Here's how it works:

Researchers use 10 solar panels that look like an awning mounted across the top of a plant services building wall to collect the energy.

An electronic communication system carries that energy from the panels to the battery storage in a 10- by 4-foot storage shed that stands about 6 feet high with three compartments, all tucked behind a chain-link fence and hidden among bamboo plants beside the building.

The shed includes the battery and a control system.

When the researchers first built the battery and control system, it filled the entire shed. Now the equipment takes up just one of the three compartments and could fit in a small closet in a house.

The lithium ion battery has 15 cells that each last about an hour and can provide as much as 20 kilowatts of power — enough to power a refrigerator for 15 hours. A refrigerator is one of the top five energy users in a home, at a cost of about 25 cents a day.

Not only can the USF battery store solar energy, Progress Energy says it also can store electricity from other energy sources. The battery can sit charged for several months and lose just 2 to 3 percent of its energy.

The solar system pumps electricity into the regular power grid when it's not juicing up the battery.

Other features include the ability to communicate with the battery system from smart phones and tablets, a feature that would allow a person to turn on the battery from virtually anywhere in the world.

"Our challenge is to figure out how to make it more efficient . . . how to make the life longer," said Zhixin Miao, an assistant professor at USF who is working on the project.

A solar electric system that could take such items as the household refrigerator and an electric car off the utility grid would be a boon for consumers.

The Nissan Leaf, a new electric car, ranks as the second-highest energy user (air conditioning is No. 1 by far) in a home at a cost of 84 cents to as much as $2.80 a day, depending on usage. If motorists could use the car and then charge it at night with a battery charged from solar electricity, they could all but eliminate automobile fuel costs.

Besides working to make the battery more efficient, the other challenge is to make it cheaper.

The cost of solar electricity production in general remains high. Storage of solar energy isn't any less expensive.

Production costs and storage are two main reasons that even the state's and one of the nation's largest solar electricity producers, FPL, generates less than 1 percent of its electricity from solar.

The system developed at USF currently would run well up into the thousands of dollars for the complete system of energy generation and storage. Right now, the battery alone would cost about $6,000 — each of the 15 cells cost about $400. Those costs will likely drop as research continues.

Miao said the researchers are proposing to develop a full residential demo of the battery within two to three years that would be ready to market.

The Solar Electric Power Association's Gibson said the cost of such systems will be a factor in determining whether the battery becomes a significant player in energy in the home in the near future. He said he sees it more as a supplement than a primary energy supplier, but the project is raising hopes for increased use of alternative, clean energy.

"People have been hoping for breakthroughs in perfection and price," Gibson said. "This certainly has a lot of promise for extending the value of renewable energy."

Ivan Penn can be reached at or (727) 892-2332. Follow him on Twitter at and find the Consumer's Edge on Facebook.

USF St. Petersburg developing solar battery to store power for homes 06/25/11 [Last modified: Monday, June 27, 2011 9:29am]
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