Princeton Satellite Systems is set to demonstrate an earthbound solar system that can power a home when the electric grid goes down, or even at night. The SunStation is designed to use lithium-ion batteries to provide reliable, albeit expensive, backup power.

Battery backup systems for solar power systems have been around for a long time. Jersey Solar, PSS’s partner in the SunStation venture, has installed systems that use the same lead-acid cells as car batteries. But lead-acid batteries provide a paltry amount of power compared to their high-tech cousins, lithium-ion batteries.

PSS is using more advanced batteries that can hold up to 14 kilowatt-hours of power, the equivalent of about 222 laptop batteries. That’s enough to run an energy efficient home’s appliances (minus power hogs like air conditioners) for days on end. In full sunlight, the batteries replenish in about two and a half hours.

Company vice president Stephanie Thomas says the SunStation will work when the power grid goes out, which, oddly, many older solar power systems cannot do. (Power companies once required solar systems that tied into the grid be rigged to shut down in case of a power outage because a utility worker could be shocked by the power coming from a solar-powered house. The new transfer switches disconnect the house from the power grid when it goes down.) What sets the SunStation apart from normal home arrays is the battery backup.

This kind of power doesn’t come cheap. A full system, including solar panels and the electrical work required, will cost about $50,000. A version with half the power will run $30,000. The company is set to demonstrate the system to the press on Friday, August 22, at the Meetinghouse Court home of PSS founder and CEO Michael Paluszek, who so far has the only working SunStation system.

“It’s still quite expensive,” Thomas says. “The premium that you as a homeowner or a business owner get is that it’s green and it’s off the grid.” Like any grid-tied solar power array, the SunStation can sell excess power back to the power company, paying for the solar panel cost with energy savings in about eight to 10 years. It’s also eligible for solar energy tax credits. Thomas believes the market for the SunStation is consumers who see the appeal of being entirely self-sufficient.

For example, gas-powered generators may not work in an emergency where gas lines are ruptured. In that case, the SunStation’s five Valence boat batteries kick in and keep the lights on. If the power comes back on even for a few minutes, the batteries can gorge on the temporary feast of power and recharge quickly. Thomas says there are also areas in Princeton where gas generators are not an option due to aging infrastructure.

“We do expect the cost to come down,” Thomas says. “Technology has come really far with lithium-ion batteries. If you try to put this system in five years from now, it will be a lot cheaper. This is still for early adopters.”

PSS also sells solar charging stations for early adopters of another kind of technology: electric cars. Its car charging station is a self-contained unit of solar panels and a battery that is capable of fully charging up an electric car in a matter of hours, as if it were plugged into a normal household electrical outlet.

That system also costs about $50,000. That price tag can’t compete with simply plugging a car into an existing outlet, but it has one major advantage: it can be deployed in remote locations, such as a large parking lot, without building any new infrastructure. Thomas says one potential client was the Princeton Plasma Physics Laboratory, which showed interest in installing a SunStation in its galaxy-sized parking tarmac on Interstellar Drive. The cost of digging a trench and running an electric cable out to the site would have been as much as the solar station, Thomas says, but the Department of Energy declined to fund the project.

For the home user, how long a house can remain powered depends on which appliances the homeowner connects to the batteries and how often they are used. Paluszek’s home is on the extreme end of the efficiency spectrum, with electricity-sipping LED lights and the latest, most efficient appliances. He charges a Nissan Leaf electric car and a Toyota Prius plug-in hybrid in his garage and runs his furnace with a low-speed 60 watt fan.

A normal house should be able to run lights, a refrigerator, and a heating system for days, according to Thomas.

On the other end are homes situated in flood zones. Thomas says one homeowner showed interest in the SunStation, but she advised against him getting it: his three sump pumps would drain the batteries in no time.

Another group of potential users for the SunStation is people who can’t evacuate during emergencies for one reason or another, and need to ride out storms in place but who still need power — for example, people with medical devices that need to be kept operating at all times.

“It’s green, it’s self-contained, there’s no maintenance, and there is a 10-year warranty on the batteries,” Thomas says. “This will help storm-proof your house.”

Princeton Satellite Systems, 6 Market Street, Suite 926, Plainsboro 08536; 609-275-9606; fax: 609-275-9609. Michael Paluszek, president. www.psatellite.com.

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