Hurricane Sandy wiped out power to hundreds of thousands of homes in the Northeast, including electricity generated by solar panels. Most home solar systems don’t allow residents to live “off the grid” but instead act as part of it, sending excess power to the utility system during the day and pulling electricity back to run the house at night. When the grid fails, so do solar panels.
Experts and solar executives say smaller, more decentralized methods of generating and storing electricity help ease strain on the grid in times of high demand or failure. Adding batteries to a home system or using independent solar generators are two options available today. In a disaster, small charging stations can help residents charge cellphones or other electronic devices.
SolarCity is developing a battery backup system for its customers. Some battery systems enable solar panels to run a household directly during prolonged power failures. These are generally combined with battery storage sized for the home to provide 24-7 coverage. Requirements include a separate electrical panel and a complicated inverter that switches the flow of electricity entirely over to the house, according to Tony Clifford, chief executive of Standard Solar, an installer based in Maryland.
Adding battery storage to existing systems costs from $500 to $30,000, depending on the size of the panel system and how much of the house a customer wants to run. Demand for battery backup is not yet widespread, but the increase in storms and harsh weather, and a general strain on the power grid, may raise interest, says David Panico, senior vice president of the industrial power group at SunWize, a solar supplier that provided a low-cost mobile system to the Sandy relief effort.
One drawback of batteries is installation location, since flooding can be a consideration and water would render most systems unusable.
Electric vehicles could also provide a backup energy source. It’s possible for a car to fuel a house for days on a single charge. It’s not quite a practical option yet, even though the technology to make it so exists. The inverters required for a car to power a house are 50 to 100 percent more expensive than standard ones. Plus, since solar panels don’t always produce a steady stream of electricity, the average home solar array does not have sufficient strength to consistently charge a car.
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