Solar Shuts Down When Most Needed
Hurricane Sandy and its resulting economic losses have motivated a variety of stakeholders in New York City to come up with new ideas for back-up power during emergencies.
At the seventh annual NYC Solar Summit this week, power executives pointed out that solar installations in urban areas are generally grid-tied and designed to shut down when the grid fails so as not to feed power onto downed lines.
The inverters on solar systems are designed to shut down when there’s a problem with the grid because “you can’t have live power coming down a line that a lineman is working on,” explained Laurie Reilly, a spokeswoman with the City University of New York (CUNY).
A technical panel at the NYC Solar Summit yesterday presented on resiliency and the capability of solar to supply power in emergencies such as Sandy. The panel discussed new technologies that re-route the power captured on rooftops by solar and other distributed generation, allowing these resources to contribute during disasters.
One of the panelists, Tristan Kreager, manager of hybrid energy solutions with SMA America, said one of the company’s Sunny Boy residential inverters can provide a secure power supply of up to 1500 watts from the PV plant during grid failure. “There’s logic inside the inverter that registers when the utility is down and prevents any backflow of power onto the grid,” said Kreager. The inverter then isolates any power from the PV system to an accessory port, allowing for an AC circuit. The AC circuit only becomes alive during a grid outage and it needs to be manually switched on. The AC circuit can then be used to plug in household devices up to 12 amps such as appliances and cell phones, for example.
In January, CUNY formed the Smart Distributed Generation Hub with federal, state and city collaboration, working together to implement changes that can help utilize not only solar power, but other distributed generation solutions as resilient resources during emergencies.
Earlier this year, Green Power Resource Management (GPRM) announced production of its non-grid-tied solar powered air conditioner and virtual power plant in its new manufacturing facility in Escondido, Calif. “Typical solar installations are grid-tied and do not provide power when the grid goes down, said Ralph Ciarlanti, GPRM CFO. “Most customers do not know this.” Ciarlanti explained that the solar modules themselves are often powered by AC power coming in from the grid via a switching device at the master panel. It’s somewhat ironic that solar panels can generate electricity, but often need a little grid power to operate.
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