wiredinUSA May 2014

1,000-volt rooftop installations

With equipment available in Europe tested to 1,000 volts DC, regulatory authorities in the US are beginning to approve the components that allow 1,000-volt DC installations, as opposed to a previous 600-volt maximum. California-based Fresco Solar has just completed two rooftop installations using the newly available parts. One is a 102kw array on the roof of a nine-story office building in San Jose, and the other is a 440kw array on an industrial building in Hayward, CA. “The building departments of both cities confirmed that these are the first commercial thousand volt systems they have plan checked,” said Sean Kenny, CEO of Fresco Solar. “It was careful attention to the nuances of the National Electrical Code that saw us through, that

and the fact that we could show that the installations were only accessible to authorized personnel and not to the public.” The Hayward solar array uses over 15,000 feet of 1,000V PV wire. “This is half of what we would have needed at six hundred volts,” said Mark Jacobi, VP of operations for Fresco Solar. “And half the complexity. In both cases we passed inspection first time which is also a great reflection on our crews.” There are over 1,400 panels on the roof and 15 ABB Power One inverters. The San Jose installation also uses a distributed inverter strategy with four similar inverters. Only the small three-phase 480v AC, 1,000V DC inverters that meet US rules for grid interconnection make such projects possible.

wiredInUSA - May 2014 ire I - ay 2014

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