Until very recently solar contractors in the USA were restricted to 600 Volts maximum, but equipment has long been available in Europe that is tested to 1000 Volts DC. Now regulatory authorities are starting to approve all the components needed to build commercial solar installations at this higher voltage.
Fresco Solar, a California solar contractor best known for designing and installing photovoltaic systems on new public works buildings, has just completed two rooftop installations using the newly available parts. One is a 102 Kilowatt array on the roof of a nine story office building in downtown San Jose, CA, and the other is a 440 Kilowatt 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, “and 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 fifteen thousand feet of 1000 Volt 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 1400 panels on the roof and fifteen ABB Power One inverters. The San Jose installation also uses a distributed inverter strategy with four similar inverters. In fact, the availability of small three phase 480 Volt AC, 1000 Volt DC inverters that meet U.S. rules for grid interconnection was the key to all of this.
“Panels and inverters are commodities,” adds Kenny, “so the only real differentiator we have is installation cost. This move saves us a lot of labor, wire, connectors, combiners. We have already redesigned two projects on the books and are bidding all of our projects based on this new reality.”
With declining incentives and tariff wars starting to drive panel costs up again the U.S. solar industry needs this kind of innovation to sustain the growth of recent years.