PowerSwitch

800,000 Microinverters Remotely Retrofitted on Oahu—in One Day

Utilities are asking more of the rooftop solar systems that increasingly are popping up throughout their distribition grids. As we profile in this month’s Spectrum, leading utilities are deputizing solar system’s inverters to function as junior grid regulators to help stabilize the grid. Hawaiian Electric Company and inverter manufacturer Enphase Energy just showed how swiftly such upgrades can happen.

In a single day Enphase and HECO remotely reprogrammed some 800,000 microinverters attached to individual photovoltaic panels on Oahu, accounting for roughly 60 percent of the island’s distributed solar capacity according to Ameet Konkar, Enphase Energy’s senior director for strategic initiatives. Those systems deliver up to 140 megawatts, nearly as much power as the state’s largest conventional power plant, says Konkar.

Oahu needs higher-functioning solar systems because it leads the U.S. in per capita solar penetration, with 12 percent of residential customers operating rooftop systems. Island grids are more susceptible to even small perturbations, such as occurs when trees fall on wires and lightning strikes. The solar upgrade will help HECO’s grid ride through the resulting power glitches.

Whereas standards required solar systems to shut down at the first sign of substandard AC voltage and frequency, HECO and Enphase’s upgrade instructs the PV microinverters to ride through such irregularities. Like the momentum in a conventional power plant’s spinning turbines, the solar systems’ enduring power generation should help restabilize the grid’s AC signal.

Firstly, tens of millions of dollars of expense were avoided which will implicitly avoid that cost needing to be passed on to customers. So Enphase theoretically just helped to keep the operating cost of the networks down, and the retail price of electricity too.

Secondly, although materiality is unclear at this point, by riding through more events rather than shutting down at the whiff of a drift in frequency, 800,000 solar inverters will be on-line for more time. That delivers better yield and more savings for consumers and in the case of Hawaii, less oil burned for conventional generation. So they just made more money for their customers.

Third, Enphase’s clever little solution saved the network a whole lot of money, because they had the data, the tools and the technology handed to them on a platter by someone else, which improved the reliability of their network asset.

This is an example of simple, effective and rapid collaboration with real benefits that spread across the entire value chain.