Rolling Out Smart Inverters

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Utilities Use Different Strategies to Implement Grid Support Functions

Utilities are beginning to deploy autonomous grid support functions in smart inverters today, though some aspects of these rollouts face delays, according to an EPRI—Solar Electric Power Association (SEPA) white paper.

The widespread installation of solar photovoltaics (PV) in the United States has spurred utilities’ interest in smart inverters to help manage PV and enhance grid reliability.

The report profiles four utilities’ different approaches to implementing autonomous functions such as ride-through and voltage support. Hawaiian Electric and inverter manufacturer Enphase retrofitted thousands of PV systems with ride-through settings through a remote software update, while Arizona Public Service and Salt River Project are assessing new functions on a smaller scale through residential pilot programs. Pacific Gas and Electric’s deployment is based on compliance with California’s revised PV interconnection rules (Rule 21).

As utilities evaluate functions, they are delaying or limiting the deployment of expensive communications infrastructure needed to maximize their benefits.

Another insight in the paper: Deployment has been slowed because two important standards governing the safety, reliability, and electrical performance of distributed energy resources—UL 1741 and IEEE 1547—are being revised to incorporate smart inverter functions. In many cases, projects cannot be certified until these updates are final.

Artwork by Kirk Anderson