North Carolina approves Duke's first solar+storage residential microgrid

UPDATE: May 22, 2019: This story was updated to include a link to, and information from the North Carolina Utilities Commission's final order.

Dive Brief:

North Carolina regulators on Friday approved a solar+storage microgrid project proposed by Duke Energy, designed to help maintain reliable power for a small town called Hot Springs in the western part of the state.
The project includes a 2 MW solar array and 4 MW lithium-ion battery, and will be Duke's first utility-scale solar+storage project for residential customers.
The microgrid is a small part of Duke's broader plan to roll out more storage on its system. The utility expects to spend $500 million on battery storage in the next 15 years and plans to wrap up construction on a 9 MW storage project in Asheville, North Carolina by the end of 2019, according to company spokesperson Randy Wheeless.

Dive Insight:

Hot Springs is served by a single 10-mile transmission line that passes through mountainous terrain in the Pisgah National Forest, creating frequent, lengthy outages. Whether Duke's microgrid is the cheapest way to address the problem remains an open question, but regulators say the project could give the state and utility a better understanding of how the storage technologies can make the grid more reliable.

"Though it is not clear that the Hot Springs Microgrid is the most cost effective way to address reliability and service quality issues at Hot Springs, the overall public convenience and necessity would be served by granting the certificate," the Utilities Commission concluded in their order.

The system benefits from the Hot Springs Microgrid are material, "but are difficult to quantify accurately without real world experience in [Duke's] service territory," the North Carolina Utilities Commission wrote. Regulators said Duke will "gain valuable experience" by operating the microgrid, "and this experience and data collection and analysis will be beneficial in future cost-benefit analyses of projects with that proposed to include an energy storage component."

The Hot Springs microgrid will be capable of islanding from Duke's system, but while grid-tied, it can also provide essential reliability services such as frequency and voltage regulation, ramping support and capacity during system peaks.

In its order, the North Carolina Utilities Commission concluded that "because of the unique needs of the Hot Springs service area, exploring the wholesale market for the capacity and energy to serve those needs is not feasible."