National Grid USA subsidiary National Grid Green Homes Inc. is seeking the Federal Energy Regulatory Commission approval to acquire rights to participate in Sunrun Inc.'s grid services activities for the residential solar developer's rooftop solar generation facilities.
The deal also includes potential wholesale energy and capacity sales from the portion of an approximately 216.4-MW residential solar portfolio, a subset of Sunrun-owned rooftop solar generation facilities in which National Grid indirectly holds certain nonvoting securities, according to a July 5 regulatory filing.
National Grid, a subsidiary of U.K.-based National Grid PLC, in January 2017 invested $100 million in Sunrun's equity portfolio, as part of a broader partnership to explore how distributed energy resources such as rooftop solar panels can improve electric grid operations and be used in place of centralized power plants to keep the electric grid "balanced and optimized."
The equity portfolio consists of more than 28,000 residential solar systems, with approximately another 500 units expected to come online in the coming months. Some of the units are located in the PJM Interconnection, ISO New England, New York ISO and California ISO markets, while others are located in various nonindependent system operator/regional transmission organization areas.
While National Grid intends to provide grid services from only a small portion of the facilities in the portfolio, the company said it made a "conservative simplifying assumption" that it could use all of the generation in the portfolio for grid services because it cannot specify the exact portion of those facilities ahead of time.
The transaction comes as National Grid and other New York utilities are working through regulatory proceedings that are aimed at overhauling the state's retail electricity market. The New York State Public Service Commission is trying to redefine the role of utilities by making them "platform providers" charged with facilitating the widespread adoption of distributed energy resources.
National Grid is known legally as Niagara Mohawk Power Corp. in New York.