Insight · September 28, 2026
Microgrid-ready design for critical facilities
Why feeder-level solar and storage are a planning tool for outages, public-safety shutoffs, and large loads that cannot stop.
A microgrid is an electrical system that can run on its own. It needs a source — solar, storage, or both — and a way to disconnect from the wider grid, called islanding. When the line is off, the local system can keep serving the loads it was designed for.
That matters most for facilities that do not get to pause: hospitals, water systems, cold storage, a school used as a shelter, a data hall with a backup requirement that diesel alone is a poor answer for.
The outage the design has to survive
California saw more than 57,000 wildfires from 2013 through 2019, about 8,000 a year. Utilities use Public Safety Power Shutoff events to de-energize lines in high-risk weather. In 2020 there were more than twenty such events. One California shutoff in 2019 was estimated at $2.5 billion in economic losses. The Caldor Fire burned more than 220,000 acres, destroyed 1,000 structures, and forced about 50,000 people to evacuate.
The transmission system those events are protecting is large — about 40,000 miles of lines in California — and lossy. Roughly 5% of electricity is lost moving across transmission and distribution, a waste the underlying analysis put at about $6 billion a year for U.S. consumers.
Local solar and storage do not replace that system. They shorten the distance between generation and the load that has to stay on.
Full feeder, partial feeder
For a utility, the useful version is often not a single-building backup. It is a project sited so it can support a whole feeder, or part of one, during a shutoff or a fault. Ranch Sereno (2.40 MWdc and 3.60 MWh, PG&E interconnection approved) was planned so it can support a Contra Costa County feeder that serves a school and a county facility.
The advisory work is the pairing, the interconnection, and the operating concept. It is not a claim that the practice builds or operates the microgrid.
What to decide early
- Which loads must stay on, and for how many hours.
- Whether the project exports, islands, or both.
- Whether a limited export profile would let it interconnect without a new line.
- Who calls the islanding sequence: the utility, the customer, or an automatic relay.
Those choices belong in the first study, not in a change order after the equipment is ordered.