Clean Energy SF: San Francisco, fog then sun, est. 2026

Vol. 1 - No. 14 - Thursday, September 24, 2026 - Free to readers

Grid ยท Analysis

The ridge that keeps its lights when PG&E cuts the power

On the San Mateo coast ridge, where PG&E's planned shutoffs go dark first, the state is testing whether to cut the end of a long line loose and run it on local solar and batteries. Here is how that works, and who decides.

Filed November 7, 2026 By the Clean Energy SF editors Reading time: 6 minutes

I. How islanding a neighborhood actually works

Two related ideas are on the table, and they are not the same. A remote grid (PG&E's term for permanently disconnecting a small group of customers and powering them with standalone solar, batteries, and a backup generator) suits a handful of meters at the literal end of a line. A community microgrid keeps the normal grid connection but adds local generation and a switch, so the neighborhood can island, meaning disconnect and run on its own, when the larger grid is down, then reconnect when it returns.

Here the coast does something odd to the math. Rooftop solar on the ridge works, but the summer fog that defines Pacifica and the Montara coast can hold on for days, so a microgrid built for a multi-day October shutoff has to be sized for weather, not just for a sunny afternoon. That usually means more battery storage and a fuel backup than a desert town would need, which is part of why these projects pencil out slowly and why each one gets studied on its own.

II. What it costs, and who carries it

Remote grids and community microgrids are not cheap, and the bill does not vanish just because the poles come down. PG&E has said a standalone remote grid can be cheaper than rebuilding and maintaining a long, fire-prone line to serve only a few customers, which is the whole premise. The savings, if they are real, show up over decades, and the upfront cost lands first.

For a ratepayer, the honest answer is it depends on how the CPUC (the California Public Utilities Commission, the state regulator that approves what utilities may charge) treats the spending. Some costs are spread across all customers as a resilience investment; some are expected to be offset by the line maintenance the utility no longer has to do. At last public report the accounting is still being argued case by case, so anyone who tells you the exact effect on your bill is guessing.

III. Who decides when the island runs

The rules come from a 2018 state law, Senate Bill 1339, which told the CPUC to make it easier to build microgrids and to work out how they connect, who is liable, and how they are paid for. That work lives in an open CPUC microgrids proceeding, where the commission, PG&E, and groups like community choice providers file positions. CleanPowerSF, San Francisco's public power program, is a community choice aggregator, so the city has a seat at that kind of table even when a project sits down the Peninsula.

On the ground, the harder questions are operational. Who flips the switch to island, the utility's control center or a local operator? How long can the neighborhood run alone before the batteries need the sun or the generator needs fuel, and when does it reconnect? Those answers are written into each project's design and its interconnection agreement, not set once for the whole state, which is why reading one filing tells you about one ridge, not all of them.

IV. Worth watching this month

1. The CPUC microgrids proceeding, where PG&E files its Remote Grid and Community Microgrid Enablement updates, for any new coast-side site on the list (routine docket traffic, worth a glance rather than alarm).

2. PG&E's PSPS forecasts and the National Weather Service fire-weather watches as the offshore wind season runs into late fall, since those are what trigger the outages a microgrid is meant to cover.

3. PG&E's Remote Grid program page for named locations, since the utility tends to announce specific sites as they move from study toward construction.

4. The CPUC fire-threat map and any changes to high fire-threat district boundaries on the San Mateo ridge, which quietly shape where these projects are even eligible.

5. CleanPowerSF and SFPUC board agendas for mentions of resilience or microgrid pilots, a signal of whether San Francisco itself is pursuing the same idea inside the city (early and speculative for now).

Frequently asked questions

Will a microgrid keep my lights on during the next shutoff?

Only if you sit inside a built project's boundary, and most of the coast is not there yet. These are a handful of sites at the study or pilot stage, so for now a home battery or generator is the reliable personal backup.

What is the difference between a remote grid and a community microgrid?

A remote grid permanently cuts a few customers off the main line and powers them locally for good. A community microgrid keeps the grid connection and only islands when the larger grid goes down, then reconnects.

Does running on solar and batteries work through coast fog?

It can, but fog means the system leans on stored energy and a backup for longer, so these projects are sized with extra battery and fuel. That raises the cost and is one reason each one is studied carefully.

Where can I check this myself?

The CPUC microgrids pages and PG&E's Remote Grid and Community Microgrid Enablement pages are public. They list the program rules and, as projects advance, the specific locations involved.

References