Grid ยท Analysis
The neighborhood built to island from day one
Treasure Island's redevelopment folded a microgrid into the plan. How it works, who owns it, and whether an older San Francisco block could ever do the same.
I. What islanding a neighborhood means
A microgrid (a section of the electric system that can run connected to the main grid or, when it has to, on its own) needs three things a normal block does not: some local generation, usually solar plus batteries; a set of switches that can cleanly cut the tie to the outside grid; and controls that hold voltage and frequency steady once that tie is open. Treasure Island's plans fold these into the buildout, with solar, battery storage, and distribution wiring laid so that priority loads can stay up when the cables under the bay go dark.
Islanding is not the same as running forever. A neighborhood microgrid sized for resilience typically aims to carry priority loads, water pumps, traffic signals, a community building, some homes, for hours or a day or two, not to replace the grid outright. How long it lasts depends on how much battery and solar sit on the island, how sunny the week has been (bay fog matters here more than almost anywhere), and how much load residents shed once the power goes local.
II. Who owns the wires out there
Power on Treasure Island does not come from PG&E. The San Francisco Public Utilities Commission serves the island through Hetch Hetchy Power, the city's own municipal utility, fed largely by hydroelectric generation from the Hetch Hetchy system in the Sierra. The redevelopment itself is overseen by the Treasure Island Development Authority, a city agency, with a private master developer building it out in phases across roughly two decades under the approved plan.
That ownership picture is most of why a microgrid was feasible here at all. When one public agency owns the generation, the wires, and the meter, it can plan storage and islanding switches as a single system, without negotiating across a utility boundary. On a typical San Francisco block the poles and wires belong to PG&E, many customers buy their supply through CleanPowerSF (the city's community choice program that sources cleaner power while PG&E still delivers it), and no single party controls the whole chain.
III. Whether a Victorian block could do the same
Porting the model to an older neighborhood runs into physical facts. A Victorian block has PG&E distribution already in the ground, limited roof area shaded by bay windows and cornices, and no obvious place to put a shared battery. Adding an islanding switch to an existing feeder means coordinating with PG&E and, in practice, a long interconnection and safety review. None of that is impossible, but none of it is cheap or fast, and honestly it may never pencil out block by block.
What does travel is the smaller version. A single building can island itself with rooftop solar and a battery. The city and the state have leaned toward resilience hubs, one hardened community building such as a library or rec center kept powered through an outage, rather than whole islanded neighborhoods. If you own your roof, the household version is available today; the neighborhood version is likely to stay rare, and mostly on sites like Treasure Island that get to start from bare fill.
IV. Worth watching this month
1. Treasure Island Development Authority board meetings, usually monthly, where phase schedules and infrastructure updates first appear; mostly routine, but the place any real milestone shows up.
2. SFPUC and Hetch Hetchy Power planning and rate documents for any mention of island storage or microgrid sizing, which would tell you how large the local backup is meant to be.
3. The California Public Utilities Commission's microgrid and resiliency proceedings, which set the statewide rules any PG&E-side neighborhood microgrid would have to follow; slow-moving but decisive.
4. California Energy Commission microgrid grant rounds, which occasionally fund community projects and show where public money is going.
5. California ISO notices on how local resources connect to the wider grid, technical and rarely urgent, but the backdrop for all of it.
Frequently asked questions
Does Treasure Island already run on its own microgrid today?
Not fully. Much of the island still draws power through cables from the mainland, and the islanding capability is being built in as the redevelopment proceeds, so treat any claim that it is finished with caution.
Is my power on Treasure Island from PG&E?
No. The SFPUC serves the island through Hetch Hetchy Power, the city's municipal utility, which is different from most of the rest of San Francisco.
Could my own house island during an outage?
A house with rooftop solar and a battery configured for backup can keep some circuits running when the grid is down. Plain grid-tied solar without a battery usually shuts off in an outage for safety reasons.
Why does fog matter for a solar microgrid here?
Fog cuts how much a battery can recharge, especially in summer along the western and bayfront neighborhoods. A fog-prone site needs more storage to ride through the same outage than a sunny inland one would.
References
- Treasure Island Development Authority, City agency overseeing the redevelopment; board agendas and plan documents., sftreasureisland.org.
- SFPUC Hetch Hetchy Power, The municipal utility that serves the island; service area and planning information., www.sfpuc.org.
- CleanPowerSF, The city's community choice program, for how supply works on a typical block., www.cleanpowersf.org.
- California ISO, Grid operator for most of California; how local resources tie into the wider grid., www.caiso.com.
- California Energy Commission, State energy agency (.gov); microgrid programs and grant rounds., www.energy.ca.gov.
- California Public Utilities Commission, State regulator (.gov); microgrid and resiliency proceedings that set the rules., www.cpuc.ca.gov.