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

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

Grid ยท Analysis

Oakland's school buses could power the grid between runs

A yard full of electric school buses in Oakland can push power back to PG&E on hot afternoons. The open questions are how much that is worth and who gets paid.

Filed October 21, 2026 By the Clean Energy SF editors Reading time: 6 minutes

I. How a parked bus feeds the grid

If you pay an electric bill in San Francisco, the tightest hours on the grid tend to land on the warm, clear evenings when the fog stays out past the Sunset and the inland valleys bake. That is when power costs the most and the system has the least room to spare. Across the bay in Oakland, a few dozen electric school buses sit parked in a yard through those same hours, batteries mostly full, waiting for the afternoon route.

Oakland Unified runs one of the larger electric school bus fleets in the country, on the order of six dozen buses at last public report, and many are wired for what the industry calls vehicle-to-grid charging (a setup where the bus can push power back out of its battery and onto the utility's wires, not just pull power in). A vehicle-to-grid bus needs three things the ordinary electric bus does not: a charger that runs in both directions, a utility agreement that lets power flow backward, and a schedule that lines up the bus's idle hours with the grid's hungry ones. The first is hardware, the second is paperwork with PG&E, and the third is the hard part, because a school bus exists to move children, and the route always wins.

II. The honest math on a hot afternoon

California's grid operator, CAISO (the California Independent System Operator, which balances supply and demand across most of the state), sees its steepest demand on summer evenings as air conditioning runs and the solar on the system fades. A bus yard that can discharge from roughly 4 to 8 p.m. is aiming at exactly that window. One bus carries a battery on the order of 100 to 150 kilowatt-hours, so a lot of fifty buses is, in round numbers, a few megawatt-hours of stored energy, give or take, assuming the batteries are full and the drivers do not need them first.

On an ordinary day a megawatt-hour is worth a modest number. During a grid emergency, when CAISO issues a Flex Alert (a public call to cut usage during tight evening hours), the value of not needing that power climbs fast. Genuine emergencies are rare, maybe a handful of afternoons a year, and the buses have to be charged and available on exactly those days to matter. Every discharge also ages a battery a little, so the programs that pay for vehicle-to-grid have to cover that wear and still leave something over, or the district is quietly subsidizing the grid.

III. Who collects the value

Follow the money and you find at least four hands. The California Energy Commission (the state agency that funds clean transportation and files its grants publicly) has helped pay for buses and chargers. PG&E sets the terms under which power flows back. A fleet operator, the company that runs the buses day to day, manages the charging. And the district owns the buses and answers to parents.

Each party wants a share of whatever the idle batteries earn, and the split is not settled. If the grid value is real, the open question for an Oakland or San Francisco ratepayer is whether it lands as lower bills, as a payment to the district that eases a school budget, or as margin for a contractor. You can read the direction of that answer in the grant filings and the pilot terms, which are public and worth checking before anyone's press release tells you what to think.

IV. Worth watching this month

1. Watch the California Energy Commission's clean transportation grant pages for new or amended awards tied to Oakland Unified's fleet, which would signal how the next round of buses and chargers gets paid for.

2. Watch PG&E's bidirectional and vehicle-to-everything charging program pages for updated pilot terms, since the rate a bus earns for exporting power is close to the whole question.

3. Watch CAISO's summer assessment and any Flex Alerts, because the value of a parked bus battery is highest on exactly the evenings the operator warns about.

4. Watch the Oakland Unified board agendas for fleet and transportation contracts, which is where the split of any grid revenue would show up in public.

5. Watch the California Public Utilities Commission's transportation electrification proceedings, routine for now, for rules on who may sell power back and at what price.

Frequently asked questions

Does Oakland Unified actually send power back to the grid today, or is this a plan?

The buses and bidirectional chargers are real and in use, and the district has run vehicle-to-grid demonstrations. How routinely power flows back, and on how many buses, is best checked in the district's and the fleet operator's current records.

Would this lower my PG&E bill in San Francisco?

Not directly, and not much on its own. The value of one bus yard discharging on peak days is small next to the whole region's demand, though many such resources together can ease system costs over time.

Why school buses and not regular cars?

School buses sit idle for long, predictable stretches in the middle of the day and park in one known lot. That makes them far easier to schedule and wire than scattered personal cars.

What is the catch?

Discharging ages the battery, and the bus must always be ready for its route first. The programs have to pay enough to cover that wear, or the district loses money helping the grid.

References