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

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

Solar ยท Analysis

The East Shore's silver roofs, added up

From Oakland to Richmond, the bay's flat industrial roofs are its biggest unused solar surface. Whether they get covered comes down to the wire under the street, the price for exported power, and who does the wiring.

Filed October 10, 2026 By the Clean Energy SF editors Reading time: 6 minutes

I. How a big-roof deal gets signed

Most warehouse owners don't install solar themselves. A rooftop developer leases the roof (basically renting the sunlit surface) or signs a power purchase agreement (a PPA, where the building buys the solar power at a set rate instead of owning the panels), which keeps the upfront cost and the paperwork off the owner's books. That is why a single real estate company can hold dozens of East Shore roofs and still not have a panel on any of them: the deal waits on the developer, the lender, and the grid.

Before any panel goes up, the developer files to connect under PG&E's Rule 21 (California's tariff setting how a private generator ties into the utility's distribution grid). That study decides whether the local line needs upgrades, and it sets the clock. If you lease space in one of those buildings, the delay you feel is usually this interconnection queue, which can run many months and sometimes longer when the feeder is crowded.

II. The honest math, after the 2023 rule change

Economics shifted in April 2023, when California moved commercial and residential customers to the Net Billing Tariff (often called NEM 3.0), which cut what the grid pays for solar power sent back to it. For a warehouse that uses most of its own power in daylight, refrigeration, forklift charging, machinery, on-site use still pencils out, because every kilowatt-hour made and used on the roof is one not bought from the utility. For a roof built mainly to export, the return got thinner, and the honest word on any given building is that it depends on the load underneath.

III. The grid's quiet veto

Hosting capacity is the other gate, and often the harder one. PG&E publishes an Integration Capacity Analysis map (a public map showing roughly how much new generation each distribution line can take before it needs costly upgrades), and some East Shore feeders near old industrial substations are already tight. A perfect roof on a crowded line can still be told to wait.

This is where the add-it-up framing meets reality. The East Shore holds hundreds of large flat roofs, but they do not share one wire; each sits on a feeder with its own limit, so the region's real potential is the sum of many small local answers, not one big one. When a developer passes on a roof, it is often the line under the street, not the roof, that said no.

IV. Who is at the table, and who wires it

Several parties share the deal: the building owner, the rooftop developer, PG&E as the wires company, and the community choice aggregator that buys the power. Oakland and most of Alameda County are served by Ava Community Energy (formerly East Bay Community Energy), while Richmond buys through MCE (Marin Clean Energy). Both are community choice aggregators, public agencies that purchase electricity for residents and businesses while PG&E still owns and runs the poles and wires.

Installation is local work, and that is much of the point. The crews are electricians, often IBEW, and larger projects on public or leased public land can trigger prevailing wage rules that hold pay up. California's solar workforce runs into the tens of thousands statewide at last public count, and a warehouse-roof build-out across the East Shore is one of the few clean-energy projects that puts those jobs on this side of the bay rather than in the desert.

V. Worth watching this month

1. PG&E's Integration Capacity Analysis map updates on a schedule; watch for a refresh showing more or less room on East Shore feeders near the Port of Oakland and Richmond (this one genuinely moves which roofs are viable).

2. CPUC proceedings on the Net Billing Tariff and its successor rules continue; watch for any decision touching commercial export rates, because that reaches straight into roof economics.

3. Ava Community Energy and MCE post board agendas monthly; watch for new commercial or local build-out programs (mostly routine, occasionally substantive).

4. The Oakland Army Base and Port redevelopment areas periodically issue solar or microgrid solicitations; watch for a request for proposals.

5. CAISO's annual transmission and interconnection planning can shift what smaller distribution projects face downstream; watch for its planning cycle updates (routine, but worth a glance).

Frequently asked questions

Can I put solar on my own warehouse without a developer?

Yes, if you own the building and have the capital. Many owners instead lease the roof or sign a PPA so the developer carries the cost and handles the interconnection paperwork.

Why does the grid sometimes say no?

Each distribution line can absorb only so much new power. If your feeder is near that limit, the utility may require upgrades that take time and money, which can stall or shrink a project.

Did the 2023 rule change kill warehouse solar?

No, but it changed the math. Roofs over buildings that use most of their power on site still pencil out, while roofs built mainly to export earn less for that power than they used to.

Who actually buys the power?

In most of the East Bay it is a community choice aggregator, Ava Community Energy in Oakland and much of Alameda County, and MCE in Richmond. PG&E still delivers the electricity over its wires.

References