Multifamily Solar in California: VNEM, SOMAH, and Title 24

The split-incentive problem, and why it's the whole story here

A single-family homeowner who installs solar pays for the system and receives the utility bill savings directly. An apartment building doesn't work that way. The owner capitalizes the roof, the inverter, and the interconnection; the tenants hold the individual electric accounts and pay PG&E, SCE, or SDG&E directly every month. If there's no way to route the solar system's savings back to whoever's paying for the capital, the person with the checkbook has no financial reason to write the check.

This is the split-incentive problem, and it's the reason multifamily solar adoption in California has lagged single-family adoption for years, not a technology or cost issue on its own (source: KPBS, Canary Media reporting on the policy landscape).

California built two structurally different fixes. Virtual net metering (and its successor, the net billing tariff) is a billing mechanism: it lets a property owner allocate one interconnected system's credits across multiple accounts on one property, common-area and tenant alike, in whatever split the owner sets. SOMAH is a program requirement layered on top: for projects that qualify, at least 51% of the energy produced must go to tenants as bill credits, not to the owner. VNEM/VNBT makes sharing possible. SOMAH makes it mandatory, for the subset of buildings that qualify. Which one applies to your property is the single most important fact to establish before running any other numbers.

How the money moves: VNEM and its replacement, VNBT

Virtual net energy metering (VNEM) was the original CPUC tariff that let a single solar installation's output be divided across a multifamily property's common-area and individual tenant meters. As of February 15, 2024, new applicants use its replacement, the Virtual Net Billing Tariff (VNBT), under CPUC Decision 23-11-068. The one carve-out: SOMAH and MASH projects keep the legacy VNEM tariff rather than moving to VNBT.

Under VNBT, exported power is compensated at the Avoided Cost Calculator (ACC) rate rather than retail rate — the same shift NEM 3.0 made for single-family export credits. Residential tenant ("benefiting") accounts get 15-minute interval netting against their allocated share, the closest thing to old-style netting that survives under the new tariff. Nonresidential common-area accounts instead get dollar-denominated bill credits with no netting, and can sit on any applicable rate schedule.

We are not quoting a specific VNBT export rate in cents per kWh for multifamily accounts here — as of this writing, PG&E and SDG&E had published 2026-vintage ACC data but SCE had not, and the figure is not directly comparable to the residential NEM 3.0 export range (roughly 5-8 cents/kWh) the brand cites elsewhere on single-family pages. One fixed mechanic worth knowing operationally: once an owner sets the percentage split across common-area and tenant accounts, that split has to hold for a minimum of 12 months before it can be revised.

SOMAH: the program built specifically for affordable housing

SOMAH (Solar on Multifamily Affordable Housing) exists to solve the split-incentive problem directly rather than just enabling a workaround. Eligibility requires all of the following: the property is deed-restricted low-income rental housing; it has a minimum of 5 units; every unit is individually metered; the property is existing construction (new construction only qualifies if the system exceeds what code already requires); and it's served by PG&E, SCE, SDG&E, Liberty, or PacifiCorp. On top of that baseline, at least one of four conditions must also be true: 66% or more of residents are at or below 80% of area median income, the property sits in a disadvantaged community (top 25% on CalEnviroScreen), the property is tribally owned, or it's owned by a public housing authority.

The program's core mechanism is the 51% rule, confirmed directly against calsomah.org's current eligibility page: at minimum, 51% of the total energy a SOMAH project produces must flow to tenants as bill credits rather than to the owner or common areas.

On incentive dollar amounts, calsomah.org's currently published rate table (checked September 2026) shows tenant-allocated capacity earning $3.50 per AC-watt if the project stacks no other tax credit, stepping down to $2.45 if it also uses the federal ITC and $1.75 if it stacks both the ITC and the Low-Income Housing Tax Credit. Common-area-allocated capacity follows the same pattern: $1.19, $0.87, and $0.65 per AC-watt across those same three tiers. A storage add-on, where available, runs a flat $1.10 per watt-hour regardless of tax-credit stacking. Because SOMAH's table steps down as statewide capacity is claimed, confirm the currently active step directly against calsomah.org's live incentive table before budgeting to these numbers.

One closed-program clarification worth having on hand: SOMAH's predecessor, MASH, stopped accepting new applications at the end of 2021, but existing MASH projects' legacy VNEM tariffs remain open for enrollment. If you're evaluating an older multifamily solar installation, it may already be on a MASH-era VNEM tariff that current applicants can no longer access.

SOMAH's pace: funded, open, and accelerating

SOMAH carries a $100 million/year funding authorization and a hard target of 300 MW installed statewide by 2032. Older reporting on this program understated where it stands today: calsomah.org's own tracker (checked September 2026) puts the program at more than 103 MW from completed and active projects combined — roughly a third of the 2032 target — with $38 million paid out in incentives in 2025 alone, 220 applications submitted that year, and more than 70 already filed in 2026, which the program administrator describes as on pace for a post-launch record. If you see a much lower installed-capacity figure cited elsewhere for SOMAH, check its date before repeating it — this program's numbers have moved fast enough recently that anything from early 2025 or before will materially understate where it stands now.

Two recent CPUC decisions are relevant if you're evaluating a project timeline. Decision D.24-11-006, issued November 14, 2024, directed a set of program updates — including expanding eligible installation costs, suspending the old buydown calculator, and adding an integrated-storage incentive — that were folded into the SOMAH Program Handbook via an advice letter that took effect June 6, 2025. Decision D.26-07-029, dated July 2026, sets the process for the program's eventual 2032 closure and reportedly updates multifamily property eligibility standards. The specific content of those eligibility changes hadn't been independently verified against the decision text at the time of this research, so if your project's eligibility is borderline, confirm directly against the current calsomah.org handbook rather than relying on older summaries — including this one.

Title 24: what's actually mandatory, and for whom

Title 24's multifamily solar mandate applies only to new construction. If you already own the building, none of this section requires you to do anything — SOMAH, VNBT, and ordinary commercial solar economics are what apply to existing buildings instead.

For low-rise multifamily (three habitable stories or fewer), a solar PV mandate has been in place since the 2019 Energy Code took effect January 1, 2020 — six years running, not a new requirement. System sizing is generally the smaller of what the roof's solar access allows or a formula-based size, with a floor around 0.8 watts-DC per square foot of conditioned floor area, subject to exceptions.

For high-rise multifamily (four stories or more) and hotels/motels, the mandate expanded with the 2022 Energy Code, effective January 1, 2023, to require both PV and battery storage. The PV system must be sized to cover 60% of the building's estimated electricity use, and a battery storage system is required unless a specific exception applies.

The current cycle — the 2025 Energy Code, adopted July 2025 and effective for projects permitted on or after January 1, 2026 — is in force as of this writing and continues both mandates; multiple industry summaries describe it as the most aggressive expansion of the solar-and-storage requirements to date. High-rise multifamily's battery requirement continues, with listed exceptions. One design detail carried forward into this cycle: a low-rise or single-family PV system's required size can be reduced by up to 25% if paired with at least 7.5 kWh of JA12-compliant battery storage per dwelling. These figures are consistent across several secondary code summaries, but none of them is the California Energy Commission's own code text — confirm against the CEC's published 2025 Energy Code before finalizing plans or a permit submission.

The federal tax credit deadline most multifamily owners don't know about

Multifamily solar — whether serving common areas, tenant meters, or both — is a commercial-use asset when owned by the property owner or a third party, so it accesses Section 48E (the Clean Electricity Investment Credit), not the residential 25D credit that ended December 31, 2025. This applies whether or not the property is SOMAH-eligible.

SOMAH-eligible affordable housing gets an additional lever: the 48E(h) Low-Income Communities Bonus Credit, available for facilities under 5 MW. It adds 10% for a project located in a low-income community or on tribal land, or 20% for a "qualified low-income residential building project" — which explicitly includes multifamily rental property where at least 50% of the financial value of the energy produced goes to low-income occupants. The 2026 application window for this bonus ran February 2 through August 7, 2026, and has already closed as of today; the timing for the next application cycle hadn't been announced as of this writing.

The deadline that matters most for anyone weighing a project right now: a solar facility under 48E that begins construction after July 4, 2026 must be placed in service by December 31, 2027 to get any credit at all — not a reduced credit, none (this is the statutory rule from the One Big Beautiful Bill Act, signed July 4, 2025, with IRS mechanics in Notice 2025-42). A project that began construction on or before July 4, 2026 isn't subject to that placed-in-service cliff at all — it only has to show continuous work toward completion, which the IRS treats as automatically satisfied if the project is placed in service within four years of the year construction began. A project that broke ground in 2025, for example, is covered through the end of 2029 without having to prove anything further; miss that four-year window and the project can still qualify, but only by showing continuous construction as a facts-and-circumstances matter, a harder standard to document.

One complication as of this writing: a federal court (D.D.C., in Oregon Environmental Council v. IRS, decided June 6, 2026) vacated Notice 2025-42 itself, ruling the IRS had acted arbitrarily in how it tightened the test for proving when construction began — specifically, its near-elimination of the older 5% safe-harbor test for solar projects over 1.5 MW. That ruling reopened the older, more permissive standard, under which a project can show it began construction either through physical work of a significant nature or by having paid or incurred 5% of total project cost. It did not disturb the two dates that matter most here — July 4, 2026 and December 31, 2027 both remain in force — but the government is expected to appeal, on a timeline that will likely run past July 4, 2026 itself. Treat which construction-start test currently applies as unsettled, and confirm it with a tax professional before treating any contractor's "we already started" representation as bankable.

As of September 5, 2026, the July 4 begin-construction cutoff has already passed. Any multifamily solar project not already under construction is racing the December 31, 2027 placed-in-service deadline with no way around it. Battery storage that isn't paired with solar or wind has a materially longer runway, with a start-of-construction deadline of 2033 — a real point of contrast if a project is deciding whether to prioritize PV now and storage later.

Batteries: near-mandatory in practice, unevenly subsidized right now

All three ratepayer-funded SGIP budgets — General Market, Equity, and Equity Resiliency — closed to new applications December 31, 2025. What's left is the RSSE AB 209 budget, a separate $280 million state-funded pot reserved for income-qualified households (at or below 80% of area median income, or enrolled in CARE, FERA, or ESA) installing paired solar-plus-storage or a storage-only retrofit on existing solar.

Its status isn't one number statewide, and it changes step-by-step as funds get claimed. As of early September 2026, selfgenca.com's live program tracker showed PG&E's plain AB 209 sub-budget actively accepting new reservations (a step that opened September 30, 2025), while several other utility territories were showing waitlist status on that same budget category at the same time — and a related but separate sub-budget split for customers of publicly owned utilities added another layer of variation on top of that. Don't take a single blanket "it's open" or "it's closed" answer from any source, including this one — pull the current step status for your specific utility territory directly from selfgenca.com/home/program_metrics before budgeting a rebate in.

For multifamily specifically, RSSE-type storage programs typically require 5 or more rental units and the same low-income or disadvantaged-community qualification tests SOMAH itself uses — so a property that doesn't clear SOMAH's eligibility bar generally won't clear this one either. Combine that with the fact that Title 24 only mandates battery storage for new high-rise construction, and the practical result is straightforward: most existing multifamily properties adding storage today are either paying full commercial battery pricing with no state rebate underneath it, or sitting on a waitlist with no guaranteed timeline. This mirrors what's already true on the residential side of this business — batteries are increasingly necessary given how export compensation works under VNBT, but the subsidy layer that used to soften that cost has mostly closed.

What a multifamily-scale system actually costs

No multifamily-specific installed cost-per-watt benchmark exists in published data as of this writing — that's a real gap, not an oversight, and it's worth stating rather than inventing a number. The best available substitute is general commercial solar pricing by system size, since most apartment complexes (roughly 150-300 units) land in the mid-market band once common-area and tenant-offset capacity are combined: small commercial systems (10-50 kW) run $1.83-$3.50 per watt-DC installed; mid-market systems (50-500 kW, the band most multifamily properties fall into) run $1.40-$2.00 per watt-DC; large commercial and industrial systems (500 kW and up) run $1.10-$1.70 per watt-DC. For a broader reference point, SEIA reported commercial solar averaging roughly $1.72 per watt-DC nationally in 2025.

Battery storage adds roughly 30-60% to total project cost on top of the PV system, with commercial lithium battery pricing running approximately $400-$700 per kWh installed in California. These figures carry the same caveat the rest of this site's commercial cost pages carry: California-specific pricing hasn't been independently verified across three separate public sources, so treat these as directional planning numbers, not a quote. Get an actual bid before committing capital.