What a 1 MW Commercial Solar System Costs in California in 2026

The Installed Cost for 1 MW

No primary source publishes a California installed price for a 1 MW commercial system. The closest primary figures are LBNL's reported prices for 2023 installations: large non-residential systems (over 100 kWdc) came in at $1.70 to $3.10 per watt, 20th to 80th percentile, nationally. NREL's last commercial rooftop model, a 200 kWdc system in Q1 2022, came in at a modeled market price of $1.84 per watt (2021 dollars).

For a straightforward 1 MW rooftop or ground-mount system in California, LBNL's band puts total installed cost at roughly $1.7 million to $3.1 million before any tax credit. Lower figures circulating on aggregator and SEO sites are not supported by primary sources and shouldn't be treated as a baseline for budgeting a real project. Get at least three EPC bids and compare them against the band.

Roof, Ground, or Carport: The Mounting Decision

Rooftop is usually the cheapest path structurally, assuming the roof itself is sound and large enough; the designer will tell you how much usable roof area 1 MW needs with your module choice and setbacks. The variable that doesn't show up in a $/W figure is roof condition — a roof that needs reinforcement or replacement before the array goes on adds cost outside the installed price, and that cost is specific to the building, not something to estimate generically.

Ground-mount avoids roof work but adds civil work, fencing and permitting, and a standalone 1 MW ground-mount carries more of those costs per watt than a utility-scale project; ask the designer for the acreage your layout needs. Utility-scale benchmarks don't transfer to a 1 MW site.

Carport is usually the most expensive option — engineered steel canopy structures, foundations, and wind and snow loading push the price well above rooftop. That premium only makes sense where the covered parking itself has independent value to the site (retail, office, campus). No primary source publishes a California carport price, so get it bid as its own line.

The 48E Tax Credit and the Line at Exactly 1 MW

Section 48E replaced the older investment tax credit structure and set a base rate of 6% of qualified project cost. Getting to the full 30% rate requires meeting prevailing wage and apprenticeship (PWA) requirements — and here is where 1 MW stops being just a size description and becomes the exact regulatory threshold. A facility with maximum net output under 1 MW AC is automatically exempt from PWA and gets 30% regardless of labor practices. A facility at or above 1 MW AC must satisfy PWA to get the higher rate, or the credit falls back to 6%.

The measurement is AC nameplate, not DC capacity — a project marketed as '1 MW' based on DC panel rating can land on either side of the line depending on inverter sizing and how the project is configured. This is worth resolving with your EPC and tax advisor before assuming which rate applies, and worth confirming against the statutory language directly (IRS guidance at irs.gov/PWAFAQS and the Form 3468 instructions) rather than taking any summary, including this one, at face value.

Beyond the base rate, bonus adders exist for domestic content, energy community location, and low-income siting. The IRS sets the domestic-content adder at 10 percentage points for a project under 1 MW, one that began construction before January 29, 2023, or one meeting prevailing-wage and apprenticeship rules, and 2 points otherwise; the project must be built with set percentages of US-made steel, iron and manufactured products. Confirm eligibility for any specific adder with tax counsel before including it in a project pro forma.

The Deadline That Already Passed

This is the fact that should reshape how this page is read: under the One Big Beautiful Bill Act, signed July 4, 2025, solar facilities under 48E face an early termination structure with two clocks. The first required beginning construction by July 4, 2026 to preserve credit eligibility on the original timeline. As of September 5, 2026, that date has already passed.

The second clock now governs: any project beginning construction after July 4, 2026 must be placed in service by December 31, 2027, or there is no investment tax credit at all — not the reduced 6% rate, none. For a 1 MW project, that's a real construction and commissioning timeline to hit, not a distant planning consideration.

'Beginning construction' was defined by IRS Notice 2025-42 as either physical work of a significant nature or, for smaller solar facilities, a 5% cost safe harbor. The notice limited the 5% safe harbor to 'low-output' solar facilities of 1.5 MW AC or less, which mattered directly for a project sized right at 1 MW. On June 6, 2026, the U.S. District Court for the District of Columbia vacated Notice 2025-42 in full as arbitrary and capricious and remanded it to the IRS, in Oregon Environmental Council v. IRS. Which construction-start rules apply after that ruling is a question for tax counsel; treat it as unsettled. None of this changes the underlying July 4, 2026 / December 31, 2027 statutory deadlines above, which come from the OBBBA itself and are unaffected by the notice's litigation status. Confirm the live status of both the notice and your construction-start method with tax counsel before filing anything on the strength of either test.

Depreciation: 100% Bonus, and Check the Class Life

Section 168(k)(1)(A) now provides a 100% first-year allowance for qualified property acquired after January 19, 2025, and the statute as amended in 2025 sets no phase-down. That's a meaningful benefit on its own: the full depreciable basis can be expensed in year one, separate from the ITC.

If you elect out of the allowance or cannot use all of it in year one, 26 U.S.C. §168(e)(3)(B)(viii) classifies §48E qualified property and energy storage technology as 5-year property. It matters more as a contingency if bonus depreciation is reduced in a future tax year, or for a project owner without enough taxable income to use the full deduction in year one.

Interconnection: Rule 21 Won't Fast-Track You

Rule 21 governs distribution-level interconnection at PG&E, SCE, and SDG&E (it doesn't apply to publicly owned utilities like LADWP, SMUD, or Roseville, which set their own terms entirely). Fast Track — the quickest review path — applies to systems of 500 kW or less at secondary voltage. A 1 MW system exceeds that threshold and should expect Supplemental Review, the Independent Study Process, or a full Detailed Study, any of which extends the review timeline well beyond what a 500 kW project would see.

The bigger risk isn't time, it's cost. California applies a cost-causer-pays model: if the utility determines distribution network upgrades are needed to accommodate your interconnection, you generally pay for them, even when those upgrades benefit other customers who interconnect after you. The CPUC has directed utilities to let projects use existing Integration Capacity Analysis hosting capacity where possible to avoid triggering upgrade costs, but this isn't guaranteed for every site. Budget for the possibility of a five- or six-figure network upgrade cost that doesn't show up in your installed $/W quote, and note that CPUC opened a new interconnection rulemaking (R.25-08-004, via an Order Instituting Rulemaking adopted August 14, 2025) that remains active — Rule 21 mechanics could still change before your project reaches the interconnection queue.

Financing a 1 MW Project

Three structures cover most 1 MW commercial deals. Direct ownership lets you use the 48E credit and bonus depreciation yourself, assuming you have the tax appetite to absorb them. A PPA structure routes the tax benefits through a third-party owner or tax-equity investor, and the per-kWh price in the contract may or may not reflect part of that value — the same structural logic that makes PPAs relevant on the residential side, now operating through 48E.

A 1 MW project is small for traditional partnership-flip tax equity, which is usually arranged for much larger portfolios, and it may also be small for a standalone sale-leaseback. It may need to be bundled with other assets, sized up, or financed through a smaller regional lender. Get direct quotes before assuming any of these structures is available at this exact size.

On PPA pricing specifically: this page does not repeat the published ranges for California commercial deals, which vary too widely to rely on. Get live quotes tied to your specific offtake structure and utility territory, and compare the contracted rate and escalator with your tariff over the full term.

Batteries and SGIP: Check Before You Assume

As of September 22, 2026, the California Self-Generation Incentive Program's Large-Scale Storage category is at Step 5 and closed for all four program administrators — CSE, SCE, SoCalGas, and PG&E — per selfgenca.com's program metrics page.

The listed Step 5 rate is $0.25 per watt-hour standard, or $0.18/Wh when stacked with the federal ITC. Right now, don't plan a 1 MW project's economics around SGIP being available — check selfgenca.com/home/program_metrics directly before assuming any dollar figure applies.