Industrial Solar in California: Rates, Sizing and Rules for Plants and Manufacturers

Industrial solar in California means on-site systems at plants, factories and processing sites, and they run larger than other business systems. The 51 industrial-sector systems PG&E, SCE and SDG&E connected in 2025 had a median size of 195 kW DC, and 21 were ground-mounted. The economics turn on demand charges, operating hours and space more than on panel price.

This page covers what is different about industrial sites. For the steps every commercial project shares, see how to compare commercial solar companies and EPCs, and for every business guide, the commercial solar hub. Sources were checked September 23, 2026.

What industrial solar looks like in California

In CRR's count of the CPUC's DGStats interconnection data, 51 PV systems in the industrial customer sector were connected by the three investor-owned utilities in 2025: 33 by PG&E, 17 by SCE and one by SDG&E. Their median was 195 kW DC, the middle half ran from about 40 kW to 634 kW, and the group totaled about 53 MW DC. For comparison, the median across all 3,607 non-residential systems connected that year was 61 kW.

Mounting was split: 27 were on roofs, 21 on the ground and three mixed. Only eight were third-party owned, and five included battery storage. The sector label comes from the utility application, so some plants may be filed as commercial instead.

The national picture is similar. Berkeley Lab's 2026 data update names industrial buildings among the largest commercial business types for solar in 2025 and reports median industrial system sizes above 100 kW, with schools the only other segment that large.

The bill: demand charges decide the economics

Large industrial accounts pay heavily for demand, the highest rate of use in a short interval, not only for energy. On PG&E, Schedule B-19 applies to a customer whose maximum demand exceeded 499 kW for three consecutive months in the past year, and Schedule B-20 to one that exceeded 999 kW. Both bill three demand charges at once: a maximum demand charge set by the highest 15-minute interval at any time, a peak demand charge for 4 to 9 p.m., and a part-peak demand charge.

Solar produces most around midday, so it does little for the 4-to-9 p.m. peak charge, and one cloudy interval during a busy shift can still set the maximum demand charge for the month. SCE's business rate pages describe the same split between facilities-related demand charges, set by the month's highest demand at any time, and time-related demand charges, set during on-peak and mid-peak weekday hours. Ask for a bill model that shows the energy savings and the demand savings separately, and a second case with a commercial battery controlled to shave those intervals.

PG&E also offers Option R on B-19 and B-20 to customers with on-site renewable generation of at least 15% of their annual peak demand, subject to a 600 MW participation cap across its schedules. Ask any bidder whether the model assumes Option R and whether space remains under the cap.

Size to what the plant uses while the sun is up

New systems at PG&E, SCE and SDG&E take service under the Net Billing Tariff, which the CPUC says has applied to customers applying for interconnection since April 15, 2023. Exports earn credits based on the CPUC's Avoided Cost Calculator, usually below the retail rate, and the CPUC lists the size limit as the customer's annual load plus up to 50% if the customer attests to the need. In the 2025 industrial data, 16 systems were on the Net Billing Tariff and most of the rest on the older NEM 2.0 tariff, which new applications can no longer join.

The practical result: value comes from output the plant uses on site. A one-shift weekday operation exports much of its weekend production; a round-the-clock process load absorbs almost all of it. Give bidders 12 months of 15-minute interval data, your shift pattern and planned shutdowns, and ask for the share of production used on site.

The Energy Code and new industrial buildings

The Energy Commission's 2025 nonresidential solar guidance lists the new building types that must include solar under Section 140.10: among them office, retail, school and warehouse buildings, but not manufacturing buildings. Additions, alterations and unconditioned buildings are excluded, and the rules apply to permit applications submitted on or after January 1, 2026. A new distribution warehouse on a plant campus can be covered even when the plant is not. The Title 24 requirements guide goes through the calculation and exceptions.

Roofs, ground mounts and canopies at a plant

Industrial roofs carry exhaust stacks, vents, skylights and equipment that break up the usable area, and many are older metal or membrane roofs. Get a structural review and the roof's remaining life before comparing bids; the commercial solar roofing guide covers load checks, attachments and fire pathways.

Ground mounts on spare land avoid the roof but add fencing, trenching and a longer run to the switchgear, and 21 of the 51 industrial systems in 2025 went that way. Canopies over employee or truck parking are the third option, priced as a structure plus solar; see the commercial carport cost guide. Wherever the array goes, write down which production areas, loading lanes and emergency routes must stay clear during construction.

Cost, tax and ownership

No public source reports an industrial-only installed price. Berkeley Lab's Tracking the Sun 2024 summary found a 2023 median of $2.3 per watt for large (100 kW and up) California commercial systems before incentives. The commercial cost-per-watt guide breaks prices down by size, and the commercial panel wattage data shows the larger modules these projects use.

Size also matters for the federal credit. Under 26 U.S.C. §48E, a facility under 1 MW AC gets the 30% rate without the labor rules; a larger one needs the prevailing-wage and apprenticeship requirements to reach it. A solar facility whose construction began after July 4, 2026 gets no credit for property placed in service after December 31, 2027. The commercial solar tax credit guide covers the rest, and commercial financing options compares owning with a PPA or lease.

What to put in an industrial bid request

1. Twelve months of 15-minute interval data for every meter the project could serve, and the rate schedule on each.
2. Shift schedule, weekend and holiday operation, and planned shutdowns or expansions.
3. Roof drawings, age and warranty, or the land area and any easements for a ground mount.
4. Main switchgear rating and any planned electrical upgrades.
5. Which loads need backup power, stated separately from bill savings.
6. Site rules for contractors: safety training, access hours and production areas that stay closed.

Ask each bidder to return a line-item price, the DC and AC sizes, a monthly bill model on your actual tariff with and without a battery, and the licensed entity that will sign. If a developer offers to own the system, read what a solar developer does first.

When solar is the wrong move for a plant

Solar is a weak fit when most of the load runs at night, when the roof needs replacing within a few years and no land is available, or when you lease the building on a term shorter than the payback you are modeling. It also misleads if the proposal counts on demand-charge savings without interval data to back them. In those cases, fix the roof, the lease or the data first.

Frequently asked questions

California Rate Relief is a referral service. We are not a licensed contractor. The rates on this page are published tariff figures, not a bill estimate, and nothing here is tax advice.

Sources

Checked September 23, 2026.

• California Public Utilities Commission, DGStats Interconnected Applications Data Set (data through May 31, 2026). Counts are CRR's tabulation of 2025 PV systems.
• PG&E, Electric Schedule B-19 and Electric Schedule B-20 (rates effective March 1, 2026)
• SCE, business time-of-use rate plans
• CPUC, Net Energy Metering and Net Billing
• California Energy Commission, 2025 Nonresidential Solar PV
• LBNL, U.S. Distributed Solar and Storage: 2026 Data Update (August 2026) and Tracking the Sun 2024 executive summary (August 2024)
• 26 U.S.C. §48E, Office of the Law Revision Counsel (text in effect September 23, 2026)