Your Warehouse Pays All Month for Its Worst 15 Minutes
On most California business rates, one 15-minute spike sets your demand charge for the whole month. Solar covers the energy you use in daylight. A battery goes after the 4 to 9 PM peak that solar can't reach.
Can solar and storage lower a California warehouse electric bill?
Yes, for many owner-occupied warehouses using 50 kW or more. Solar offsets the energy you buy during daylight hours. A battery lowers the 4 to 9 PM demand charge that solar alone can't reach. Under the One Big Beautiful Bill Act, new solar projects must be running by December 31, 2027 to qualify for the federal credit.
Solar With Watts and the Mars commercial team design and install systems 50 kW and up for warehouses, distribution centers and industrial buildings near you, anywhere in PG&E, SCE, SDG&E or SMUD territory. Share 12 months of bills, and a Mars commercial specialist follows up.
What do warehouse owners ask first about solar?
Short, straight answers to the three questions owners and operations managers ask before anything else.
Is solar worth it for a warehouse in California?
Yes, for many owner-occupied warehouses using 50 kW or more. Big flat roofs, daytime operations and California's high business electric rates make a strong case.
Can solar lower my warehouse demand charges?
Partly. Solar trims daytime peaks, but most demand charges also bill the 4 to 9 PM window. A battery covers that evening peak after the sun goes down.
Who installs commercial solar for warehouses near me in California?
Solar With Watts and the Mars commercial team, licensed under CSLB number 1065773. We design and install systems 50 kW and up across PG&E, SCE, SDG&E and SMUD territory.
Why is a warehouse electric bill so different from a home bill?
Your business bill charges you two ways at once. Energy charges bill every kilowatt-hour you use. Demand charges bill your single highest 15-minute stretch of the month, in kilowatts.
That is why one hot afternoon matters so much. If chargers, compressors and HVAC all run hard for the same 15 minutes, that spike can set the demand charge for the entire month.
Energy you use (kWh)
Billed for every hour you run. Rates are highest from 4 to 9 PM.
Solar's jobYour biggest spike, any hour (kW)
Set by the highest 15 minutes of the month, day or night. Solar helps only when the spike happens in strong sun.
Solar + batteryYour spike from 4 to 9 PM (kW)
Most utilities add a second demand charge for the evening peak. Solar output is fading or gone by then.
Battery's jobHow do PG&E, SCE, SDG&E and SMUD bill warehouse demand?
| Utility | Typical warehouse rate | Demand charges | Peak window |
|---|---|---|---|
| PG&E | B-10 under 500 kW; B-19 from 500 to 999 kW; B-20 at 1,000 kW and up | On B-19: $37.37 per kW at any hour, plus $46.16 per kW for the summer 4 to 9 PM peak | 4 to 9 PM, every day |
| SCE | TOU-GS-3 from 200 to 500 kW; TOU-8 over 500 kW | Two charges: facilities-related demand on your monthly peak at any hour, plus time-related demand on your peak during weekday peak hours | 4 to 9 PM, weekdays |
| SDG&E | AL-TOU-M from 20 to 199 kW; AL-TOU at 200 kW and up | On AL-TOU-M: $21.10 per kW on your monthly peak, plus an on-peak demand charge | 4 to 9 PM, every day |
| SMUD | CI-TOD1 through CI-TOD4, assigned by your peak kW | A site infrastructure charge on your highest kW in the past 12 months, plus a summer peak demand charge of about $10 to $12 per kW | 4 to 9 PM, weekdays |
Bundled rates at secondary voltage: PG&E effective March 1, 2026; SDG&E effective June 1, 2026; SMUD effective January 1, 2026. Utilities change these rates several times a year, so check your own bill or the current schedule. SMUD's demand charges run lower, so savings there lean more on how much energy you use.
Your bill shows which rate you are on and where your peaks land. Send 12 months of bills, and a Mars commercial specialist follows up.
Request a Commercial Review →Which commercial solar options fit a warehouse or industrial site?
Most warehouses use more than one. Mars offers rooftop solar, solar carports, ground mounts and battery storage. A Mars commercial specialist looks at your roof, parking, land and bills to find the right mix.
| Option | Best for | Watch out for |
|---|---|---|
| Attached rooftop | Metal roofs, and roofs with little spare weight capacity. Racking bolts to the structure instead of relying on heavy ballast. | Every attachment goes through the roof, so flashing and your roof warranty need to be planned up front. |
| Ballasted rooftop | Flat membrane roofs with room to spare structurally. Weighted racking sits on the roof with few or no penetrations. | Concrete ballast adds weight, so the roof structure needs an engineer's check first. Older roofs may not have the margin. |
| Solar carport | Employee and visitor parking. Adds shade, and the California Fire Code exempts carports from rooftop access pathways. | Needs foundations and steel, and more clearance over truck and trailer areas. Plan around lighting and drive aisles. |
| Ground mount | Unused land on the property, especially when the roof is old, crowded or too weak to carry panels. | The fire code requires a 10-foot brush-free area around the array. Trenching distance back to your service adds work. |
| Battery storage | Cutting the 4 to 9 PM demand charge, and evening or second-shift loads that solar can't reach. | Sizing should come from your 15-minute interval data, not just your monthly total. Placement goes through fire code review. |
Each site is designed and engineered by the Mars commercial team. Systems start at 50 kW.
What does a common warehouse setup look like?
Rooftop solar covers daytime energy for lights, conveyors and HVAC. A battery handles the evening peak. If the roof falls short, a carport over the parking lot can add capacity without touching the building.
Which warehouse loads can solar and storage actually cover?
It depends on when your building works. A day-shift distribution center lines up with the sun. A two-shift plant or a cold storage building runs into the evening peak, so storage does more of the work.
Day-shift distribution
Busiest from morning to mid-afternoon
- What drives the bill: lighting, conveyors, dock equipment and HVAC on hot afternoons.
- Solar: runs during the same hours, so it can cover a large share of daytime energy.
- Battery: optional. Useful if afternoon cooling or late trucks push load past 4 PM.
Two-shift manufacturing
Running hard into the evening
- What drives the bill: motors, compressors and process equipment still running from 4 to 9 PM.
- Solar: covers the first shift's energy.
- Battery: carries the second shift through the evening peak, where demand charges run highest.
Cold storage and refrigerated
Running around the clock
- What drives the bill: refrigeration compressors that never stop, plus heavy cooling on summer afternoons.
- Solar: offsets the steady daytime load, and output peaks in the same hot months.
- Battery: trims the evening peak while compressors keep running.
Electric forklifts and truck charging
Spikes at shift change
- What drives the bill: many chargers starting at once, which can set a new monthly peak in 15 minutes.
- Solar: pairs well with midday charging windows.
- Battery: smooths charger spikes so they don't set your demand charge. SCE also offers separate EV rates for separately metered charging.
Planning a new or expanded logistics building?
California's AB 98 sets new design rules for new and expanded logistics projects starting in 2026. For larger sites and those in the state's warehouse concentration region, it phases in zero-emission forklift requirements between 2028 and 2030. More electric forklifts means more charging load, so plan your power early.
Will your warehouse roof carry solar panels?
Often, yes, but four things decide it: the roof's age, its spare structural capacity, the fire code clearances, and what's already up there. The Mars team reviews your roof and structure before a design is final, and handles the engineering, roofing and installation from there.
How old is the roof?
Panels are built to last for decades. If your roof membrane is near the end of its life, it usually makes sense to replace it before the array goes on.
Mars handles commercial roofing as well as solar, so the reroof and the array can be planned as one project.
Can the structure take the weight?
Commercial arrays typically add 3 to 6 pounds per square foot of weight. Ballasted systems add more, and wind uplift at roof corners has to be designed for too.
Older roofs often have less spare capacity than newer ones designed with solar in mind, so an engineer checks the numbers.
How much space does fire code take?
California requires clear walkways around the roof edge and between array sections so firefighters can work. On a big warehouse, those pathways take a real share of the roof.
The table below shows the main rules.
What's already up there?
Skylights, smoke and heat vents, HVAC units and roof hatches all need clearance. Each one cuts into the area that can hold panels.
A clean, open roof fits far more than one crowded with equipment.
What does the California Fire Code require on a commercial roof?
| Rule | What it requires |
|---|---|
| Roof edge clearance | A clear perimeter at least 6 feet wide around the roof edge. If either side of the building is 250 feet or less, it can drop to 4 feet. |
| Interior pathways | Pathways between array sections, spaced no more than 150 feet apart across the length and width of the roof. |
| Hatches and standpipes | A 4-foot pathway around roof access hatches, and a straight 4-foot pathway to roof standpipes and ventilation hatches. |
| Smoke and heat vents | A 4-foot pathway beside smoke and heat vents. Between array sections, either an 8-foot pathway or a 4-foot pathway with venting cutouts. |
| Carports | Parking shade structures and carports are exempt from these rooftop access rules. |
Source: 2025 California Fire Code, Section 1205, effective January 1, 2026. Your local fire official can adjust some requirements.
What helps speed up a roof review?
- The roof's age and material, plus any roof warranty
- Original building or structural drawings, if you have them
- Recent roof repairs, coatings or leaks
- 12 months of electric bills
Roof falls short?
A solar carport over employee parking or a ground mount on open land can carry the system instead. Neither puts weight on your building, and carports skip the rooftop fire code pathways.
Request a Commercial Review →What deadlines and incentives apply to warehouse solar in California?
One federal deadline drives the timing for most projects. A few state rules and one PG&E storage rate matter too, depending on your building and utility.
Under the One Big Beautiful Bill Act, solar projects that begin construction after July 4, 2026 must be placed in service by December 31, 2027 to qualify for the federal clean electricity credit.
Commercial projects need time for design, engineering, permits and utility interconnection. Starting the review early leaves room for all of it. Your CPA can confirm how the credit applies to your business.
Which rules and programs could affect your warehouse project?
| Program or rule | Who it applies to | What to know | Status |
|---|---|---|---|
| Federal clean electricity credit | Owners of new solar on business property | Solar starting construction after July 4, 2026 must be placed in service by December 31, 2027. Projects that began construction earlier follow different rules. | Available, with a deadline |
| PG&E Option S storage rate | PG&E B-19 and B-20 customers with a battery sized to at least 10% of their peak | Lowers monthly demand charges in exchange for daily peak charges and higher energy prices. Enrollment is capped, and PG&E posts the remaining space. | Open, capped |
| Title 24 solar and battery rules | Newly built nonresidential buildings | The 2025 Energy Code requires solar on new nonresidential buildings, and a battery too unless an exception applies. | Required for new builds |
| AB 98 warehouse standards | New logistics projects, and expansions that add 20% or more square footage | Sets design and operating standards starting January 1, 2026, including zero-emission forklift rules for some sites. | Required where it applies |
| Solar property tax exclusion | New solar systems in California | The state exclusion sunsets on January 1, 2027, so it covers only systems finished before then. Most new projects won't qualify. | Ending |
General information only, not tax or legal advice. Rules and program capacity change, so confirm the details with your CPA and your utility before you rely on them.
How can a warehouse pay for commercial solar and storage?
Mars sets up payment case by case, based on your site, your finances and how long you plan to hold the building. There are three main paths.
Cash
You own the system
You pay for the system and own it from day one. Every dollar of savings stays with your business.
- Credit: goes to you as the owner
- Best for: owners with capital who plan to hold the building
Bank financing
You own the system
A commercial lender spreads the cost over time. Your business still owns the system, and terms depend on the lender and your credit.
- Credit: goes to you as the owner
- Best for: owners who want ownership without a large upfront outlay
Select PPAs
A third party owns the system
With a power purchase agreement, another company owns the system and you buy the power it makes. PPAs are offered on select projects.
- Credit: stays with the PPA owner and isn't passed through in the pricing
- Best for: sites that want solar without owning the equipment
A proposal decision-makers can use
Mars provides a proposal your owners, partners or board can review before anyone signs.
Large systems and US-made equipment
For systems 1 MW and up, Mars designs to meet the US-made equipment rules.
Leasing your building?
The property owner usually needs to approve anything installed on the roof or lot. Bring them in early.
Not tax or financial advice. Talk with your CPA about which ownership path fits your business.
How do you get a commercial solar review for your warehouse?
Fill out the short form with your building details. There's no cost, and you don't need your bills to start.
What happens next
- You send your building detailsBuilding type, ownership, bill size, available space and timing, through the form.
- A Mars commercial specialist follows upThey check your site against the 50 kW minimum and ask for 12 months of bills if it looks like a fit.
- The Mars commercial team designs itThey review your roof, structure, parking, loads and ways to pay, then lay out your options.
- You get a proposal decision-makers can useA proposal your owners, partners or board can review before anyone signs.
Who owns the building, your electric utility, the roof's age, 12 months of bills, and 15-minute interval data if you can download it from your utility account.
What do warehouse owners ask about commercial solar?
Is solar worth it for a warehouse in California?
Yes, for many owner-occupied warehouses using 50 kW or more. Large flat roofs and daytime operations line up with solar production. California's business electric rates are among the highest in the country, so every kilowatt-hour you make yourself is worth more.
Can solar lower my warehouse demand charges?
Partly. Solar trims demand peaks that happen in strong sun. Most utilities also bill your highest demand from 4 to 9 PM, when solar output fades. A battery is what targets that evening peak.
Do I need a battery with warehouse solar?
Not always. A day-shift building that winds down by mid-afternoon may do well with solar alone. Two-shift plants, cold storage and sites with heavy evening charging usually need storage to cut the 4 to 9 PM demand charge.
How do I know if my warehouse roof can hold solar panels?
An engineer checks it. Commercial arrays typically add 3 to 6 pounds per square foot, and ballasted systems add more. The Mars team reviews your roof and structure before a design is final.
Should I replace my warehouse roof before going solar?
Often, yes, if it is near the end of its life. Panels are built to last for decades. Mars handles commercial roofing as well as solar, so the reroof and the array can be one project.
How much roof space does California fire code take?
At least 6 feet around the roof edge, or 4 feet if either side of the building is 250 feet or less. Clear pathways are also required between array sections and around hatches and vents.
Can I put solar on a warehouse I lease?
Sometimes. The property owner usually needs to approve anything installed on the roof or lot. If you lease, bring your landlord into the conversation early.
What is the deadline for the federal solar credit on a warehouse?
December 31, 2027. Under the One Big Beautiful Bill Act, solar projects that begin construction after July 4, 2026 must be placed in service by then. Commercial projects take time, so start early and confirm the details with your CPA.
Can solar go over our parking lot or truck yard?
Yes. Solar carports can cover employee and visitor parking, and areas with trucks and trailers need extra height and clearance planning. California's fire code exempts carports from the rooftop access pathways.
What do I need to send for a commercial solar review?
Start with the short form on this page. If your site looks like a fit, a Mars commercial specialist follows up and asks for 12 months of electric bills. Interval data from your utility account helps size a battery.
Not quite the right fit?
This page is for warehouse and industrial sites using 50 kW or more in PG&E, SCE, SDG&E or SMUD territory. If that's not you, one of these is a better place to start.
Smaller building or a home?
Systems under 50 kW aren't a fit for the commercial team.
Try the Solar Panel Estimator →Leasing without owner sign-off?
Projects need the property owner on board. Share this page with your landlord, then come back together.
Request a review together →Not a warehouse?
We cover other commercial properties too.
Different utility?
Outside PG&E, SCE, SDG&E or SMUD territory, check where we work first.
See service areas →What Are Your Worst 15 Minutes Costing You?
Send your building details and a Mars commercial specialist follows up. Solar must be running by December 31, 2027 to qualify for the federal credit, so the best time to start the review is now.