Your Store Is Busiest When Power Costs the Most
On most California business rates, the most expensive power runs from 4 to 9 PM, the same hours shoppers fill your store. Solar covers the energy you use in daylight. A battery goes after the evening peak, and carports turn customer parking into shade.
Can solar and storage lower a California retail or office electric bill?
Yes, for many retail centers and office buildings using 50 kW or more. Solar offsets the energy you buy in daylight, which fits office hours well. A battery lowers the 4 to 9 PM peak charges that evening store hours run into. 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 shopping centers, stores, medical offices and office buildings near you, anywhere in PG&E, SCE, SDG&E or SMUD territory. Whether you occupy the building or lease it to tenants, share 12 months of bills and a Mars commercial specialist follows up.
What do retail and office property owners ask first about solar?
Short, straight answers to the three questions owners, landlords and property managers ask before anything else.
Is solar worth it for a shopping center or office building in California?
Yes, for many retail and office properties using 50 kW or more. Solar offsets daytime energy, and a battery can cut the 4 to 9 PM peak charges.
Can solar work if every tenant in my building has their own meter?
Often, yes. California utilities offer billing plans that share one system's credits across tenant meters at the same service point. A Mars commercial specialist looks at your meter setup.
Who installs commercial solar for retail and office buildings in California?
Mars Home Solutions, CSLB number 1065773, designs and installs it with Solar With Watts. Mars handles commercial roofing, carports, battery storage and all engineering and construction.
Why is a retail or office 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. When rooftop HVAC units, lights and coolers all run hard for the same 15 minutes, that spike can set the demand charge for the entire month.
Offices: busiest from about 8 to 5
Most office energy is used while the sun is up. That lines up well with solar, which covers a large share of the workday load directly.
Stores: open right through 4 to 9 PM
Shoppers, lights, refrigeration and AC keep running into the evening peak, when power costs the most and solar has faded. That is where a battery earns its place.
Energy you use (kWh)
Billed for every hour you are open. 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. On hot days that is often HVAC starting up while coolers and lights are already running.
Solar + batteryYour spike from 4 to 9 PM (kW)
Most utilities add a second demand charge for the evening peak. Evening store hours land squarely inside it.
Battery's jobHow do PG&E, SCE, SDG&E and SMUD bill retail and office demand?
| Utility | Typical retail or office rate | Demand charges | Peak window |
|---|---|---|---|
| PG&E | B-10 from 75 to 499 kW; B-19 for larger centers and office buildings | On B-19: $37.37 per kW at any hour, plus $46.16 per kW for the summer 4 to 9 PM peak. B-10 has a lower demand charge and higher energy rates. | 4 to 9 PM, every day |
| SCE | TOU-GS-2 from 20 to 200 kW; 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 from 21 to 299 kW; CI-TOD2 from 300 to 499 kW | A site infrastructure charge on your highest kW in the past 12 months, plus a summer peak demand charge | 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. In a multi-tenant building, each tenant meter usually carries its own rate and its own demand charge.
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 →What are the solar options for a retail center or office building?
Most retail and office sites have two places to put solar: the roof and the parking lot. A battery handles the hours the panels can't. Here is where each one fits and what to watch for.
| Option | Best for | Watch out for |
|---|---|---|
| RooftopAttached or ballasted | Single-story stores, strip centers and office buildings with open flat roofs. Uses space you already own and stays out of sight from the street. | Rooftop HVAC units, skylights and California fire code access pathways all take usable space. A roof near the end of its life is often replaced first. Mars handles the commercial roofing. |
| CarportOver customer and staff parking | Centers and offices with large surface lots. Shades customers and staff, and every visitor sees it. Fire code exempts carports from the rooftop access pathways. | Covering existing parking triggers CALGreen EV charging requirements, scaled to the spaces covered. Needs steel and foundations, plus clearance for delivery trucks, drive aisles and lot lighting. |
| Ground mountOn open land beside the building | Office parks and suburban campuses with unused land next to the building. Easy to angle toward the sun and maintain. | Rare at retail sites, where land usually goes to parking or pads. Zoning, setbacks and fencing apply, and the land is tied up for decades. |
| Battery storagePaired with any of the above | Stores open into the evening, grocery and food sites with refrigeration, and buildings with sharp demand spikes. Targets the 4 to 9 PM peak. | Sizing depends on 15-minute interval data from your utility account. New buildings permitted under the 2025 Energy Code often need a battery with their solar. |
Every design is engineered by the Mars commercial team. EV charging counts under CALGreen depend on the number of spaces covered and the code edition your permit falls under.
Roof plus parking lot is the common mix
Many retail centers fill the roof first, then add carports over the rows closest to the entrance. Offices with small roofs and big lots often lead with carports. A Mars commercial specialist looks at both before recommending a layout.
Which retail and office loads can solar and storage actually cover?
It depends on what runs in your building and when. According to the U.S. Energy Information Administration's Commercial Buildings Energy Consumption Survey, lighting and refrigeration make up about half the electricity a typical retail store uses.
Office buildings look different. In the same survey, ventilation, computers, lighting and cooling lead their electricity use, and most of it happens during daylight hours.
Single-tenant store
Open about 9 AM to 9 PM
Big box, pharmacy, auto parts or furniture stores that own or lease the whole building.
- Main loads: lighting, rooftop AC, display cases
- Problem hours: late afternoon into the 4 to 9 PM peak
Grocery-anchored center
Coolers run 24/7
Refrigeration sets a load that never shuts off, so the building uses power all night and through the evening peak.
- Main loads: refrigeration, freezers, lighting, AC
- Problem hours: hot afternoons and every evening
Strip center
Mixed hours, many meters
Restaurants, salons, services and shops, each on its own meter, plus the owner's meter for lot lights and common areas.
- Main loads: tenant kitchens and AC, parking lot lighting
- Problem hours: dinner hours for food tenants
Office building
Busiest 8 to 5, weekdays
Single-tenant headquarters or multi-tenant office buildings and business parks.
- Main loads: ventilation, computers, lighting, cooling
- Problem hours: hot afternoons when HVAC peaks
Medical office or clinic
Long days, steady equipment
Dental, urgent care, imaging and specialty clinics, often with extended hours.
- Main loads: HVAC, imaging, sterilizers, medical refrigeration
- Problem hours: equipment spikes and evening appointments
Adding EV chargers to your lot?
Chargers can add a large new load, and evening charging can set your demand peak. A carport over existing parking also triggers EV charging requirements, so plan solar, storage and chargers together. PG&E's Business EV rate can put chargers on their own meter, and the Mars commercial specialist reviews how chargers fit your design.
Who saves when every tenant has their own meter?
In most shopping centers and multi-tenant office buildings, tenants pay their own electric bills. One solar system on the roof or over the lot connects at the building's service point, so the real question is how its value reaches each meter.
California utilities offer billing plans built for exactly this. Which one fits depends on whose name is on each meter.
Setup 1
One owner pays one bill
The building is on a single meter or a master meter, and the owner pays the utility. Solar lowers that bill directly.
If tenants reimburse power through common area charges or a set rate in the lease, the savings flow through the way the lease says.
Setup 2
Tenants on their own meters
A virtual billing plan lets one system share its credits across tenant meters and the common area meter at the same service point. SDG&E calls it the Virtual Solar Billing Plan, PG&E covers it under Schedule NEMV and its net billing successor, and SCE offers its own version.
The owner sets each meter's share, and shares can change as tenants come and go.
Setup 3
One owner, several meters
If the same customer holds several meters on the same or adjacent parcels, an aggregation plan can apply one system's credits across all of them. SDG&E calls it Solar Billing Plan Aggregation.
This fits owner-occupied campuses and buildings with separate house, lighting and HVAC meters.
These plans follow California's newer net billing rules, so exported power earns less than power you use on site. That is why systems are sized to what the building uses, often with a battery. SMUD runs its own programs, so the options differ there.
What does the lease decide?
- Who controls the roof and lot. Under most triple-net (NNN) leases, the tenant pays utilities, taxes, insurance and upkeep. The owner usually still controls the roof structure and parking lot, so any project needs owner sign-off.
- Who pays and who saves. If the owner pays for the system but tenants pay the bills, the lease or an amendment spells out how savings are shared.
- Selling power to tenants. California regulates who can sell electricity. Most owners share savings through a utility billing plan or the lease, not by billing tenants for power directly.
- Lease terms versus system life. Panels last for decades and leases turn over. Virtual billing shares can move to the next tenant.
- Roof work. Check the lease for roof penetrations, roof warranties and who pays if panels come off for a reroof.
What to have ready
- A list of every meter and account at the property
- 12 months of bills for each meter you control
- A tenant list with lease end dates
- Roof age and any roof warranty
- A site map showing parking rows
Owner, landlord or tenant? A Mars commercial specialist looks at your meters, leases and tenant mix before recommending a setup. Tenants, bring your landlord into the conversation early.
Request a Commercial Review →This section is general information, not legal or tax advice. Review lease changes and power-sharing arrangements with your attorney and CPA.
What deadlines and incentives apply to retail and office solar in California?
One federal deadline drives the timing for most projects. A few state building rules matter too, especially if you are building new or adding carports over your parking lot.
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. Multi-tenant sites can also need lease and owner sign-offs. 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 retail or office 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 |
| Title 24 solar and battery rules | Newly built office, retail and grocery buildings, including unleased tenant space | The 2025 Energy Code requires solar on these buildings for permits filed on or after January 1, 2026, and a battery too unless an exception applies. | Required for new builds |
| CALGreen EV charging for carports | Owners adding solar carports over existing parking | New solar over existing spaces triggers EV-capable spaces and chargers, scaled to the spaces covered. The 2025 code sets separate counts for office and retail parking. | Required where it applies |
| PG&E Option S storage rate | Larger PG&E sites on B-19 or B-20 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 |
| Solar property tax exclusion | New solar systems in California | The state exclusion stops applying on January 1, 2027, so it covers only systems finished before then. No extension has passed, and 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 retail center or office building pay for commercial solar and storage?
Mars sets up payment case by case, based on your site, your finances, your tenants and how long you plan to hold the property. There are three main paths.
Cash
You own the system
You pay for the system and own it from day one. The savings stay with whoever pays the electric bills, as your leases set out.
- Credit: goes to you as the owner
- Best for: owners with capital who plan to hold the property
Bank financing
You own the system
A commercial lender spreads the cost over time. You still own 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.
Tenants pay the bills?
Then your utility billing plan and your leases decide how savings are shared. See tenant meters and leases above.
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 retail center or office building?
Fill out the short form with your property details. There's no cost, and you don't need your bills to start.
What happens next
- You send your property 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, parking, meters, tenant setup, 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 property, your electric utility, a list of meters, the roof's age, 12 months of bills, and 15-minute interval data if you can download it from your utility account.
What do retail and office property owners ask about commercial solar?
Is solar worth it for a shopping center or office building in California?
Yes, for many retail and office properties using 50 kW or more. Flat roofs and large parking lots give solar plenty of room. California's business electric rates are among the highest in the country, so power you make yourself is worth more.
Can solar work if my tenants have their own meters?
Often, yes. Utility virtual billing plans can share one system's credits across tenant meters and common area meters at the same service point. The owner sets each meter's share and can change it as tenants turn over.
Who gets the solar savings under a triple-net lease?
Usually whoever pays the electric bill, which is often the tenant. If the owner pays for the system, the lease or an amendment should spell out how savings are shared. Review any lease changes with your attorney.
Do I need a battery with retail or office solar?
Not always. An office that winds down by late afternoon may do well with solar alone. Stores open into the evening and grocery sites with refrigeration usually need storage to cut the 4 to 9 PM peak charges.
Can solar go over our customer parking lot?
Yes. Solar carports can shade customer and staff parking while making power. Covering existing parking triggers California's CALGreen EV charging requirements, so plan chargers into the design. Carports also need clearance for delivery trucks and drive aisles.
Will a solar install disrupt my tenants or customers?
Some, but it can be planned around. Most rooftop and carport work happens while businesses stay open. The final hookup may need a short planned power shutdown, which can be scheduled outside business hours.
Should I replace my roof before going solar?
Often, yes, if it is near the end of its life. Panels are built to last for decades. Replacing the roof first can avoid removing and reinstalling the array for a reroof later.
Does California require solar on new retail and office buildings?
Yes, for most new ones. The 2025 Energy Code requires solar on newly built office, retail and grocery buildings for permits filed on or after January 1, 2026. Most also need a battery unless an exception applies.
What is the deadline for the federal solar credit on a retail or office building?
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. Multi-tenant projects need time for lease sign-offs, so start early and confirm details with your CPA.
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 bills for each meter. A tenant list and interval data from your utility account help too.
Not quite the right fit?
This page is for retail centers, stores and office buildings 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 →A tenant 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 retail or office?
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 →Stop Paying Peak Prices for Your Busiest Hours
Send your property 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.