Commercial solar, starting with your actual tariff

What is commercial solar?

Commercial solar is a grid-tied generation asset sized against a business tariff rather than a household bill, and the analysis is different in kind, not just in scale. Commercial rates commonly bill demand - your highest measured power draw in a period - separately from consumption, and an array reduces consumption far more reliably than it reduces peak demand. Scoping starts with twelve months of interval data and the rate schedule, then works through roof structure, remaining lease term and the ownership structure that will hold the asset.

Signs you need commercial solar

• You have large, flat or low-slope roof area over a single-storey footprint - warehousing, distribution, light manufacturing, retail, cold storage
• Your load profile is daytime-heavy and matches the production curve without needing storage to shift it
• You occupy the building as owner, or hold a long lease with the right to make structural alterations
• Refrigeration, compressed air, process equipment or HVAC drive a consistently high daytime baseline
• You have carport-capable parking, ground area or canopy structures that could host an array without touching the roof at all
• You are already re-roofing, so structural assessment and membrane detailing can be handled once rather than twice
• Procurement or reporting commitments make on-site generation a stated business objective rather than purely a cost decision

Seeing something not on this list? Browse solar problems by symptom →

How commercial solar actually works

1. 1

   Interval data and rate schedule analysis, before any design

   The starting point is twelve months of interval data and your actual rate schedule, not an annual spend figure. The analysis separates consumption charges from demand charges, identifies when your peaks occur, and establishes how much of them fall inside daylight hours.

   Watch forA proposal built from your total annual bill divided by kilowatt-hours. That blends demand and consumption into an average that does not exist on any tariff, and it systematically overstates what an array will save. Ask which rate schedule the model uses and to see the demand component separated out.

2. 2

   Roof structure, condition and remaining life

   A commercial roof assessment covers structural capacity for the added dead load and any wind uplift or seismic requirement, plus the condition and remaining life of the membrane. Ballasted, mechanically attached and adhered systems each interact differently with racking.

   Watch forA membrane with fewer years left than the array's design life, and a roofing warranty that does not survive third-party attachment. Get the roof manufacturer's position in writing, use an installer their warranty programme accepts, and if the roof is ageing, re-roof first - removing and re-setting a commercial array later is a substantial project in its own right.

3. 3

   Site control: ownership, lease term and consents

   The array outlives most commercial leases. Where the building is leased, the project needs landlord consent, a clear position on who owns the equipment at lease end, and a decision on who receives the bill savings - which in a triple-net structure may not be the party funding the work.

   Watch forA project modelled over a term longer than your security of tenure. Settle removal obligations, ownership at expiry and any make-good clause before signing, not during a lease negotiation years later.

4. 4

   Interconnection study and utility approval

   Commercial interconnection is a heavier process than residential. Depending on system size and local circuit conditions, the utility may require studies, protective equipment, or upgrades to the distribution network - and the cost of those can be assigned to the project.

   Watch forInterconnection treated as a formality in the schedule. It is frequently the longest and least predictable item, and a required network upgrade can materially change the economics. Ask what the utility's queue and study timeline currently looks like for a system of this size in this territory.

5. 5

   Ownership and financing structure

   The project can be owned outright, financed, or held by a third party under a lease or a power purchase agreement in which the developer owns the asset and sells you the output. Ownership determines who takes the tax and depreciation benefits, who carries the maintenance obligation, and what happens at end of term.

   Watch forThe escalator in a long-term PPA, and the buyout and assignment terms. A rate that starts below your utility price but rises annually can invert if utility prices do not rise as assumed. Price the whole contract term, and check whether the agreement can be assigned if you sell the building. Have a qualified tax adviser confirm what your entity can actually use before any benefit is priced into a model.

6. 6

   Storage and demand management, assessed separately

   If demand charges are a large share of your bill, storage with a demand-management controller - or simply shifting a controllable load - may deliver more than additional panels. This is a distinct analysis from the consumption saving and should be modelled on its own.

   Watch forDemand-charge reduction claimed from an array alone. Peak demand can be set by a brief event on a cloudy afternoon or outside daylight entirely. Ask to see the demand analysis separately from the consumption analysis, with the assumptions stated.

7. 7

   Construction, commissioning and operations handover

   Construction is sequenced around your operations, with roof access, safety and any shutdown windows agreed in advance. Commissioning should produce measured results, as-built drawings, and a defined operations and maintenance arrangement with response times.

   Watch forNo operations and maintenance agreement, or one with no response-time commitment. On a commercial asset, an undetected fault is a monthly financial loss, and the party responsible for noticing should be named in a contract.

What does commercial solar cost?

Commercial projects are priced per watt and fall well below residential rates at scale, but interconnection studies, structural work, roof remediation and switchgear can move a budget substantially. Confirm the current federal and state incentive and depreciation position with a qualified adviser before it is built into any model.

See the full commercial solar cost guide - by material, size and region →

If the number is the problem, here are the ways people pay for it →

Solar tools and calculators → Size a commercial array against interval data rather than an annual bill.