A commercial solar feasibility study should tell an owner whether a specific property deserves a real procurement process—not merely whether panels fit on the roof. The useful answer combines interval load, tariff structure, usable roof or parking area, structural condition, electrical capacity, interconnection risk, ownership horizon and financing assumptions. It should finish with a go, redesign or stop recommendation that management can defend.
Do this before issuing a full commercial solar RFP or signing an installer proposal. A quick online estimate can screen an address; a feasibility study decides whether to spend time and money advancing the project.
What a commercial solar feasibility study must answer
A good study is a decision document. It does not need construction drawings, but it must resolve the questions that can change the investment case. The U.S. EPA recommends evaluating site viability, resource potential, system performance and cost before detailed design, contracts or equipment purchases in its renewable-energy feasibility guidance.
- Physical fit: How much unshaded, code-compliant area is actually usable after setbacks, drains, rooftop equipment, fire access and future tenant equipment?
- Energy fit: How much solar production can the property consume when it is generated, and how much would be exported?
- Economic fit: Which utility charges can solar reduce, which charges remain, and how sensitive is the result to escalation, degradation and financing?
- Asset fit: Will the roof, parking lot, electrical service and ownership plan support a 20-plus-year asset?
- Execution fit: What are the likely interconnection, permitting, insurance, lease, lender and construction constraints?
The final recommendation should separate assumptions from verified facts. “Satellite image shows 40,000 square feet” is an assumption. “Structural engineer confirmed this roof zone can accept the proposed loads” is a verified fact. That distinction prevents a screening model from masquerading as bankable engineering.
Collect these inputs before anyone models ROI
The quality of the model is mostly determined before the model opens. Start with 12 to 24 months of utility bills and, when available, 15-minute interval data. Capture rate schedules, demand charges, time-of-use periods, seasonal changes, taxes and riders. A blended dollars-per-kWh average hides the timing and demand components that often drive commercial savings.
Then assemble roof plans, roof age and warranty, structural drawings, one-line electrical diagrams, main service ratings, parcel and parking plans, tenant leases, planned load growth and the expected hold period. The EPA’s site-screening guidance specifically flags roof condition, electrical infrastructure, access, shading, permitting and interconnection as feasibility issues.
Production estimates should state orientation, tilt, shading and loss assumptions. The NREL PVWatts calculator is useful for an initial production estimate, but it does not inspect your roof, confirm structural capacity or guarantee an installer’s forecast. For solar-plus-storage, NREL’s REopt platform can test cost and resilience objectives using location, tariff and consumption inputs. If storage is material, compare the feasibility findings with our commercial battery storage owner guide.
Use decision math, not a single payback number
Illustrative example — run your own numbers. Assume a study screens a 400 kW rooftop system. These values are deliberately illustrative, not a quote, market benchmark or promise.
| Feasibility input | Illustrative assumption | Owner question |
|---|---|---|
| Year-one production | 600,000 kWh | Was shading and system loss modeled? |
| On-site use | 82% | What happens to exported energy? |
| Avoided energy value | $0.16/kWh | Does the tariff support this value by time period? |
| Demand-charge benefit | $18,000/year | Is this based on interval data or a guess? |
| Year-one O&M reserve | $7,500 | What monitoring, cleaning and service are included? |
The simplified year-one operating benefit would be:
(600,000 kWh × 82% × $0.16) + $18,000 − $7,500 = $89,220.
That number is only a starting point. The feasibility model should also show capital cost, tax or elective-pay eligibility, financing cost, degradation, inverter replacement, roof work, insurance, export compensation and the residual utility bill. Run downside cases for lower production, lower avoided rates, interconnection upgrades and delayed operation. Use our commercial solar savings calculator for an early screen, then replace every default with site evidence before approval.
Price the risks that proposals tend to postpone
Most weak feasibility studies are optimistic in the same places. They use the gross roof area, apply an average utility rate to every solar kilowatt-hour, ignore roof timing and assume interconnection is administrative. Owners should require a risk register with an owner, next action and budget allowance for every unresolved item.
- Roof and structure: If the roof needs replacement within the investment horizon, evaluate a coordinated project. Our solar roof planning guide explains the replace, recover or install-first decision.
- Electrical and interconnection: Identify service voltage, switchgear condition, transformer constraints and export limits. The Department of Energy’s distributed-energy interconnection checklist lays out the utility questions that belong early in development.
- Tariff and operations: Model the actual rate and expected operating hours. Planned electrification, EV charging, vacancies or new production lines can materially change the fit.
- Construction logistics: Account for crane access, shutdowns, tenant coordination, staging, fire lanes, warranties and working-hour restrictions.
- Ownership and exit: Test cash purchase, loan and commercial solar PPA structures against the organization’s capital constraints and hold period.
Federal incentive timing now belongs in the risk register, not in a footnote. IRS Notice 2025-42 states that Section 48E terminates for applicable solar facilities placed in service after December 31, 2027 when construction began after July 4, 2026. Review the current IRS construction guidance with qualified tax counsel and confirm prohibited-foreign-entity rules, wage and apprenticeship requirements, bonus eligibility and documentation before relying on a credit. Our 2026 commercial solar tax-credit guide provides an owner-level starting point.
Require deliverables you can use in procurement
A feasibility report should make the next step easier. Ask for an executive go/no-go recommendation; assumptions register; preliminary layout; production model; interval-load and tariff analysis; structural and electrical screening; interconnection pathway; budget range; incentive memo; financing comparison; sensitivity table; risk register; and a defined list of items requiring field verification.
It should also define a procurement basis: target system size range, acceptable export level, required equipment standards, roof and shutdown constraints, storage objectives, minimum monitoring requirements and proposal-comparison rules. That keeps bidders from solving different problems and presenting incomparable savings claims.
Before authorizing construction, convert screening assumptions into stamped engineering, utility confirmation, final pricing, contract terms and an executable schedule. A feasibility study reduces uncertainty; it does not replace due diligence or shift project risk away from the owner.
When a feasibility study is not the right next step
This work is not for every property. If the owner cannot provide utility data, controls neither the roof nor the meter, expects to sell immediately, has an active roof failure, or has no internal decision-maker, resolve those issues first. A detailed study can also be premature when a simple remote screen shows severe shading, too little usable area or a load too small to justify procurement.
Conversely, a free installer proposal is not a substitute when the site has multiple meters, complicated tariffs, aging switchgear, structural uncertainty, tenant allocations, storage requirements or a portfolio-level capital decision. In those cases, an owner-controlled feasibility scope helps keep the analysis independent of one vendor’s preferred system and financing product.
Ready for a defensible go/no-go answer? Send the property address, 12 months of utility bills, roof age and your ownership horizon. Commercial Solar Advantage can screen the site, identify the missing diligence and help you request comparable proposals. Start with how our process works, review a commercial solar case study, or request a project assessment and quote.