Commercial Solar Is a Long-Term Commitment
A commercial solar system represents a 25-year investment in your building. The installer you choose will handle the permits, coordinate with your utility, manage the installation, and be your point of contact if anything needs attention for years to come. Choosing based on price alone misses most of what matters.
These 12 questions help you evaluate whether a commercial solar installer is technically capable, financially stable, and genuinely aligned with your long-term interest.
12 Questions to Ask Every Commercial Solar Installer
1. Did you analyze my actual utility bills, including demand charges?
Commercial utility bills often include both energy charges (per kWh) and demand charges (based on peak kilowatt draw). A credible installer reviews your full billing structure before sizing a system — not just your total energy consumption. If they haven't asked for your bills, or haven't addressed demand charges, ask why.
2. Does your proposal include an energy efficiency review of my building?
An installer focused on selling the most panels possible has an incentive to size solar around your current, potentially inefficient load. An installer focused on your actual economic interest will identify whether efficiency improvements should precede or accompany the solar installation. Ask directly whether they assessed your building's energy efficiency before proposing a system size.
3. What production modeling tool did you use, and can I see the assumptions?
Production estimates for commercial systems should be based on your actual roof geometry, orientation, shading sources (HVAC equipment, parapets, adjacent buildings), and local solar data. Common tools include PVWatts, PVsyst, and Aurora Solar. Ask what was used and what shading adjustments were made.
4. Will your direct employees perform the installation, or subcontractors?
Larger commercial projects sometimes involve subcontracted labor. This isn't automatically a problem, but you should know. Ask about who manages the subcontractors, whether they're licensed for commercial electrical work in Illinois, and who is responsible for workmanship warranty claims.
5. Is a structural engineering analysis included?
Flat-roof commercial installations require calculating whether the roof structure can support the added load of panels and mounting hardware, plus wind and snow loads. Ask whether a structural engineering report is included and whether the roof was assessed for its remaining useful life relative to the 25-year system lifespan.
6. What is the realistic permitting and interconnection timeline?
Commercial projects in Illinois involve building permits, electrical permits, and utility interconnection approval — the interconnection process with ComEd or other utilities can take several months for larger commercial systems. Ask for a realistic timeline broken down by phase, not a best-case scenario.
7. What are the specific equipment models and their warranties?
Get specific panel manufacturer, model, wattage, and efficiency. Get the specific inverter model and its warranty. "Tier 1 panels" and "commercial-grade inverters" are marketing language, not specifications. Equipment manufacturers can go out of business; understand whether manufacturer warranties will be honored if that happens.
8. How should I approach the ITC and depreciation with my CPA, and what documentation will you provide?
The commercial Investment Tax Credit and MACRS depreciation are real benefits — but whether they apply to your business and how much they're worth depends on your specific tax situation. Ask what documentation the installer will provide for your CPA (cost segregation study, system cost breakdown, interconnection date records).
9. What monitoring system is included and what does ongoing service look like?
A commercial system generating electricity for 25 years will occasionally have issues — a failing inverter, a shading change from new construction, or monitoring anomalies that indicate a problem. Ask what monitoring is provided, how you'll be alerted to underperformance, and what the response process looks like.
10. What happens if your company closes in 5 or 10 years?
This is not an accusation — it's a reasonable question for any 25-year investment. Ask whether workmanship warranties are backed by insurance bonds or escrow accounts in addition to the company's own financial health. Understand what recourse you have if the installer is no longer in business when you need warranty service.
11. Can you provide references from commercial customers in Illinois with similar buildings?
Retail commercial references matter less than references from customers with similar building types, system sizes, and project complexity. A flat-roof 100 kW commercial project is different from a residential installation. Ask for commercial references specifically.
12. What additional costs might arise that aren't in this proposal?
Utility interconnection upgrades, structural remediation, electrical panel upgrades, roof work if the roof needs preparation, permitting fees beyond what's included — ask directly whether any of these could add cost to the project and under what circumstances.
What to Do With the Answers
You're not looking for perfect answers to every question — you're looking for installers who answer thoughtfully and honestly versus those who deflect, give vague assurances, or answer questions you didn't ask instead of the ones you did.
An installer who hasn't reviewed your utility rate structure, hasn't assessed your building's efficiency, and gives you a production estimate without showing you the assumptions is not ready to serve your long-term interest.
SPM approaches commercial projects with a load and efficiency assessment first, utility rate analysis second, and system proposal third. Learn about SPM's commercial approach or schedule a commercial site evaluation.