How to Compare Solar Quotes in Illinois: 8 Lines on the State Disclosure Form That Do the Work for You
To compare solar quotes in Illinois, ask each company for its Illinois Shines disclosure form and compare those, line by line. Any project that goes through Illinois Shines comes with this state form. The company has to fill in every field and hand it to you, and you have to sign it before you sign the contract. Every form uses the same layout, and the 2026 version has the same sections in the same order no matter who prepares it. Eight lines on it do most of the comparing for you.
Sales decks are where quotes get hard to compare. One company shows 25 years of savings, another shows 20, one assumes rates climb 4% a year, and one still knocks off a federal tax credit that ended last December. The state form cuts through that. Here's how I'd read two of them side by side.
The 8 lines to line up
| Line on the disclosure form | What to compare | Why it matters |
|---|---|---|
| Total amount paid (lease) or total amount paid including purchase price (purchase) | The full dollars over the contract | Deposits, fees and any escalator are already in it |
| Project size, kW DC and kW AC | Divide price by DC watts | Shows price per watt, the only fair cash comparison |
| Estimated first-year production, kWh | Production per kW of size | Shows whose design (or whose assumptions) is stronger |
| Estimated capacity factor, first 15 years | The percentage itself | The state built this line to compare designs |
| Illinois Shines incentive and the amount passed to you (purchase) | Dollars passed through | Different companies pass on different amounts |
| Distributed Generation rebate and storage rebate, and "who keeps" them | Customer vs. company | That's $300 per kW of DC on a home system through 2029 |
| Warranties, repairs and production guarantee | Who covers what, for how long | This is what you're buying when something breaks |
| If you move / early termination | Transfer terms and payoff | Decides how a home sale goes |
Sources for every line are at the bottom. The form layout comes from the June 1, 2026 sample lease and purchase disclosure forms.
Why the state form beats the sales proposal
The Illinois Power Agency's rules say the form must be complete and accurate "before presentation to the customer," and it can't just point you to the contract or an attachment for a required answer. If the offer includes a battery, the battery's costs and fees have to be on it. In person, the salesperson has to walk you through the whole form and let you ask questions.
Here's the part I like best. The form's savings estimate runs on assumptions the program sets, not the salesperson. Illinois Shines publishes the retail and supply rates its portal uses for ComEd and Ameren. In the state's sample (a ComEd customer), the form assumes 75% of the solar power is used in the home, valued at 15.552¢ per kWh, with the rest sent to the grid at 9.1¢. It runs low, medium and high cases with electricity prices climbing 0.5%, 1.7% and 2.5% a year. Right under the numbers it says, "Solar companies may use different assumptions in documents they produce."
In plain English, the glossy proposal can say whatever the company likes. The state form can't. Two quotes for the same house on the same utility should be valued the same way on the form. When a proposal's savings number is much bigger than the form's medium estimate, look at the assumptions behind it.
Buying: price per watt, then the incentive pass-through
Total price isn't the comparison. System size is. Divide each quote's price by its DC size in watts:
- Quote A: 7.0 kW DC for $19,600 = $2.80 per watt
- Quote B: 7.6 kW DC for $25,080 = $3.30 per watt
Quote B looks like more system, and it is, but you're paying 50¢ more per watt for it. On 7,600 watts, that's $3,800. For reference, our own average is about $2.60 per watt before incentives, and the customer keeps the incentives. Other companies price differently. The per-watt number is a way to spot the outlier, not a law.
Then look at the incentive section. On a purchase, the form shows the full Illinois Shines incentive the company expects to receive and the amount it'll pass on to you. In the state's sample, the company expects about $18,298 and passes $12,000 to the customer, roughly 66%. Illinois Shines' own guide says it plainly: "Different Approved Vendors may pass through different amounts of the Illinois Shines incentive to the customer." Two quotes with the same price can be thousands of dollars apart on this one line. The REC calculator shows what the incentive is worth for your system size, and the 2026-27 REC price post explains the tables.
If you're financing, the form only says to consult your financing agreement. That's where dealer fees hide, and I've written up how a "1.99%" loan can really cost 4.4%.
Leasing: turn the total into cents per kWh
Most of my customers lease, and lease quotes are easier to compare than people think. The lease form has a line called "Total amount paid, including lease payments and above fees, for duration of lease." Any deposit, maintenance fee or annual escalator is already in that number.
Divide it by how much power the system should make over the lease:
- Take the first-year production estimate (kWh).
- Multiply by the lease length in years.
- Shave about 0.5% a year for panel aging, the same rate the state form uses.
The state's sample lease is $27,250 total over 20 years for a system estimated at 12,000 kWh in year one. That's about 228,900 kWh over the term, or about 11.9¢ per kWh. Do that for every lease quote and you'll know which one is the cheaper power, no matter how the monthly payment is dressed up. Then compare it to what you pay now on the Ameren or ComEd rate pages. I go through monthly payment ranges in what a solar lease costs per month.
After the price, compare what happens when something goes wrong. The lease form has a line for repairs ("fixing malfunctioning project"), a line for a production guarantee, and a line for whether a new homeowner can take over the lease. A $5 cheaper payment with no repair coverage is a bad trade.
The capacity factor line catches inflated production
Every form shows an "estimated capacity factor for the first 15 years." Illinois Shines defines it as annual production divided by the system's size times 24 hours times 365 days, averaged over 15 years with 0.5% yearly aging. The state's sample shows 17.4%, with "partial shade in morning from neighbor's tree" written underneath.
You don't need to know the formula. If three companies look at the same roof and one claims a noticeably higher capacity factor than the others, ask why. Either it's a better design (better panel placement, less shade) or it's a rosier production estimate. Higher production makes every savings number look better. Our panel count guide shows what PVWatts expects in ten Illinois towns, which makes a good reality check.
The tax-credit trap in old quote guides
Several national "how to compare solar quotes" pages still list the 30% federal tax credit as an Illinois incentive. For a system you buy for your own home, that credit isn't available for systems placed in service after December 31, 2025. If a quote subtracts 30%, redo the math without it. The rebate that's still real is the utility's $300 per kW of DC capacity from ComEd or Ameren through 2029 (it drops to $250 in 2030). On the form, check the line that says who keeps it. My rebate explainer has the details.
Before you sign
- You have at least three calendar days to cancel. The form says you can rescind and get your deposit back within the period in your contract or the law, "which cannot be less than three calendar days." Here's how to get out of a solar contract.
- Take your time. The form itself says you "should take whatever time you need to shop around."
- Read the roof-leak warranty line. It's separate from the panel warranty. I explain why in do solar panels cause roof leaks.
- If something goes wrong, Illinois Shines takes complaints at complaints@illinoisshines.com or (877) 708-3456.
If you've got two or three quotes on the table, send them over. I'll go through them line by line with you, even if ours isn't one of them. Call (618) 217-2001 or reach out here. To see what solar could save on your bill first, try the savings calculator.
Sources
- Illinois Shines Solar Project Lease Disclosure Form, sample (June 1, 2026) — Illinois Power Agency / Illinois Shines
- Illinois Shines Solar Project Purchase Disclosure Form, sample (June 1, 2026) — Illinois Power Agency / Illinois Shines
- Consumer Protection Handbook and DG Contract Requirements, 2026-27 program year (IPA Appendix H-1; Contract Requirements published April 17, 2026) — Section V, Standard Disclosure Forms and Requirements for Contract Execution
- Illinois Shines Disclosure Form Resources and the DG purchase disclosure form guide — Illinois Shines, accessed November 5, 2026 (capacity-factor definition; incentive pass-through)
- 220 ILCS 5/16-107.6 — Illinois Public Utilities Act, distributed generation rebate ($300 per kW; $250 from January 1, 2030)
- IRS, Residential Clean Energy Credit — page updated July 4, 2026 (not available for property placed in service after December 31, 2025)
- Illinois Shines, "Reminder About Marketing Federal Tax Credits" (Aug. 7, 2026)
