TL;DR: Learning how to compare solar quotes comes down to one early step: convert every proposal to a price per watt before incentives, so you are comparing the same thing. Then check the lines that actually change what you pay – cash price versus financed price, loan dealer fees, escalator clauses, and the assumptions behind the production estimate. Most homeowners sign the quote with the lowest monthly payment, which is often the most expensive system on the table.
Three quotes, three different systems, three different finance structures, and three salespeople telling you the monthly payment is what matters. Comparing them by monthly payment is exactly how people end up paying several thousand dollars more than they needed to.
Here is a method that takes about an hour, and the nine things worth checking in every proposal.
Step One: Normalise Everything to Price Per Watt
Before you compare anything else, convert each quote to a single number: the total system cost before incentives, divided by the system size in watts.
A $25,000 system at 8,000 watts is $3.13 per watt. If a second quote is $22,000 for 6,600 watts, that is $3.33 per watt – so the cheaper-looking quote is actually the more expensive system.
This one calculation exposes more bad deals than anything else on the list, because it removes the two things sales reps use to blur the comparison: monthly payment framing and system size.
If the annual cost and the system size vary between quotes, our guide to what drives solar panel installation cost explains the components worth comparing.
The Nine Things to Check in Every Quote
1. Price Per Watt, Before Incentives
Use the pre-incentive figure. Quoting the price after tax credits makes cheap systems look cheaper and hides differences, especially when two quotes assume different credit amounts.
2. Cash Price Versus Financed Price
This is the single most important line, and it is the one most often left out.
Solar loans usually include a lender fee that is built into the system price rather than shown as interest. That means the financed price for a system can run noticeably higher than the cash price for the same equipment – often in the region of 15 to 30 percent. Ask each company for both numbers, in writing.
If a rep cannot or will not give you the cash price, treat that as a signal rather than an oversight. Our overview of solar loans and financing explains how these fees work.
3. Loan Terms, Not Just the Payment
For any financed quote, ask for the APR, the term length, the total amount repaid over the life of the loan, and whether there is a prepayment penalty. A 25-year loan with a low payment can cost far more in total than a 12-year loan with a higher one.
4. Escalator Clauses
Leases and power purchase agreements often include an annual escalator, meaning your payment rises every year. It is commonly in the 1 to 3 percent range. Over a 20-year term that compounds, and it is usually mentioned in the fine print rather than the presentation. Our breakdown of leasing solar panels covers how these contracts compare with owning.
5. The Assumptions Behind the Production Estimate
Every quote includes an estimate of how much the system will generate. That number depends on assumptions: shading, roof orientation, local weather data, panel degradation, and whether anyone actually measured your roof or worked from satellite imagery.
Two quotes with different production assumptions can show wildly different savings from identical equipment. Ask what the estimate is based on, and check whether a shading study was done on site.
6. The Exact Equipment
Get the panel brand, model and wattage, plus the inverter type and model, written into the contract. “Tier 1 panels” is not a specification – it is a category.
Also ask what happens if that exact equipment is unavailable at install time. Substitutions should be equal or better, and that clause should be in writing.
7. Warranty Terms and Who Honours Them
You are dealing with three separate warranties: panels, inverter, and the installer’s workmanship. The workmanship warranty is the one that protects you against roof leaks and bad wiring, and it is the one that vanishes if the installing company closes.
Ask how long the workmanship warranty runs, what voids it, and whether it is transferable if you sell the house.
8. What Is Not Included
Quotes are compared on the headline number, but the expensive surprises live outside it. Common exclusions worth checking:
- Critter guard under the array
- Electrical panel upgrade, if your panel is full
- Trenching for ground or detached installations
- Roof repair or re-flashing
- Monitoring hardware or a consumption meter
- Permit and interconnection fees
- Removal and reinstallation if the roof is replaced later
An extra $2,000 of excluded work turns a cheap quote into an expensive one.
9. The Company Behind the Quote
Check how long the company has operated under that name, whether installation crews are in-house or subcontracted, whether they have a physical location in your area, and whether the licence number on the quote is current. The questions worth putting to each company are set out in our guide to choosing a solar installer.
Build a One-Page Comparison Sheet
Put each quote in a column and these fields in rows. Filling this in takes twenty minutes and makes the decision obvious.
| Field | Quote A | Quote B | Quote C |
|---|---|---|---|
| System size (kW) | |||
| Cash price | |||
| Price per watt (cash) | |||
| Financed price | |||
| Loan APR and term | |||
| Estimate of annual production | |||
| Panels and inverters | |||
| Workmanship warranty | |||
| Exclusions in writing | |||
| In-house or subcontracted crew |
Red Flags Worth Walking Away From
- A price that is only valid today, or “signs today” pressure
- No site visit before quoting
- Refusal to give the cash price or the price per watt
- A production estimate with no shading analysis behind it
- A monthly payment presented as the headline number
- Equipment described only in vague tier language
- No physical address or licence number on the proposal
When the Numbers Are Close
If two quotes land within a few percent per watt, price is no longer the deciding factor. At that point, choose on the workmanship warranty, whether crews are in-house, who answers the phone in year seven, and how the company handled your questions during the sales process. Those are the things that decide whether owning solar is a good experience or a long argument.
FAQ
How many solar quotes should I get?
Three is the practical minimum, and they should include at least one local company. Two quotes leaves you comparing rather than testing the market, and five makes the comparison harder without adding much information.
Why are financed solar prices higher than cash prices?
Because the lender charges a fee that the installer builds into the system price rather than showing as interest. That is why the same system can have two very different prices depending on how you pay.
What is a good price per watt in 2026?
It varies by state and system size, but as a rough reference, residential systems commonly quote in the low $2 to mid $3 per watt range before incentives. Anything well above that deserves a written explanation.
Should I compare solar quotes by monthly payment?
No. Monthly payment hides the system size, the loan term and the fees. Compare price per watt first, then look at the payment only after you have chosen a system and a finance structure.
What if one quote is much cheaper than the others?
Check what is missing rather than assuming you found a bargain. A quote far below the others usually has smaller or lower-grade equipment, a shorter workmanship warranty, exclusions that appear later, or a company without in-house crews.
Related: How to Choose a Solar Installer – Questions to Ask Before Hiring
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