Short answer: put every quote on the same footing: price per watt (total price ÷ system watts), estimated yearly production (kWh), equipment brands and models, and warranties. The U.S. average was about $3.36 per watt in Q3 2026 (Solar.com). Get at least three quotes; a quote far above average needs a good reason.
The 8 lines to check
| Line | What to look for |
|---|---|
| System size (kW DC) | Panel count × panel watts. Should match your usage goal; see how many panels you need. |
| Total price and price per watt | Cash price before incentives; compare $/W across quotes. |
| Year-1 production (kWh) | Check it against NREL’s PVWatts for your address. |
| Panels | Brand, model, wattage. Most home panels quoted in late 2025 were 400-460 W (EnergySage). |
| Inverter | String, string with optimizers, or microinverters; see which is better. |
| Warranties | Panel product and output (often 25 years), inverter, and workmanship/roof penetration. |
| Savings estimate | Which electricity rate, yearly rate increase and export credit did they assume? |
| Financing | Loan rate, term, dealer fee, or lease escalator. |
Worked comparison
| Quote A | Quote B | Quote C | |
|---|---|---|---|
| Size | 7.2 kW | 7.6 kW | 6.8 kW |
| Price | $23,000 | $30,400 | $20,400 |
| Price per watt | $3.19 | $4.00 | $3.00 |
| Year-1 production | 9,400 kWh | 9,500 kWh | 9,800 kWh |
| Cost per first-year kWh | $2.45 | $3.20 | $2.08 |
Illustrative numbers. Quote C looks best, but its production is high for a smaller system: check that estimate in PVWatts before trusting it. Quote B needs to justify its premium (better equipment, a battery, roof work).
8 red flags
- “Free solar” or “government program” pitches that turn out to be leases.
- Federal tax credit still listed for a homeowner purchase. It ended for systems installed after Dec. 31, 2025 (IRS).
- Savings that assume big yearly rate increases (above about 3-4%) without saying so.
- Production estimates far above PVWatts for the same size, tilt and direction.
- Lease escalators above 3% a year (EnergySage suggests 0-1%).
- Big dealer fees hidden in a “low-rate” loan; ask for the cash price.
- No roof assessment on an older roof. See should you replace your roof first.
- Same-day signing pressure or a short cancellation window.
Questions to ask every installer
- Who does the installation: your own crew or a subcontractor?
- Who handles permits, inspection and utility interconnection, and how long do they take?
- What happens if production falls short of the estimate?
- Who services the system if your company closes?
FAQ
Is the cheapest quote the best? Not always. Compare equipment, warranties and the installer’s track record, then price per watt.
Can I negotiate? Yes. Showing a competing quote’s price per watt often helps.