How to compare solar quotes (and spot the red flags)

Step 1: Make sure each quote has the essentials

A quote you can compare should list, in writing:

• System size in kW (DC), and the number, brand and model of panels.
• Inverter type and model (string, microinverters or optimizers).
• Estimated first-year production in kWh and the assumptions behind it (tilt, orientation, shading).
• Total cash price, plus every fee, and any financed price shown separately.
• What is included: permits, interconnection, monitoring, electrical upgrades, roof work, critter guards.
• Warranty terms for panels, inverter and workmanship, and who backs each one.
• An estimated installation timeline.

If an installer will not put these in writing, that alone is a reason to move on.

Step 2: Normalize the price

Price per watt = total cash price ÷ system size in watts. This removes the effect of system size. For reference, LBNL data put the median US cash price for residential systems installed in 2025 at about $3.00/W and the overall median at about $3.60/W. Our solar cost guide has more detail.

Cost per expected annual kWh = total price ÷ estimated first-year production. This captures equipment quality, orientation and shading, because what you are really buying is electricity, not watts.

Worked example: three quotes side by side

The arithmetic: Quote A is $27,200 ÷ 8,000 W = $3.40/W, and $27,200 ÷ 10,000 kWh = $2.72 per annual kWh. Quote B is $30,700 ÷ 9,600 W = $3.20/W.

Quote B looks best, but its production claim implies 1,396 kWh per kW on the same roof where the other two estimate 1,250. If PVWatts agrees with 1,250, Quote B's realistic output is 9,600 × 1,250 = 12,000 kWh, and its cost becomes $30,700 ÷ 12,000 = $2.56 per annual kWh. That is still competitive, but much less of a standout. Quote C is expensive because the financing cost is buried in the price: ask for its cash price before ruling it out.

Step 3: Compare equipment sensibly

Mainstream panels from established manufacturers perform similarly. Differences in efficiency matter mostly if your roof is small. Focus on:

• Panel warranty: look for a product warranty and a performance warranty that guarantees a stated share of original output after 25 years or so.
• Inverter approach: microinverters or optimizers help on partly shaded or multi-direction roofs; a single string inverter is often fine, and cheaper, on a simple unshaded roof.
• Inverter warranty length: it is often the first component to need replacement, so a longer warranty has real value.
• Battery-ready design: worth asking about if you may add storage later; see our battery guide.

Step 4: Read the installer's own warranty

Manufacturer warranties cover the hardware. The installer's workmanship warranty covers their work: roof penetrations, wiring, leaks. Terms vary widely, from a few years to 25. Ask who pays for labor if a panel or inverter fails under warranty, and whether roof leaks caused by the installation are covered. A long workmanship warranty means little if the company does not last, so consider how long the installer has been operating locally.

Step 5: Separate the financing from the system

Compare financing only after you have compared systems on a cash basis. For loans, ask for the APR, the term, any dealer or origination fee, and whether there is a prepayment penalty or a "re-amortization" step that raises payments if you do not make a lump-sum payment by a set date. For leases and PPAs, check the escalator and the end-of-term options. Our lease vs loan vs cash vs PPA guide covers each in depth.

Red flags to walk away from

• "Free solar" or "no-cost government program." Nothing is free; these usually describe a lease or PPA, sometimes with misleading framing.
• Pressure to sign today. Expiring "today only" discounts are a sales tactic. A fair offer will still be fair next week.
• Incentive claims you cannot verify. In the US, the homeowner solar tax credit (25D) ended for systems installed after 2025. Any rep still promising it on a new owned system is misinformed or misleading you. Check current programs on our incentives page.
• Savings based on a high assumed rate increase. Projections that assume utility rates rise 5% or more every year for 25 years can make a weak deal look strong. Ask to see the figures at 0% and 2%.
• Only a monthly payment quoted. If you cannot get a total price and a cash price, you cannot compare.
• Production far above independent estimates. See the Quote B example above.
• Oversizing under low export rates. If your utility pays little for exports, a system much larger than your daytime use can lower your return.
• No license or insurance details. Ask for the contractor's license number and proof of insurance and check them with your state or provincial licensing body.
• Signing on a tablet without a copy. Get the full contract to review, and know your cancellation window.

Where to get comparable quotes

Ask each installer for the same thing: the same target system size or annual output, a cash price, and an itemized scope. If you would like to start with a few local options, you can request free quotes from vetted installers and then run them through the steps above.

This guide is general information, not financial, tax or engineering advice. Prices and incentives change — confirm with qualified local professionals and official program sources. See our methodology and disclosures.