Solar quote comparison checklist

The contract details, assumptions, and installer questions that make competing solar proposals comparable.

Sources reviewed: 2026-10-06

First, make every proposal comparable

Put every proposal into the same worksheet: DC system size, AC inverter capacity, panel and inverter models, first-year production, gross cash price, incentives, financing terms, batteries, and optional work. The U.S. Department of Energy homeowner guide recommends obtaining and comparing multiple bids from qualified installers.

Calculate the solar-only gross price per watt. Exclude batteries, roofing, and unrelated electrical work, but keep those line items visible. Compare the result with the detailed method in How much do solar panels cost?.

Worked example: two quotes that are not equivalent

Quote A offers 7.2 kW for $21,240 cash and predicts 10,000 first-year kWh. That is $2.95 per watt. Quote B offers 8.0 kW for $22,800 and predicts 10,100 kWh. That is $2.85 per watt, but its production per installed kW is lower. Before choosing B, ask whether roof placement, shade, inverter clipping, or different loss assumptions explain the result.

Use the Solar Cost Atlas calculator with each quote's gross cost and production. Keep utility-rate and export assumptions identical so the comparison isolates differences in the proposals.

Verify the production estimate

Ask for the model, weather data, roof planes, azimuth, tilt, shade, inverter ratio, and total system-loss assumption. NREL's PVWatts calculator provides an independent preliminary check. A sales proposal and PVWatts can reasonably differ, but the installer should explain why.

Compare annual and monthly production, not only the claimed percentage of bill offset. Confirm whether the estimate reflects current annual kWh use and whether future loads were added. Review How to estimate solar system size from your electric bill before accepting an offset claim.

Separate equipment and workmanship coverage

Record product, performance, inverter, battery, roof-penetration, and installer workmanship warranties separately. Manufacturer warranties do not necessarily pay labor to diagnose, remove, ship, or reinstall equipment. Ask who receives the service request, expected response times, trip charges, and what happens if the installer stops operating.

Compare financing and ownership

For new property placed in service after December 31, 2025, use $0 federal Residential Clean Energy Credit. The IRS excludes these installations, including battery property. If a proposal assumes a federal-credit loan paydown, request a corrected payment schedule. Valid credits from earlier qualifying installations and unused carryforwards are separate tax-return matters under the Form 5695 instructions, not a discount on a new project.

Request a cash price even if financing. For loans, record APR, term, financed amount, total payments, dealer fee if disclosed, prepayment rules, and whether a tax-credit re-amortization is assumed. For leases or power purchase agreements, record ownership, starting payment or energy rate, escalator, term, transfer rules, production guarantee, and end-of-term options.

The Federal Trade Commission advises consumers to understand total costs, warranties, promises of savings, contract cancellation, and what happens when selling the home. Do not rely on verbal promises that are absent from the signed agreement.

Check installer and project responsibilities

Verify the legal contractor name, license where applicable, insurance, subcontractors, references, and complaint history using the relevant state licensing authority. Confirm who handles permits, utility interconnection, inspections, monitoring setup, incentive paperwork, and permission to operate.

Review your local market before signing. The California solar guide, New York solar guide, and Texas solar guide illustrate why export rules and incentives must be checked locally. Browse all published state solar guides and then confirm details with the serving utility and state agencies.

Read the contract, not just the proposal

Confirm scope, exclusions, equipment-substitution rights, payment milestones, start and completion conditions, change orders, cancellation rights, dispute terms, roof-leak responsibility, removal and reinstallation costs, and the process if the utility rejects or reduces the proposed system. Keep a complete signed copy and all attachments.