How to Compare Solar Proposals: A Plain-English Checklist for Homeowners

Start with the same problem, not three different sales pitches

A useful solar comparison begins with the home’s actual electricity use, roof and utility rules. Ask each company to show the bills or annual kilowatt-hours used to size the system. Then confirm that every proposal is using the same basic goal: offsetting part of your annual use, covering as much usable roof as practical, or adding a battery for a defined backup need.

Do not compare two proposals by panel count alone. Panels have different power ratings, and two layouts can produce different amounts because of roof direction, shade, tilt and equipment losses. Compare system size in kilowatts, estimated first-year production in kilowatt-hours and the assumptions behind that estimate. Tower Solar’s estimate calculator can provide an independent starting point, but it is still an estimate and should be checked against the installer’s site survey and utility data.

Separate the cash price from the financing

Ask for the total cash price before discussing the loan payment. Then ask for the total amount financed, annual percentage rate, term, payment schedule and total of payments. A low monthly payment can come from a long term, a large fee added to the principal, or an expected future payment that is easy to miss.

The Consumer Financial Protection Bureau reported in 2024 that some solar-specific loans included markups and fees that increased the principal by 30% or more above the cash price. That finding does not mean every solar loan has that markup. It does mean homeowners should demand both numbers in writing and ask why they differ. Compare the installer’s financing with at least one bank or credit-union option when practical.

If a proposal assumes that you will use an incentive or tax refund to make a large early payment, ask what happens if you do not receive that amount or receive it later than expected. Tax eligibility depends on current law and individual circumstances. A salesperson should not treat a tax credit as guaranteed cash or give personal tax advice.

Test the production and savings assumptions

The proposal should state the system’s expected annual electricity production, the weather data and software used, shading assumptions, equipment losses and expected degradation over time. Ask whether the installer performed an on-site roof and shade review or relied only on satellite imagery. Also ask whether the production figure is an estimate or backed by a written guarantee, and how any guarantee is measured and enforced.

Savings depend on more than production. They also depend on the utility’s current rate design, fixed monthly charges and the value assigned to electricity sent back to the grid. Future utility rates are difficult to predict. The Federal Trade Commission specifically warns consumers to examine the rate-growth assumptions used in long-term solar comparisons. A proposal should show what happens if utility rates rise more slowly than assumed, not just its best-looking scenario.

In Pennsylvania, New Jersey and Florida, utility and program rules differ by service territory and can change. Require the proposal to identify the exact utility tariff, export-credit rule and interconnection process it assumes. Verify those items with the utility or regulator rather than relying only on a sales presentation.

Know what you will own

A cash purchase or loan normally leads to homeowner ownership, subject to the financing contract. A lease gives you use of the equipment while another company owns it. Under a power purchase agreement, or PPA, you buy the electricity the system produces under a long-term contract. The price, payment increases, maintenance responsibility and end-of-term choices differ among these arrangements.

Ask who owns the panels, renewable-energy certificates and any tax or program benefits. Ask whether a lien or other security interest will be recorded, how the agreement affects refinancing, and what happens when the home is sold. For a lease or PPA, review transfer requirements, buyer credit approval, early-termination charges, removal costs and any annual price escalator.

Read the equipment, roof and warranty details

A complete quote should identify the panel, inverter, mounting system and battery model when applicable. It should state who provides the product warranty, who covers installation workmanship and who responds if the roof leaks or the system stops reporting. Manufacturer coverage and installer workmanship coverage are not the same thing.

Confirm the roof’s age and condition before installation. If the roof may need replacement soon, compare the cost and risk of doing that work first with the cost of removing and reinstalling panels later. Ask who is responsible for permits, engineering, inspections, utility applications and unexpected electrical upgrades, and whether those costs are included.

Watch for pressure and claims that are too clean

The Federal Trade Commission advises consumers to avoid companies claiming that government programs cover the entire cost, pretending to represent the government or utility, demanding large advance payments, or rushing customers to sign on an electronic tablet without showing the full agreement. “Free solar,” “no more electric bill” and “sign today to keep the program” require verification, not excitement.

A good installer should give you time to review the complete contract, answer questions in writing and explain cancellation rights without hiding pages or links. Check the company’s required state and local licenses, insurance, complaint history and references. Certification can support competence, but it does not replace contract review or license verification.

Use a one-page comparison

For each quote, record: system size; first-year production; cash price; cash price per watt; financed amount; APR; term; total payments; payment changes; ownership; equipment models; roof work; warranties; production guarantee; utility assumptions; permits and interconnection costs; cancellation terms; home-sale process; and the responsible service company.

Reject any comparison that leaves important cells blank. The cheapest price is not automatically the best value, and the smallest monthly payment is not automatically the lowest cost. A sound choice is the proposal whose assumptions you can verify, whose contract matches the sales claims and whose risks you can afford.

Use Tower Solar’s calculator to create a neutral estimate, review the Resources section for official forms and utility information, and request a human review when you want a second look at a proposal. Do not send sensitive financial documents unless the upload method and privacy terms are clear.