1. Normalize system and price
Record DC system size in kW, panel count and wattage, cash price, battery price, and excluded work. Divide the solar-only cash price by DC watts for a basic price-per-watt comparison. Do not compare one cash offer with another financed offer.
2. Expose financing cost
Write down the financed amount, APR, term, monthly payment, dealer or origination fees, prepayment terms, and total scheduled payments. Ask for the cash price of the identical system. A low promotional APR may be paired with a higher financed principal.
3. Verify production
Compare estimated first-year kWh, not only percentage offset. Ask what weather dataset, shade measurement, orientation, losses, and degradation were used. Verify that the utility usage in the model matches your bills.
4. Confirm people and obligations
Identify the legal seller, installer, electrician, lender, equipment manufacturers, monitoring provider, and warranty administrator. Read cancellation, roof, lien, transfer, arbitration, and change-order terms before signing.