# What a solar quote must show before you can judge it URL: https://solarrealcost.com/does-solar-pay/what-a-solar-quote-must-show Updated: 2026-09-18 Review: Reviewed by SolarRealCost Editorial Team, editorial review: primary sources checked and independently fact-checked The lines that belong on any solar proposal, the assumptions that quietly decide the payback, and the questions that produce real answers. Solar proposals are long and often beautifully designed, which is not the same as being comparable. Here is what has to be in one before you can judge it against another. - **System size in kW** and **price per watt**. - **Panel and inverter make and model**, not just a brand. - **Annual production in kWh**, and the **shading loss** assumed. - **Every payback assumption**, especially the **escalation rate**. - If financed: **APR, term, and the dealer fee as a dollar number**. ## The lines The [Department of Energy's homeowner guide](https://www.energy.gov/eere/solar/homeowners-guide-going-solar) is a good checklist to read alongside any proposal. System size in kW DC. Price per watt. Panel make, model and wattage. Inverter type, make and model. Estimated annual production in kWh. The shading loss assumed. Roof penetration warranty and its term. Workmanship warranty and its term. Any written production commitment. Whether a main panel upgrade is included. Permit and interconnection costs. And if financed, APR, term, total paid, and the dealer fee. Panel wattage also tells you how much roof the array needs; see [solar panel size](https://solarrealcost.com/does-solar-pay/solar-panel-size). Tool: [Cash, loan, lease or PPA](https://solarrealcost.com/does-solar-pay/tools/cash-loan-lease-or-ppa). The same system four ways over 25 years — escalators, dealer fees, who owns the tax benefit, and what happens when you sell. ## The assumptions that decide the answer A payback figure is only as good as what went into it. Three inputs do most of the work: **Production.** Check it against [NREL's PVWatts](https://pvwatts.nlr.gov/) for your own address. If the proposal is materially higher, ask what shading loss was assumed. **Escalation.** How fast electricity prices are assumed to rise. It compounds over twenty-five years and it is the easiest lever to make a weak deal look strong. **Any federal credit.** If it appears at all, the proposal is out of date — see [what happened to the federal solar credit](https://solarrealcost.com/does-solar-pay/what-happened-to-the-federal-solar-credit). **A monthly payment is not a price** A proposal that leads with a monthly figure and does not state the system price or price per watt has told you nothing you can compare. Ask for both. The [FTC's guidance](https://consumer.ftc.gov/articles/how-avoid-home-improvement-scam) on getting scope and price in writing applies here as much as to any home contract. ## Questions worth asking every installer What is the price per watt? What annual kWh are you putting in writing, and what happens if it underperforms? What shading loss did you assume? Who warrants the roof penetrations and for how long? Is any federal credit assumed anywhere in this proposal? If financed, what is the dealer fee as a dollar number? And who handles each step after signing, through the utility's permission to operate? Our guide to [solar panel installation](https://solarrealcost.com/does-solar-pay/solar-panel-installation) walks through those steps. ## Bottom line Get size, price per watt, production and assumptions on every proposal, then compare. The cost context is in [what solar costs to install](https://solarrealcost.com/does-solar-pay/install-solar-panels-cost). Start the Solar Check: https://solarrealcost.com/check ## Common questions ### What must be on a solar quote? System size in kW, price per watt, panel and inverter make and model, an annual production figure in kWh, the assumptions behind the payback, and the full financing terms if financed. ### Which assumption matters most? The electricity price escalation rate, because it compounds over twenty-five years and can make a poor payback look good. ### What is a production commitment? A written undertaking that the system will produce a stated minimum output, with compensation if it does not. Terms vary a great deal and some proposals have none at all. ### Should I accept a quote that only shows a monthly payment? No. Ask for the cash price and the price per watt. A monthly figure alone hides both the system price and the finance cost. ## Sources - [NLR (formerly NREL) Developer Network: PVWatts v8 API documentation](https://developer.nlr.gov/docs/solar/pvwatts/v8/) - [IRS: Residential Clean Energy Credit — not available for property placed in service after 31 December 2025](https://www.irs.gov/credits-deductions/residential-clean-energy-credit) - [FTC consumer advice: How to avoid a home improvement scam](https://consumer.ftc.gov/articles/how-avoid-home-improvement-scam) - [U.S. Department of Energy: Homeowner's guide to going solar](https://www.energy.gov/eere/solar/homeowners-guide-going-solar) - [CFPB: Issue Spotlight on solar financing (August 2024)](https://www.consumerfinance.gov/data-research/research-reports/issue-spotlight-solar-financing/)