How to read a solar proposal: the 7 numbers you have to find

You read a solar proposal by hunting for seven numbers: estimated month-by-month production, the percentage of your usage it covers, price per watt, the escalator (if it is a lease or PPA), warranties listed separately, the utility’s minimum charge in the projection, and which tax credit was deducted. If any is missing or buried, the proposal was not written for you to understand it. Here is where to find each one and what a reasonable value looks like.

1. Does it show month-by-month production in kWh?

It is the most important number and the one most often left out. Monthly production comes from a simulation (NREL’s PVWatts or equivalent software) with your address, orientation and tilt, and should appear as a table of 12 values in kWh. With it you can compare against your 12 bills and, after installation, against the monitoring.

If the proposal only has an annual number (“produces 15,000 kWh a year”), ask for monthly. If they cannot provide it, there is no simulation behind it; there is a salesperson’s estimate.

2. What percentage of your usage does it cover?

It should sit between 100% and 115%, and we design at ~110%. The offset is estimated annual production divided by your real annual usage. A 100% design has no margin for a hot summer; above 115%, year-end surplus is paid at the generation rate and does not cover the cost of the extra panels. With FPL, going past 10 kW also moves you to Tier 2 with a $400 fee and insurance. How to verify the size is in how many panels do I need.

Check that the usage they used is yours: add up the kWh from your 12 bills. If they used “the area average,” the offset is fiction.

3. What is the price per watt?

Divide the total price by the system’s DC watts (kW × 1,000). In Florida, cash, EnergySage reports $2.12/W and SolarReviews $2.71/W (both September 2026); financed, SolarReviews reports about $3.25/W. Those are the market ranges.

If price per watt is not shown, calculate it yourself. If the cash and financed prices are “the same,” the lender fee is buried in the principal. Details in solar cost in Florida.

4. Is there an escalator, and how much?

In a lease or PPA, look for the word “escalator” or “annual increase.” Solar.com reports 2.9% a year is common, and that at that pace a $150 payment becomes about $305 in year 25. An honest proposal shows the payment table year by year; one that only shows “total 25-year savings” is using the electricity rate escalator (which nobody guarantees) to cover the escalator on your payment (which is in the contract). The four ways to pay are compared in ways to get solar compared.

5. Are the warranties separated and named?

Three should appear: panel product (25 years is the standard today per EnergySage), panel performance (around 85% at 25 years), and inverter (10-12 years string, 25 for microinverters or optimizers). Plus a fourth, the installer’s workmanship, with its own term. “25-year warranty” without saying which of the four is a red flag. Details in panel types and warranties and string inverters vs microinverters.

6. Does the projection include the minimum charge?

If the projected “with solar” bill is $0, the minimum charge is missing. FPL charges a $25 monthly minimum base bill per its rate document; Duke and TECO have their own. A projection that omits it inflates savings every month for 25 years. Read how much solar really saves.

7. Which tax credit did they deduct?

If it is a 2026 purchase and they deduct “30% federal,” it is wrong. The IRS confirms the 25D credit does not apply to expenditures after December 31, 2025. In a lease or PPA, the 48E credit is claimed by the owning company and should show up as a lower monthly price, not as a “your credit” line. Confirm with your tax preparer.

Heads up: proposals are designed so you look at one figure: “25-year savings.” That number blends assumptions you do not control (rate increases) with costs that are in the contract (escalator, payment, lender fee) and omits what is inconvenient (minimum charge, degradation, inverter replacement in year 12). Ignore that figure until you have found the other seven numbers. If you cannot find them, it is not a proposal: it is a sales pitch formatted as a table.

Quick red flags

• No monthly production, only annual.
• The usage they used does not match your bills.
• Price per watt is absent and the salesperson does not know it.
• “25-year warranty” without saying on what.
• Projected bill of $0.
• 30% credit on a 2026 purchase.
• Sign on the tablet today, PDF “later.”

When NOT to sign

• When any of the seven numbers is missing and the salesperson cannot add it in writing.
• When the proposed monthly payment (plus the minimum charge) equals or exceeds your current energy line.
• When the design sits below 100% of your usage “to fit the budget” without telling you that you will keep paying grid kWh at full rate.
• When the system is bigger than your roof can hold per the site survey and the proposal did not change.

What to check before you decide

• Ask for the monthly production table and compare it against your 12 bills.
• Calculate cash and financed price per watt and compare against the market ranges.
• Find the escalator clause and request the year-by-year payment table.
• Confirm the four warranties separately, with term and responsible party.
• Verify the projection includes the minimum charge, ~0.5% annual degradation and no tax credit that no longer applies.