If you've ever sat through a solar pitch, you've seen the way the numbers are arranged. There's a big monthly-savings figure. There's a "compared to your utility bill" chart sloping nicely upward. There's a payment that "is less than your current electric bill." The actual economics of the deal are almost never the headline.

Here are the five numbers I look at first, in the order I look at them. None of them require special software — you can do all five yourself in twenty minutes.

01 — Price per watt (PPW)

Take the total contract price and divide it by the system's DC size in watts. A 8.4 kW system at $28,000 is $3.33 per watt.

What's normal in Colorado right now is roughly $2.70 – $3.20/W for cash, and meaningfully higher for financed deals — sometimes $3.80 – $4.40/W once the dealer fee is included. If your quote is above the cash range and you're paying cash, something needs explaining. If it's above the financed range and you're financing, you're paying a premium even on top of the premium.

02 — The escalator

If you're on a lease or PPA, the contract probably has an annual escalator — a fixed percentage your payment increases every year. 2.9% is common. 3.9% is aggressive. Anything at 4% or above is a problem.

The pitch is that utility rates increase faster than the escalator, so you come out ahead. The honest math is that utility rates have historically averaged 2–3% per year nationally, and far less in some periods. An escalator that beats the utility's actual rate growth turns the lease into a loss.

03 — Loan APR and dealer fee, together

If your quote shows an APR that seems unbelievably low — 0.99%, 2.99%, sometimes 5.99% — there is almost certainly a dealer fee built into the cash price. This is the finance company's compensation for the below-market rate, and it's paid by inflating the cash price by 25–40%.

To find it, ask the installer: "What's the cash-equivalent price if I pay outright instead of financing?" The difference is the dealer fee. A 5.99% APR with a 30% dealer fee is significantly more expensive over the loan life than a 9.99% APR with no fee.

04 — Production estimate vs. PV Watts

The proposal will quote you an annual production estimate in kWh. Run your own number through NREL's PV Watts calculator (linked from the Tools page) using the same panel count, tilt, azimuth, and shading. If the proposal's number is more than ~5% above the PV Watts number, ask how that gap is being claimed.

Sometimes there's a legitimate reason — different panel-level modeling, optimized tilt math. Sometimes there isn't.

05 — Workmanship warranty terms

Most quotes will advertise a "25-year warranty." That's almost always referring to the panel manufacturer's product warranty, which doesn't help you if the installer drilled a leaky penetration into your roof.

The number worth checking is the workmanship warranty — the installer's promise to fix things they installed. Look for:

• Length of coverage (10 years is OK, 25 years is rare and meaningful)
• What it covers — roof penetrations, leaks, labor for service calls
• Whether it transfers if you sell the house
• What voids it (often: any third party touching the roof, including a roofer)

The order matters

Run PPW first. If it's far above market, the rest of the analysis is moot — you're overpaying and that's the headline. If PPW is reasonable, the escalator, dealer fee, production estimate, and warranty terms tell you whether the rest of the deal holds up.

None of this requires a paid review. If you do this checklist and something doesn't add up, that's when it can be worth having someone else read the documents with fresh eyes — but plenty of homeowners catch the big issues on their own. That's the point of the post.