How to Read a Solar Quote: The Nine Lines That Matter

Key Takeaways

• A proposal's glossy production graph is the least informative page. The specification table and the price lines carry everything.
• Normalize every quote to price per watt on the cash price — the only way two proposals become comparable.
• Check the modeled production against PVWatts for your address. A proposal running well above it is making assumptions, not promises.
• Two lines decide more than the hardware: the cash price and which tariff you'll interconnect under.

The nine lines

1. System size, in kW DC. The headline number. Everything else normalizes against it.

2. Panel model and count. Note it, then stop worrying about it — reputable tier-one modules are broadly similar, and panel technology differences are smaller than marketing suggests. What matters is that the count times the wattage equals the system size you were quoted.

3. Inverter type and model. String inverter, microinverters, or optimizers. This is a real design decision — shading patterns and roof planes drive it — and worth asking why the installer chose theirs.

4. Modeled annual production, in kWh. The number all savings claims descend from. Run PVWatts yourself for your address, tilt and azimuth. Proposals running materially above a neutral model are where optimism enters the document.

5. The cash price. Ask for it explicitly and in writing. If financing is offered, the gap between this and the financed price is the dealer fee.

6. Price per watt. Cash price ÷ watts DC. This is the only figure that makes two quotes comparable, and most proposals don't print it. Do the division yourself.

7. Equipment warranties. Panel product and performance warranties, inverter term, battery terms if included. Long and largely uncontested across the industry — failure is genuinely rare.

8. Workmanship warranty. The one that actually protects you, because it covers roof penetrations and installation defects. Ten years is a common benchmark; shorter deserves a question.

9. Who handles permitting and interconnection. Should be the installer. This is the long pole in every project, and your net metering terms attach to that application.

Normalize first, then compare. Two proposals for the same roof can differ by a third on price per watt while looking similar on the summary page.

What the savings graph is doing

Every proposal ends with a twenty-five-year savings chart, and it is the most persuasive and least reliable page in the document. Three assumptions drive it:

Rate escalation — the compounding assumption that utility prices rise a few percent annually forever. It dominates the chart's shape. Ask what rate was used and re-run the numbers at zero.

Export value — whether surplus is credited at retail or a fraction of it. Increasingly the latter, and a graph assuming full retail in a supply-only or net-billing state is simply wrong.

Incentives applied — in 2026, check specifically that no proposal is still applying the expired federal residential credit. It's the single most common stale line in circulation this year, and it moves the chart by tens of percent.

The three questions that end the meeting

"What's the cash price for this exact system?" Everything downstream depends on it.

"What rate escalation is in this savings projection?" If the answer is 4%, ask to see it at 0%.

"What tariff will I interconnect under, and is it grandfathered?" The hardware on your roof will outlive several rate regimes. Which one you lock in at interconnection matters more over twenty-five years than any panel brand on page three.

A good installer answers all three without friction, because good installers know their proposals survive scrutiny. That's the real test of a quote — not what it claims, but how it behaves when you ask it questions.