How to Read a Solar Proposal Without Getting Lost

You requested a solar quote, and now you are staring at a 15-page PDF full of charts, projected savings graphs, financing tables, and equipment specs. It looks impressive. It is also designed to overwhelm you into trusting the salesperson instead of reading the details.

Solar proposals are not complicated once you know what to focus on. Most of the document is filler. There are exactly six numbers that determine whether a deal is good, bad, or somewhere in between. Here is how to find them.

The Six Numbers That Actually Matter

1. System Size (kW)

This is the total capacity of the solar panels being installed, measured in kilowatts (kW). A typical residential system in 2026 is between 6kW and 12kW.

What to check: The system size should match your electricity usage. A good rule of thumb is that 1kW of solar produces about 1,200–1,600 kWh per year depending on your location and roof orientation. If your annual electricity usage is 10,000 kWh, you need roughly a 7–8kW system to offset most of it.

Red flag: If the proposal recommends a system significantly larger than your usage, ask why. Some installers oversize systems to increase the sale price. You cannot always sell excess power back at favorable rates, especially in states that have moved away from full retail net metering.

2. Total Cost Before Incentives (Gross Cost)

This is the total price of the system before any tax credits, rebates, or incentives are applied. It includes equipment (panels, inverter, racking), labor, permitting, and any other fees.

What to check: In 2026, the average cost per watt for a residential system is $2.50–$3.50 per watt. An 8kW system should cost roughly $20,000–$28,000 before incentives. If you are quoted significantly more than $3.50/watt, you are likely overpaying unless you are getting premium equipment (like SunPower Maxeon panels) or have an unusually complex installation.

Red flag: Some proposals bury additional fees — roof work, electrical panel upgrades, extended warranties, monitoring subscriptions — in the fine print. Make sure the gross cost includes everything.

3. Net Cost After Incentives

This is what you actually pay after any applicable state tax credits, utility rebates, and other incentives. This is the real price of your system.

Important 2026 update: The federal 30% Investment Tax Credit (Section 25D) expired for homeowner-purchased systems on December 31, 2025. If a proposal shows a "Federal ITC" or "30% federal credit" as a line item deduction for a purchased system, that is incorrect. Some installers are still using proposal templates from 2025 that automatically include this credit. It does not apply to new purchased systems in 2026.

What to check: Verify that any incentives listed actually apply to your address and are currently active. The only valid credits are state tax credits, utility rebates, and local programs — not the federal ITC. If your state offers a solar credit (NY, MA, MD, SC, IL, CT, and others do), that should appear as a line item.

Red flag: A proposal that includes the expired federal 30% ITC as a deduction is either using outdated templates or is deliberately misleading you about your net cost. Ask the installer explicitly: "Does this include the federal ITC?" If yes, ask them to rerun the quote without it.

4. Estimated Annual Production (kWh)

This is how much electricity the system is projected to produce per year. It depends on system size, panel efficiency, roof angle, shading, and your geographic location.

What to check: The proposal should show the assumptions behind this number — specifically the solar irradiance data for your location and any shading analysis. Reputable installers use satellite imagery and software like Aurora or Helioscope to model production. Ask if they did a shade analysis or if the number is a generic estimate.

Red flag: If the estimated production seems high relative to the system size, the proposal may be using optimistic assumptions. Compare the production estimate to PVWatts (a free tool from the National Renewable Energy Laboratory) for your specific address and system size.

5. Payback Period

This is how many years until your cumulative savings from reduced electricity bills equal the net cost of the system. After this point, every dollar saved is profit.

What to check: A good payback period in 2026 is 5–10 years, depending on your state incentives and electricity rates. If the proposal shows a payback period under 5 years, verify the assumptions — it likely includes aggressive electricity rate escalation projections. If the payback period is over 12 years, the deal may not be strong enough to justify the investment.

Red flag: Pay attention to the electricity rate escalation assumption. Most proposals assume your utility rates will increase 3–5% per year. This has been historically accurate, but some proposals use 6–8% escalation to make the savings look dramatically better. Ask what rate they used and compare it to your utility's actual historical increases.

6. Monthly Payment (If Financing)

If you are financing the system through a solar loan or lease, the monthly payment is what you will actually pay each month.

What to check: Compare the monthly payment to your current electricity bill. In a well-designed system, your loan payment should be close to or less than your current bill. Also check: Is there a dealer fee built into the loan? Many solar loans include a 15–30% dealer fee that is rolled into the principal, meaning you are financing $30,000 for a system that costs $24,000.

Red flag: Dealer fees are the biggest hidden cost in solar financing. A 25% dealer fee on a $24,000 system means you are actually borrowing $30,000. This dramatically increases the total cost of the system and extends the payback period. Ask explicitly: "Is there a dealer fee in this loan?"

The Fine Print to Actually Read

Equipment Specifications

Check which panels and inverter are included. In 2026, you want panels with at least 20% efficiency and a 25-year production warranty. For inverters, Enphase microinverters and SolarEdge optimizers are the market leaders. Avoid proposals that list "panels TBD" or generic equipment descriptions.

Warranty Coverage

A standard solar warranty in 2026 includes: 25-year panel production warranty, 12–25 year inverter warranty, and 10–25 year workmanship warranty from the installer. If any of these are shorter, ask why.

What Happens if You Sell the Home

The proposal should explain the process for transferring the system (and any financing) if you sell. Owned systems transfer with the home and add value. Leases require the buyer to assume the lease or you to buy it out — this can complicate a sale.

Key Takeaways

• Focus on six numbers: system size, gross cost, net cost, annual production, payback period, and monthly payment
• Cost per watt should be $2.50–$3.50 in 2026 — anything above $3.50 needs justification
• Always ask about dealer fees in solar loans — they can add 15–30% to the total cost
• Verify production estimates using PVWatts (free NREL tool) for your specific address
• Check the electricity rate escalation assumption — 3–4% is realistic, 6%+ is aggressive
• Get at least three proposals before making a decision

Related articles:

• What Nobody Tells You About Solar Quotes
• Solar Lease vs Buy vs PPA: Which One Is Actually Better
• The 5 Red Flags in a Solar Sales Pitch

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