Solar Quote Checklist: What a Home Solar Proposal Must Explain Before You Sign

A home solar proposal can look simple: panels, price, savings, signature. The details decide whether the system performs the way the quote promises. A strong solar quote does not only tell you what the system costs. It explains why that system fits your home, your electricity use and your budget.

This checklist covers what a proposal should show, what to question, and how to compare two offers fairly. For a deeper look at how panel performance affects production, see this guide to solar panel efficiency and panel selection.

1. System size should be based on your real energy use

A solar system should be sized around the household’s actual electricity use, not around a standard package. Two homes with the same square footage can use very different amounts of electricity depending on climate, appliances, insulation, EV charging and work-from-home habits.

The proposal should list 12 months of past usage in kilowatt-hours and show what share the system is expected to cover. Ask whether the design accounts for changes you expect soon:

• Electric vehicle charging
• A heat pump or new air conditioning
• A pool pump or hot tub
• A home office, a growing household or an addition
• A battery you may add later

If the quote is based only on last year’s bill and you plan to add a large load, the system may feel undersized in two years.

2. The roof layout and shading analysis should be visible

A good proposal includes a layout showing which roof planes hold panels and why. South-facing roof areas are often the best choice in the northern hemisphere, but east- and west-facing sections can still make sense depending on your utility rates and daily usage pattern.

Trees, chimneys, vents and neighboring buildings reduce production. The proposal should state how shading was measured, for example with an on-site survey or satellite modeling, and how the design reduces its effect. If shading is ignored in the quote, it will show up later in the production numbers.

3. Panels: the model, wattage and warranty

The proposal must name the panel manufacturer and model, not just “premium panels.” Then check:

• Rated wattage and module efficiency
• Product warranty length, and the performance warranty terms
• Expected annual degradation, usually listed on the datasheet
• Appearance, such as an all-black design
• Compatibility with the proposed inverter

The best panel is not always the most powerful one on paper. It is the panel that fits your roof, your budget and your long-term plans. You can compare current options in the solar panels for sale range.

4. Inverters: string, optimizers or microinverters

The inverter converts the direct current from the panels into the alternating current your home uses, and a central string inverter is the component most likely to need replacement during the system’s life.

When people search “microinverter vs string inverter,” the right answer depends on shading, roof complexity and budget. The proposal should explain why the installer chose a particular design and how monitoring works. See also the power inverters range for the equipment types available.

5. Savings estimates should show their assumptions

A savings number means little without the assumptions behind it. Look for:

• The electricity rate used today and the assumed annual increase
• The expected first-year production in kWh and annual degradation
• Whether incentives are included, which ones, and whether you qualify for them
• Net metering or export rules from your utility
• The system cost after incentives and the payback period

Be careful with a perfect-looking payback period. Incentives, utility rate structures and net metering rules change often and differ by state. The federal residential clean energy credit (Section 25D) is not available for systems placed in service after December 31, 2025, so a quote for a system you buy and install in 2026 should not count it. Ask the installer which state, local or utility incentives the quote assumes, and verify them with your tax professional and official sources such as the IRS residential clean energy credit page.

6. Financing should be easy to read

A low monthly payment can hide a high total cost. For a loan, check the interest rate, term, fees and what happens if you sell the house. For a lease or power purchase agreement, check the escalator, buyout terms and any lien or filing on the property. Our guide to buying versus leasing explains the trade-offs in detail.

7. The installation timeline should include more than install day

A realistic schedule includes the site survey, design, permitting, installation, inspection and utility permission to operate. Ask for a written estimate of each stage. A system that is installed but cannot be switched on until the utility approves it is still not producing savings.

8. Warranty coverage should be broken down

Solar warranties come from different parties, and a vague line like “25-year warranty” can mean several different things. The proposal should separate:

• Product (equipment) warranty for panels and inverters
• Performance warranty, typically the guaranteed output of the panels over time
• Workmanship warranty from the installer, covering roof penetrations and wiring
• Roof warranty protection if the installer drills into your roof

Find out who honors each warranty and what happens if the installer goes out of business. Our article on solar panel warranties covers the common traps.

9. Battery storage should be discussed honestly

A battery can provide backup power and help you use more of your own solar energy, but it adds cost. A proposal that offers one should say which loads it will back up, for how long, and how it behaves during an outage. Standard grid-tied systems usually shut down during a blackout for safety reasons, so backup power usually requires a compatible (hybrid or backup-capable) inverter and a battery. See our guide to solar batteries for the main battery types.

A better solar proposal checklist

1. Twelve months of your actual electricity use
2. System size in kW and expected annual production in kWh
3. Panel and inverter make and model
4. Roof layout, orientation and shading assumptions
5. Total cost, cost per watt and incentives assumed
6. Financing terms, including total cost over the life of the loan or contract
7. Separate warranty terms and who honors them
8. Permitting, installation and utility approval timeline
9. Monitoring details and what happens if production drops
10. Battery and backup details, if included

Final thoughts

Compare at least two or three proposals on the same basis. If a number looks too good, ask for the assumption behind it. A trustworthy installer will welcome the questions.

Frequently Asked Questions