Solar quotes can look very different from one installer to the next. One proposal may list a low price but leave out important items, while another may include everything but look more expensive. Learning a few key terms helps you compare offers on equal footing and avoid surprises.
System Size in Kilowatts
System size is measured in kilowatts (kW) and is the combined rated output of all panels. A system of 6 kW, for example, could consist of fifteen 400-watt panels. A larger system produces more electricity, but the right size depends on your annual energy use, roof space, shading and goals.
Price per Watt
To compare quotes, divide the total price before incentives by the system size in watts. A 6 kW system priced at $18,000 works out to $3.00 per watt. This number lets you compare proposals of different sizes. A lower price per watt is not always better if equipment quality or warranty coverage differs.
Equipment Details
- Panels: Brand, model, wattage, efficiency and degradation rate.
- Inverters: String inverters, microinverters or power optimizers, which affect performance and monitoring.
- Racking and wiring: Mounting hardware that must suit your roof type.
- Batteries: If included, the capacity, power rating and backup capability.
Production Estimates
The quote should show estimated annual production in kilowatt-hours based on your roof's orientation, tilt and shading. Ask how the installer calculated the estimate and compare it with your annual consumption.
Warranties and Guarantees
Look for a product warranty on the panels and inverters, a performance warranty on panel output, and a workmanship warranty from the installer. Ask how long each lasts and who handles claims if the installer goes out of business.
What Is Included
- Permit and interconnection fees.
- Roof work, panel removal for reroofing and electrical panel upgrades.
- Monitoring system and customer support.
- Incentives or tax credits assumed in the price.
Cash, Loan or Lease
The financing method changes the total cost over time. For loans, check the interest rate and fees. For leases and power purchase agreements, examine the escalator, the term and what happens if you sell your home.
Get Multiple Quotes
Gather at least three proposals, verify licenses with the state contractors board, and read independent reviews. Ask for everything in writing, and take your time. Reputable installers will answer questions without pressure.
This article is general information. Incentives and rules change, so confirm current details with your installer and a tax professional.