Key reasons quotes aren’t the same
Several concrete factors cause wide swings in quotes. The roof: pitch, age, material and how much shading you have affect system size and labor. System sizing and production: companies may recommend different system sizes or use different production estimates (kWh per year) for the same array. Equipment: panel wattage, efficiency, brand and inverter type matter. Labor and installation methods: mounting style, roof reinforcement and permitting time add costs. Financing and contract structure: cash purchase, loan, lease or power purchase agreement will change upfront costs and long-term pricing. Local rules and utility interconnection can add fees or delays. Finally, installer overhead and local market pricing vary—larger companies and national installers like Sunrun or Sunnova may price differently than local crews. All of these combine so two quotes on the same house can look quite different.
What to compare line-by-line
To make quotes comparable, line them up on a few key items: - System size (kW) and expected annual production (kWh). Don’t compare price per watt without checking the production estimate. - Equipment list: panel model and wattage, inverter model and number, and any monitoring hardware. - Warranties and what they cover: product, performance (degradation), and workmanship. - Installation details: roof penetrations, mounting method, and whether roof fixes are included. - Permitting and interconnection fees, and who handles them. - Financing and contract type, including any long-term service obligations. - Estimated timeline for installation and activation. Ask each installer to explain assumptions behind the production estimate and to show their key line items in writing.
Tradeoffs to consider
Lower price may mean lower-grade panels, a smaller system, or a simpler warranty. A higher price could include premium panels, a better inverter, or more thorough roof work. Some companies build a buffer into production estimates for shading or future degradation, which reduces the expected payback but is more conservative. Leasing or PPA offers lower upfront costs for some homeowners, but they change who owns the system and how maintenance and incentives are handled. Installer quality matters: a cheap installation could lead to problems that cost more later. Balance equipment quality, installer reputation, and contract terms rather than choosing the lowest sticker price alone.
Questions to ask before you sign
Before you commit, get clear answers in writing: - Exactly how many kWh per year is the system expected to produce, and what assumptions were used? - Which panel and inverter models will be installed, and what are the manufacturer warranties? - Who is responsible for permitting, inspections and interconnection? - What happens if your roof needs repairs mid-project? - Are there any recurring fees, monitoring charges, or performance guarantees? - If you finance, what are the loan or contract terms and how do they affect long-term costs? If a company won’t put key details on paper or answer technical questions, consider getting another quote from a different installer.