What an online quote does and doesn't do
Online estimates are automated. You usually enter an address and utility bill details or connect your account, and the tool uses satellite imagery and weather data to estimate system size and expected production. That process is fast and useful as a starting point, but it can't inspect roof condition, confirm shading at different times of year, or check your electrical panel. Treat online quotes as ballpark estimates, not final offers.
What an installer quote adds
Installer quotes come from a site visit or detailed virtual assessment. A technician will check roof age and structure, look for hidden shading, inspect your attic and electrical panel, and measure for mounting constraints. They’ll include local permit and interconnection fees and note any required roof repairs or upgrades. Installers also select specific equipment and layouts, which changes cost and expected production. Large providers such as Sunrun or Tesla Energy Solar may offer both quick online estimates and full installer bids; comparing both versions helps you see which assumptions change.
Common changes between online and installer quotes
Typical adjustments include system size and layout (modules moved or reduced because of shading), different equipment choices (panel or inverter brand and model), added costs for roof repairs or flashing, updated labor or permit fees, and changes to estimated energy production once a precise orientation and shading study is done. Incentives or rebates might be applied differently after an installer verifies your eligibility. Remember that final pricing depends on location, roof, utility usage, financing, and installer quality.
How to compare quotes before you request bids
Ask for itemized estimates so you can compare the same things across bids: system size (kW), estimated annual production and assumptions, equipment brands and models, rack and inverter type, roof work or structural fees, permit and interconnection costs, and expected timeline. Check whether production estimates use conservative or optimistic sun-data. Request photos or a shading map from the installer. Look at reviews, ask for references, and confirm who handles paperwork with the utility. Comparing line items, not just the headline price, shows where tradeoffs are being made.