Where the money goes
A typical 20 kW project breaks down roughly like this: the generator and transfer switch ($5,000–$7,000), electrician labor and wiring ($2,500–$4,500), gas plumbing ($500–$2,000 depending on distance), pad and site prep ($300–$800), and permits/inspection ($100–$500). All-in, most homeowners land between $10,000 and $15,000 — the unit itself is only about half.
Propane adds a tank if you don't have one: an underground 500-gallon tank installed runs a few thousand dollars more. And if your panel needs a service upgrade, add $2,000–$4,000. Get three local quotes — installer pricing varies more than equipment pricing.
Haven't picked a size yet? Run the kW size calculator first, then read our installation cost guide for the full breakdown.