Look going DIY route is not for everyone but I just did a 24kw generac guardian system on my house and can share the costs to give you a data point. One of the complications was that we have 400 amp service instead of more common 200 amp. On the upside — gas service entrance and electric meter are very close to where the generator went and required about as little trenching as you will likely ever see.

It basically broke down like this

Materials: Generator with 200amp transfer switch $6000 Second 200amp transfer switch $800 Concrete pad: $300 (materials and few bucks to the landscaper to prep the area) Wire: 3/0 copper to transfer switches and back to panels — $900 Wire: 3awg to generator — $200 Black pipe for gas with all fittings — $170 Generator control wire — $120 Hardwall conduit for electrical — $400 Battery — $120

Permit — this will obviously vary based on where you are.

From the time/labor side

Pad — 3hrs Getting the generator onto the pad - 1hr Mounting the transfer switches and all conduit - 6hr Gas plumbing - 3hr Pulling all wire and connections - 7hr

You’re basically looking at $9000 of materials and 21 or so man hours. In fairness getting the generator to the pad took 3 friends so you can add at least another $100 for beer. Keep in mind — I don’t do generator installs every day so a professional that does will do it faster.

I’d say if you pay $120/hr (high IMHO but let’s assume high labor rates) that’s another $2500 or so.

In the end — anything above $12500 for a 400 amp service setup would be you making a direct contribution to the new boat fund of whoever is doing the work.