[PNW Fireguy]

They don't provide a wiring diagram or as built because no two are guaranteed to be the same first of all and secondly it's a cost that makes no sense for Keystone to absorb.

I used to be an electrical superintendent for a commercial mobile factory assembled structure company many years ago. These are not wired by licensed electricians. The cost to the company and the subsequent sale price would be through the roof. The wiring is done by "trainers" ($30 +application in my state) a single electrician may review all the work on the production line then an inspector signs off and down the aisle it goes.

The best thing about the solar pre-wire marketing gimmick is that they provide you with a pathway and pull wire. Use the undersized wire to pull larger. You can use the undersized wire if you are installing your panels in series, but that's another discussion entirely.