The regulatory overhead to grid-connect is a _significant_ portion of the price, both for the actual paperwork labor and because of the premium it imposes on the system components (you can't use inexpensive non-UL-listed panels)
Net metering hasn’t been allowed in my county in more than two years so that can’t be it.
Is this really a thing in the US? At least in Europe, rooftop solar like OP mentioned doesn't require grid-connection?