Sounds like you’ve done the homework. Most of those solar arrays you see on rooftops around here do not directly power the house. It’s fed into the grid and the utility “pays” the owner for the power in the form of lower electric bills. Figuring the ROI on that is really tricky.
The only kind I would consider would be an arrangement like yours. Any electricity produced would go directly to our house.
L
Vermont power company no longer compensates you for what you contribute to the grid. Off the grid is the only way to go.