What did the system cost? Rich people don't talk about amount payments, poor people do that. You are also assuming in 10 years, you will not be replacing it or have major repairs. How much of it was paid by tax payer? Could you have invested the money?
You are also not paying your share for up keep, and utilities are looking at base charges. You have the ability to use grid power. Some people get upset that they have to pay for that luxoury. But you pay for a truck whether you drive it or not. Your machine breaks down, you have a back up. Power line goes down, they are not allowed to put you at bottom of list of priority.
I suspect if more people go off grid they will increase or add charges. Don't like it get off grid completely.