The problem is wasted potential. Why stop at some arbitrary capacity that may very well change with time? Better to cover the entire roof with solar panels. Use as much as needed and sell the excess energy. Why should people have to deal with energy storage? Let the power companies worry about that. The power grid can act as a backup.

The utilities foresaw this and didn't make net metering available to me. I presume my business model threatens the utilities somehow. They invented a kWh credit system to "pay" people with, and these credits expire every year if unused. Under these conditions, it'd be stupid to produce excess energy since I'd get nothing for it. Even if I were to somehow match production with consumption, I'd still have to pay them for the infrastructure.