A decent amount of your electricity bill is related to supply. Modern countries have a lot of rules around the reliability of their energy supply so companies spend a lot of money to guarantee that infrastructure is up to scratch. You're not paying for just the energy but for the transport of that energy.
A home system that uses its own electricity has the advantage of reducing the demand on the grid. A commercial system doesn't.
A home system that uses its own electricity has the advantage of reducing the demand on the grid. A commercial system doesn't.