Couple issues with that. One is how to get it to work and be approved by the utility. In many areas something like this is heavily regulated and you might not even be able to do it depending upon State law (assuming you’re in the States).
Another issue is that in many areas, unless you’re only offsetting the home or business, the excess isn’t profitable. Many utilities pay a fraction of what they charge for any excess put back on the grid.
That being said, I know some utilities are actually doing this. They’re renting roof space on large commercial and industrial buildings. It’s more profitable for them since they can get full market rate for the energy generated.