They shouldn't and they won't as it doesn't make economic sense in most cases, though, some of the large warehouse might generate more from their flat roofs than they need inside - factories, probably not, small business probably not. Though they just built and In-n-Out burger near my office that has a solar panel "shade" that feeds into the restaurant and also the car chargers in their parking lot. If you're going to do it, do it as best as you can and again surface area is the key to it all.
But if taxpayers are putting $10 billion into it via subsidies (like we have a choice lol), it makes more sense to install the panels as close to the demand as possible. That would help make up the 20% shortfall you are experiencing in terms of capacity vs usage if it were fed back into the grid.
Curious, do you have on-site battery storage as well?
But equally important is making my home more energy efficient: caulk sealing cracks, gaskets around doors, replace my old AC and natural gas furnace with a variable speed heat pump (with heat strips for the few days it's too cold for the heat pump), and replaced my natural gas water heater with a hybrid water heater (runs at only 300W with a built-in heat pump that I make even more efficient by ducting to its air intake warm air from the attic, and during the warm months I duct the cold air from the water heater into an air intake of my central HVAC so that the cold air the water heater creates helps cool the home).
IMHO all of the other stuff should be done whether or not one goes solar (except maybe getting rid of natural gas appliances altogether like I did since my natural gas isn't free but electricity is mostly free).