I have explanation, but you will not like it.
Parking lots have been built on cheap. Those who have roofs can’t support any added weight, while those who do not have roofs are far away from any serious electrical connection able to give the energy outside.
The whole idea can be done… on new parking lots.
Also - how about instead we build more water-plant power storage? They pump water to the upper reservoir using electricity in the middle of day, and then produce electricity from flowing water at dawn/dusk/night. This would up the demand for electricity when solar panels are overproducing it and push businesses to consider including solar panels in their constructions.





Okay, I give on the first part, but not on the second.
Farms consume quite a lot of electricity actually, and often electrical grid must be enforced more for a farm than for a suburbs.