The construction cost alone would prevent this from happening on existing infastructure. You would have dc voltage drop between the panels and the long linear run to the inverters. You have service clearances for all of this equipment. The middle of the road either has existing underground drainage or is sloped down for drainage away from the roads so the slope is not flat fkr equipment. The trees on the side of the road would likely cause shading limiting the production. The power off the inverters are usually output around 600v which require a transformer to step it up to a distribution voltage to go any reasonable distance to fight voltage drop. Then the existing overhead lines they connect into need to have the ability to carry the power back into substations and even a lot of those are at full capacity. That's why solar developers typically pick sites close to substations or transmission lines to inject a high power density in one location. So yeah this is a terrible idea lol.