Solar Panel Yield
It really makes no sense to make the panels the wall but you could mount something like the Solar Flower at intervals along the fence and not only get better yields but you’d have something that could protect itself from weather or even vandals if designed correctly. Under the proper conditions it would deploy from a hardened case and follow the sun taking an unusually low yield for panels on the wall to a vastly higher yield for panels and it looks really cool.
But why limit this to solar, Wind turbines would likely be more interesting in many places where the fence would run and while they can be bird blenders in the past new designs are developing that are relatively bird safe and also potentially more attractive.
Power
Now you are generating power what do you do with it? As noted the cost of transmitting the power can be relatively high and the technologies I’m talking about would generate far more than the security systems and drones would consume.
But you could put manufacturing plants near the wall that wanted cheap power, cities could grow up near the wall that supported these plants and also got clean power, and where the wall intersected rivers you could put in solar powered facilities that would clean out the pollutants and you could have solar powered pumping stations that moved that clean water along the wall enabling farming in places where it currently doesn’t exist. Finally, you could incorporate both personal and shipping transportation, automated and solar powered, so the goods that were created and the people that created them could move from the low-cost factories to homes and ports quickly and with solar powered efficiency. Likely an optimal use of Musk’s Hyperloop. So that you’d get a jobs bump not only when the wall was built but long after the wall was in place. This could justify a far higher spend up front and get the wall built faster.
