Re: snaking down the highways—I'm not an electrician, but my understanding is that transporting electricity over distance is costly. First, because you have to

Re: snaking down the highways—I'm not an electrician, but my understanding is that transporting electricity over distance is costly. First, because you have to run and long-term maintain additional wire, which isn't free, but second because of something called "transmission and distribution losses"—essentially, some fraction of the power you generated gets lost whenever you send it along a wire. That's why the existing grid uses high voltage for transport and transformers to step it back down where it's going to be used. Solar panels are getting better and better all the time, but for a long time the marginal benefits of running them have been slim (once you offset the power generation by the cost to manufacture, install, and maintain them). And their output is notoriously unpredictable because it's dependent on weather. So, T&D losses alone are enough of a factor to make certain kinds of solar deployment unfeasible. Then consider how much easier maintenance would be if your panels are arranged in a conventional solar farm rather than running for miles down a highway. So, rather than snaking along highways, it's probably better to cluster all the panels close together just outside (or, as you also suggest, integrated into) a major population center.