Every roof in a city, All bus shelters, car parks with shade roofs.
Ive often wondered why there's not solar snaking down the highways. There's so much unused land between roads just waiting for panels.
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.
Once base load and/or peaker plants become unprofitable, you either lose those or end up paying for them to idle.
Neither outcome is very desirable.
Energy storage is unlikely to come to the rescue in time.