Even at 2-3 stories, I'm skeptical that there's enough roof surface area to provide enough solar panels to individually cover the electrical use of all the inhabitants. Many 2-3 story apartment buildings don't have parking lots at all - and it's a common pro-density urbanist political project to remove the requirements to build one, because it discourages car use and also makes projects cheaper - but even if they did, a small apartment also means less surface area for solar panels over the parking lot. And once you're in a building with multiple households, that means that the solar panels - and the amount of energy every individual household draws from them - has to be managed communally. I'm glad I don't have to justify the power use of my home server to a group of my neighbors concerned about managing a common resource, and just pay my power bill to the de-facto-monopoly state-regulated electric utility company.