I thought this real technology was closed five days after opening (
https://www.scmp.com/news/china/society ... design-not , I've looked up for when it has been reopened but haven't found anything, I'm eager to know whether, when and for how long it reopened, you can PM me if you don't want me to derail this thread further).
You can hand wave a lot of things with magic materials, but you can't handwave poorer sun exposure than tilted panels, let alone sun tracking ones. You cannot handwave geometry away. This is independant of material ; I can take any magic panels you have in mind, orient them (and incidentally be unable to walk on them) and have a better yield (and we still have a lot of unused space on our roofs).
As far as factorio goes, solar paveways could be cool, solar rooftops would be cooler (more area to place them in a typical dense factory location, not unlike IRL with typical dense urban area). So let's do both, have a solar paveway that is buildable, and solar paveways below building representing rooftop panels (graphism can come later).
As far as their economics go, make them twice more ressource intensive (per energy produced) than regular solar panels, if anything, for gameplay experience : you don't want old solar panels to become completely useless, so solar rooftops/paveways should offer an expensive and space efficient alternative to regular solar panels, which seem to represent dedicated solar farms using tracking panels. They may be as or more energy dense though, both for a gameplay and from a realistic perspective.
I've chosen the number 2 purely for gameplay purposes, it can be anything that offers meaningful choice to the player. It happens to be realistic of static tilted rooftop solar panels vs sun tracking ones, but the absence of energy loss over long transmission distances makes it heavily biased toward dedicated solar stations as we have now (and rooftop performances makes paveways unrealistically appalling, even discarding fast deterioration and higher installation cost). In any case the precise balancing of the item should be motivated by gameplay (just like its very existence).