Over the weekend, Tesla showed off its latest gadget: a solar trailer, featuring extendable panels, a satellite internet terminal and even a lick of matte-black paint.

Tesla may have designed the trailer to add some range to electric vehicles — or to advertise Starlink's new $25-per-month "portability" feature, which SpaceX announced in May. Whatever it's for, you probably won't see this trailer for sale any time soon.

That's because Tesla apparently exhibited it as a "show of concept," per a Tesla fan, who shared photos of the solar trailer on Twitter. The gadget was displayed at IdeenExpo, a tech conference geared toward high school-aged students in Hannover, Germany. Tesla did not respond to a request for comment when asked about the trailer. As such, there are lots of unknowns, including its size, weight and razón de vivir.

Anyway, solar cars have stood at the horizon for more than half a century, and it's likely they'll remain there for some time. Sure, concepts and limited-run vehicles grab headlines every so often, but solar cells tacked onto the roof of a sedan can only generate so much energy. For many folks, a range boost from solar simply wouldn't be worth the added cost.

Nevertheless, at least one company has promised to release solar kits for Teslas (it hasn't delivered them yet). Plus, the automaker itself said it would make a Cybertruck (which is not yet in production) with a retractable solar cover.

That's neat and all, but don't let it distract you from Tesla's track record on solar. The company made some splashy announcements (see: "Master Plan, Part Deux") around the time that it acquired SolarCity, but since then Tesla's solar marketshare has plummeted. We've seen reports of rooftop solar panel fires, ghosted customers and deployment delays, to boot.

So, maybe Tesla has the right idea with this solar trailer. Concepts are light and fun; being stuck without a roof? That's something else entirely.