Designers have long dreamt of layering solar panels onto car roofs.
In theory, it sounds like a win-win - it's not like you're doing anything else with the space, and it could help power EVs.
While there have been plenty of long-distance races completed by cars with solar elements like this, precious few are road-legal, and the list of actual car manufacturers allowing this sort of option for real customers is vanishingly thin - with Tesla one of the many who don't.
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Elon Musk talked about the idea back in 2017, but concluded it wasn't cost-effective at that point.
The idea is obvious - the roof of your car is in the sun or natural light all day (unless it's in a garage) so could be gathering solar energy as you drive to extend your car's range - it's literally free energy.
In an attempt to see whether this system could work on a real, drivable ,commuter-friendly car, YouTuber DartSolar took things into his own hands.
His 20-minute video shows how he went from having the idea to actually building a folding-out array of nine solar panels to go on top of their Tesla Model Y.
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It's a fascinating process, involving more than a little engineering and fabrication. This means it's not exactly a guide if you want to try it yourself, and the results are really interesting.
We can't pretend they look great when folded out, of course - the panels are squared off, and basically just sit on top of the car like a big plank of wood.
Still, DartSolar's calculations and experiments suggest that, on a sunny day, he could gain anywhere from 20 to 75 miles of extra range for his Tesla, accounting for different conditions.
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That means that people could potentially run their whole commute to and from work without ever using energy from the grid - an exciting prospect for anyone keen on renewable energy.
Of course, how well this kind of thing works would totally depend on where you live - someone living in California will likely get a lot more charge than anyone driving round in Scotland.
It looks a bit rudimentary at the moment, but we can only hope this sparks a bit of inspiration - and engineers will start thinking about how to make this dream a reality for the rest of us.