Self-driving electric cars? Rad!! A Hyperloop train that can get you from New York to L.A. in a few hours? No way! A space program that could one day fly missions to Mars and send tourists into orbit? Holy shit! A new kind of roof tile? Uh, sure. OK.

Aside from his drilling company that is literally called The Boring Company, Elon Musk’s newest endeavor to better mankind with solar energy-collecting roof tiles seems kind of dull. But it might be his most practical and affordable invention, depending on where you live.

What makes the Tesla Solar Roof a good investment is not just that it shaves a few dollars off of your monthly power bill, but that the tiles are practically indestructible — meaning the roof will last a lifetime.

The cost of a Tesla Solar Roof ultimately depends on how much energy you need and the percentage of active solar tiles on the roof itself. To help people determine that, Tesla also dropped a solar roof calculator with the release of the price this past summer, so people can estimate the exact cost and how much money the roof will save them in the long haul.

Determining the cost of a solar roof takes into account how much of the roof can be active solar tile and how much will just be the non-active glass tiles. A glass tile, without the solar elements, costs $11 per square foot, and the solar tiles themselves are $42 per square foot. For most houses, Tesla says only about 40 percent of the roof will be active solar, but the percentage of active tiles depends on how much energy a household needs.

So, if you live in a city with cheap installation, good tax credit, and lots of sun (sorry, UK), the Tesla Solar Roof might be the last roof you’ll have over your head.

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If you liked this video, you’ll probably want to watch this one, too: “SolarWindow Technology in Action”