When he unveiled Tesla and SolarCity's upcoming product in October, a solar roof that generates electricity but looks pretty much like a regular roof, Tesla CEO Elon Musk said the roof would cost less than a regular roof — if you count in the savings from the roof's energy generation.

While that's perfectly OK for those thinking long-term, if the solar roof's upfront cost were much bigger than the cost of a regular roof, that would probably deter some customers from going solar.

Now, however, Musk claims the solar roof will cost less to manufacture and install than a non-solar roof, even without the electricity savings.

Musk said so on Thursday, Bloomberg reports, after Tesla shareholders approved the company's acquisition of SolarCity.

“So the basic proposition will be: Would you like a roof that looks better than a normal roof, lasts twice as long, costs less and—by the way—generates electricity? Why would you get anything else," Musk said.

Why, indeed. If Tesla can deliver on this promise — to sell a solar roof that costs less than a traditional roof, with electricity generation being just a bonus, it would be tough to convince a customer not to buy one.

But how can this be possible? While the actual solar roof tiles won't be cheap, Musk anticipates big savings on shipping — the solar roof tiles being more durable and lighter than traditional ones, they would be significantly cheaper to ship.

There's still no price for Tesla's solar roof, either standalone or in the (likely) package with a Tesla PowerWall 2 home battery and an electric car charger. The product is scheduled to hit the market in 2017; if the company delivers on this promise, the future of solar energy for homeowners is looking bright.