Elon Musk might make grand statements, but he has a track record of backing them up with results. Like creating reusable spacecraft, for example. But Musk's latest sentiments about his SolarCity energy company might break that streak. "I don't want to commit 100 percent to this yet, but it's looking quite promising that a solar roof will actually cost less than a normal roof before you even take the value of the electricity into account," he said, on a recent investor's call. "So, the basic proposition would 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?' It's like, why would you get anything else?"