Tesla is pushing back the timeline for its solar roof roll-out.

CEO Elon Musk tweeted in March that the company would begin taking orders for its four solar roof shingle options this month. But during a TED Talk Friday, Musk said that two of the tile options won't be available for purchase until early 2018.

"Yeah we are starting off with two initially and then the second two will be introduced early next year," he said.

A Tesla spokesperson declined to comment further on Musk's comments and why the roll-out strategy had changed. Customers will be able to order two of the four shingle options in a few weeks.

Tesla ultimately plans to sell four different tile styles: textured glass, smooth glass, French slate, and Tuscan glass. Musk did not say which options will go up for sale first.

Musk has said that the solar roof will be cheaper than a normal roof, even before factoring in the value of generating electricity, a vow he reiterated on Friday.

Tesla unveiled its solar roof product last October, a month before it acquired SolarCity in a deal worth $2.1 billion. The company will produce the solar cells for the shingles at its plant in Buffalo, New York.