DETROIT >> Electric car maker Tesla has added another product to its lineup: Solar roof tiles.

As of today, customers worldwide could order a solar roof on Tesla’s website. Installations will begin next month in the U.S., starting with California. Installations outside the U.S. will begin next year, the company said.

The glass tiles were unveiled by Tesla last fall just before the company merged with solar panel maker SolarCity Corp. They’re designed to look like a traditional roof, with options that replicate slate or terracotta tiles. The solar tiles contain photovoltaic cells that are invisible from the street.

Tesla CEO Elon Musk said one of the drawbacks to home solar installations has been the solar panels themselves: They’re often awkward, shiny and ugly. Buyers will want Tesla’s roof, he said, because it looks as good or better than a normal roof.

“When you have this installed on your house, you’ll have the best roof in the neighborhood. The aesthetics are that good,” Musk said in a conference call with media.

The roof is guaranteed for the life of the home, which is longer than the 20-year lifespan for a typical, non-solar roof, Musk said. It has gone through the same hail, fire and wind testing that normal roofs endure.

Tesla’s website includes a calculator where potential buyers can estimate the cost of a solar roof based on the size of their home, the amount of sunlight their neighborhood receives and federal tax credits. They can also put down a refundable $1,000 deposit to reserve a place in line.

Tesla said the solar tiles cost $42 per square foot to install, making them far more costly than slate, which costs around $17 per square foot, or asphalt, which costs around $5. But homes would only need between 30 and 40 percent of their roof tiles to be solar; the rest would be Tesla’s cheaper non-solar tiles which would blend in with the solar ones.

It would cost $69,100 to install a solar roof with 40-percent solar tiles on a 2,600-square-foot roof in suburban Detroit, according to Tesla’s website. That includes a $7,000 Tesla Powerwall, a battery unit that stores the energy from the solar panels and powers the home. The roof would be eligible for a $15,500 federal tax credit and would generate an estimated $62,100 in electricity over 30 years. Over that time period, Tesla estimates, the homeowner would save $8,500.

Tesla said the typical homeowner can expect to pay $21.85 per square foot for a Tesla solar roof. The cost can be rolled into the homeowner’s mortgage payments and paid for over time, the company said.

Musk wouldn’t say how many orders the company expects to get this year. He expects the initial ramp-up to be slow.

“It will be very difficult and it will take a long time, and there will be some stumbles along the way. But it’s the only sensible vision of the future,” Musk said.

Palo Alto, California-based Tesla Inc. is making the solar tiles at its Fremont, California, factory initially. But eventually, all production will move to a joint Tesla and Panasonic Corp. factory in Buffalo, New York. Panasonic makes the photovoltaic cells used in the solar tiles.

Tesla said it will be installing equipment in the Buffalo factory over the next few months.

Tesla shares rose $3.96 to $325.22.