Tesla
Elon Musk with a solar shingle option.
Musk first unveiled Tesla's solar roof product in late October, just a few weeks before the company acquired SolarCity in a deal worth $2.1 billion. At the time, Musk said Tesla's four different roof shingles will allow owners to ditch clunky solar panels in favor of an aesthetically appealing roof.
Better yet, Musk said it's likely the solar roof will cost less than a normal roof, factoring in the price of labor.
"It's looking quite promising that a solar roof will actually cost less than a normal roof before you even take the value of electricity into account," Musk said at the time.
Tesla is on track to begin selling and installing its solar roof later this year.
But Werner said he thinks it's unlikely Tesla's solar roof will be affordable.
"I'm frankly a little skeptical, but I've learned in 14 years not to discount entirely," Werner told Business Insider.
Tesla
Werner said he's skeptical because 10 years ago, SunPower offered a solar roof option, but found it was too expensive for the amount of energy it produced.
"You take the same material and you have less energy production because it's a little shingle," Werner said. "And then also, because they're part of the roof, they get hot. So you have to pay to keep them cool."
"It's a trade-off of looks cool versus costs more," he continued. "We found our customers said it doesn't look cool enough to offset."
SunPower isn't the only company that has had difficulty making the solar roof a reality. Dow Chemical Company discontinued its solar shingle business in July 2016 because they were less efficient, making them difficult to sell, Greentech Media reported at the time.
"It's a well-traveled path... this is not novel at all," Werner said.
In fairness, Musk is known to pull off what is thought to be impossible. After all, this is the same CEO behind a company that has landed a rocket on a floating platform in the middle of the ocean. He also has managed to keep his electric car business afloat during a time where many startups in the space went bankrupt.
It's also worth taking Werner's comments with a grain of salt. Sunpower, one of the biggest solar companies, was born out of Stanford University. But the company is now owned by Total, Europe's third-largest oil company.
However, it seems unlikely Tesla would offer a product that's exactly the same as its failed predecessors.
"What the form factor looks like could be novel, and I'm sure they'll come up with something novel," Werner said. "But the concept, lots of companies have been there."
Tesla declined to comment on Werner's claims.
We'll have to wait to hear more about Tesla's solar roof when it comes to efficiency and price. But Werner said if Tesla is successful, SunPower will be sure to resurrect a new-and-improved version of its solar roof to get a slice of the pie.
Werner added that even though Tesla creates competition for SunPower, Musk's entry into the space can only be a good thing for the solar industry.
"As a market leader with the best technology, the more he tweets, great," he said.