Inside “Steel Pulse,” The Project That Became Elon Musk’s Solar Roof

Tesla’s sleek new product helped clinch the company’s merger with SolarCity. We investigate its mysterious origin.

Inside “Steel Pulse,” The Project That Became Elon Musk’s Solar Roof
[Photo: courtesy of Tesla]

In late August 2016, Elon Musk went to check out the first iteration of his new “solar roof” product on a customer’s home. Musk has famously high product standards, but he needed this one in particular to be a stunner. The Tesla CEO was in the middle of pushing through a controversial, multi-billion-dollar acquisition of SolarCity, the company his cousins Lyndon and Peter Rive cofounded. This new offering would be key to selling Tesla and SolarCity shareholders on the merger. In fact, just weeks earlier, on an August 9 SolarCity earnings call, Musk hinted that a “beautiful” roof product would soon be unveiled, telling analysts that it would create a “huge market” for the combined companies. “What if we can offer you a roof that looks way better than a normal roof? That lasts far longer than a normal roof?” he teased. “Different ballgame.”


Yet internally at SolarCity, the solar roof product was far from what he would consider market-ready, let alone beautiful, according to nearly a dozen sources familiar with the project. In recent months, SolarCity had focused on developing a standing-seam metal roof with solar integration, code-named “Steel Pulse.” Whereas traditional solar panels are usually mounted on top of existing shingles, the basic goal of Steel Pulse was to make the roof itself solar powered, so it looked like a normal roof, yet generated electricity through embedded solar cells. Some employees felt Steel Pulse was unattractive, but the project’s leaders, including then-CTO Peter Rive, seemed keen on its aesthetics, and pushed ahead. The company found customers who were open to having the latest prototype installed on their Bay Area home, and when it was ready, Peter invited his cousin to see the metal solar roof in the wild.

Musk hated the implementation. According to two sources, after he arrived, he told Peter and other team members that they were wasting his time with this “piece of shit.” He demanded more “stunning” concepts and soon directed the team to pivot their focus toward a different style of solar roof—and fast. After all, Tesla and SolarCity shareholders would be voting soon on whether or not to approve the merger. Musk needed this new product to live up to the expectations he had set on the earnings call weeks ago.

This story of the Solar Roof’s beginnings, gleaned through research conducted for Fast Company‘s new feature on the Tesla-SolarCity merger, sheds light on Musk’s approach to innovation. He has always thrived on the perception that he will be able to pull off the impossible, which affords him time to deliver on his promises and an unusual degree of goodwill when that delivery takes longer than expected. Given his successes at Tesla and SpaceX, why bet against him? But in this particular instance, considering the timeline of Steel Pulse’s development with the SolarCity acquisition, some insiders have wondered if Musk sold shareholders on a product that didn’t exist. “It’s all about the narrative for Elon,” says a source close to Musk. “Solar Roof was as ‘real’ as anything he’s ever shown [off to the public]. Was it a finished product? By no means.”

Related: The Real Story Behind Elon Musk’s $2.6 Billion Acquisition Of SolarCity And What It Means For Tesla’s Future–Not To Mention The Planet’s

The demo Musk introduced last October at a splashy presentation was a glass-tile solar roof, much different from the metal prototype he’d seen before. How did he pull off this transformation in just weeks? More to the point, who executed the idea and when? Leaders at Tesla and SolarCity, including Lyndon and Peter Rive, gave a variety of different answers on the timeline of its origin and development. At first, the companies said Solar Roof was a Tesla product, and then, later, a SolarCity product. Public statements are similarly contradictory. Some involved with the product’s development suggest that the mixed messages are a result of the combined companies’ wish not to appear as if they rushed out the glass-tile prototype in order to be able announce a high-profile product before the shareholder vote on the acquisition, which some critics viewed as Tesla bailing out SolarCity.


Solar Roof tile vs. hail at 110 mph

A post shared by Tesla (@teslamotors) on

The reality is that much of the early credit goes to an entrepreneur named Jack West and his R&D team, according to multiple sources. West cofounded a company called Zep Solar, which developed an attractive, industry-leading panel-mounting system. After SolarCity acquired the startup in late 2013, the mounting system helped lower SolarCity’s average time of rooftop solar installations from days to just hours.

The Zep Solar team operated relatively independently, with a culture unique from SolarCity’s. West and another cofounder, Daniel Flanigan, held impromptu jam sessions at their office in San Rafael, CA, and often code-named their products after musicians, such as “Jimi Hendrix.” The name “Steel Pulse” comes from the British reggae band.

Related: Can Elon Musk Get SolarCity’s Gigafactory Back On Track?

In late 2015, West and the Zep Solar team, which functioned as one of SolarCity’s R&D units, started more seriously exploring whether they could build an “integrated roof,” meaning that the solar cells would be built inside the roof itself. Such a vision would require that SolarCity begin handling complete re-roofing jobs, rather than simply installing solar panels. When West and team brought the idea to SolarCity execs, they stressed the advantages that SolarCity, with all its resources, would have going head-to-head with traditional construction companies and independent roofers, boasting in meetings that they would “kick their asses.”


Musk and Peter Rive were eventually sold on the idea, and SolarCity set about exploring a number of potential implementations. Though Peter and West considered a tiled concept early on too, they prioritized the development of a standing-seam metal solar roof—that is, Steel Pulse—and put together test concepts in San Rafael in the spring and early summer of 2016. “It was like a monolith, this ugly metal roof,” says someone familiar with Steel Pulse. A former SolarCity executive adds that some employees even “loathed” it. But there were cogent reasons to move ahead: It was inexpensive and brought efficiency advantages in terms of estimated solar conversion and installation times.

Slate-tile Solar Roof [Photo: courtesy of Tesla]
Musk, who had seen early concepts, apparently wasn’t as disdainful of the aesthetics at the time, because he hopped on that August 9 SolarCity earnings call to talk up its potential. Only weeks later, when he saw it on the customer’s roof, did he tell Peter Rive and Jack West that the Steel Pulse prototype was “a piece of shit” and push the team toward developing a better-looking version. (A spokesperson for Tesla clarifies that Musk “very much liked the idea of Steel Pulse. He simply did not like the first iteration.”) “He would say, this has to be insanely beautiful—that it had to knock your fucking socks off,” says a source.

Somehow, over the next few months, teams at SolarCity, Tesla, and 3M (which makes solar films that can be used for solar glass tiles) managed to put together a glass-tile solar roof demo, which Musk unveiled on October 28 at an event at Universal Studios’ back lot in Los Angeles, on an old residential set used in Desperate Housewives. Shortly before sunset, Musk appeared onstage in front of a crowd of several hundred to make his big reveal. “The houses you see around you are all solar houses. Did you notice?” he said, gesturing toward the homes with a grin. They appeared to have regular shingled rooftops, but Musk said they’d actually been retrofitted with a new product called the Solar Roof, a potentially transformative system that’s nearly indistinguishable from a traditional rooftop—and one, he promised, that lasts longer and costs less, all while generating electricity. “Why would you buy anything else?” he said. The crowd cheered.

The Tesla Model 3, Powerwall 2, and smooth-glass Solar Roof tiles [Photo: courtesy of Tesla]
Some people aware of Steel Pulse’s development at SolarCity were shocked by what Musk revealed. “Where the hell did that come from?” says one source, describing a common sentiment among certain teams at the time. Considering how different it looked from the standing-seam metal roof prototype, many sources concluded the demo was simply not real–it was merely vaporware. (As one jokes, “There’s a reason that they announced the idea on a fake block in a fake neighborhood with fake houses!”) A well-connected source explains, “Basically, from August to October, it was more about getting the thing to look right, and then from October until now, it’s really about getting the thing to work. This is just how Tesla does things. Their first car demo [for the Model S] was held together by magnets.”

A spokesperson for Tesla and SolarCity explains that the companies had been pursuing both a metal and a glass version for much of 2016, and that “Steel Pulse was a potential version of Solar Roof.” The spokesperson adds that some of the work that had been done on the metal Steel Pulse concept was transferable to the glass version, and that the current prototype of Solar Roof includes metal components.


Still, the company does acknowledge that the demos Musk unveiled at Universal Studios were not functional. Nor, as it happens, had Musk changed his view of the metal Steel Pulse version, which team members had installed on one of the houses there, according to sources. When Musk saw it, recalls one person familiar with the matter, paraphrasing, Musk said, What part of I fucking hate this product don’t you understand? The teams removed the prototype before the event, effectively killing Steel Pulse. (The company says that Musk was shown “five concepts of Solar Roof [at Universal Studios] and he chose his favorite four—all of them tiles.”)

No matter how the Solar Roof came to be, it seems to have worked: Three weeks after Musk’s presentation, 85% of shareholders approved the Tesla-SolarCity merger.

About the author

Austin Carr writes about design and technology for Fast Company magazine.