Elon Musk unveiled prototypes of Tesla's solar roof tiles in October 2016. They came in four styles that looked just like normal roofing material but were essentially miniaturized versions of traditional solar panels. The roof tiled reveal helped Tesla justify a 2.6 billion dollars acquisition of solar city and represented Musk's vision for where the businesses could do together. It's been almost two years since then so where are the tiles?

We now have several hundred homes with solar roof on them, and that's going well. It takes a while to just confirm that Solar Roof is going to last for thirty years, and all the details work out - said Elon Musk.

As it may this year, Reuters reported that they're actually only 12 tiled roofs connected to the grid, all in Northern California. Tesla declined to give an updated figure, but later clarified that hundreds of homes refers to roofs that are scheduled for install or are only partially installed.

Tesla has been accepting thousand-dollar deposits for the roof tiles since May 2017, but at that point the company wasn't even close to mass producing them. It established a factory in Buffalo New York to make the tiles, but it's not running at full capacity yet, and in the company's most recent annual shareholder meeting, Musk blamed ongoing delays on a need for more testing:

There's only so much accelerated life testing that you do on a roof, so before we can deploy it to a large number of houses, we need to make sure that all elements of the roof are going to last for at least three decades. Ideally sort of half a century or more.

Solar Tiles like large solar panels use silicon solar cells to convert sunlight into electricity, but it turns out this tech is difficult to shrink and to manufacture.

It's a little bit like saying the early iPhone screens, which were real breakthroughs, were just smaller versions of your flat screen on your wall. Making things small actually changes a lot of the way the technology will work, and that's been a big challenge, I think, for Tesla, but certainly for the whole industry overall to try and miniaturize it in a way that keeps it cost-effective and also gives it the very reliable performance Solar is known for - said Andrew Beebe.

One of the customers with the tiles already installed is San Jose resident and Tesla Model 3 owner, Tri Huynh. He pre-ordered as soon as possible, and the roof is installed earlier this year:

I was actually super surprised I got the call, just because you never know if this stuff right. I thought there'd be extreme delays. I just didn't know how long it’s going to take.

While traditional solar panels can be installed in a day, it took a team of 10 to 15 workers two weeks to install this roof. When asked him why his home was chosen:

They said it was kind of proximity to their headquarters, so that they could do quick troubleshooting. I think the simplicity of the house helps. You can see my house has a very simple roof layouts on it, like complicated roof, so I think that goes into account as well.

Tesla's customers are paying a premium for the tile suite look. Winds roofs cost him about $100,000, though he didn't need to replace his roof anyway:

I don't think it will ever pay itself, honestly.

For people that don't need a new roof, but want to install solar, traditional panels are definitely cheaper.

People have often said to me: “do we need to find some great new technology to finally make solar work?” and I think the answer is no. The solar industry has one in America. We have made solar cost effective in most of the country - said Andrew Beebe.

But Huynh is excited to be an early adopter and see his energy bill decrease:

Traditionally in the summer, my power bill is around $400 $450 in the summer. My last bill was only $40.00.

Ultimately, Tesla's goal is to make the tiles a cost-effective option. Partly by ensuring they're more durable than other rooftops. Tesla's promising 30 years of solar power generation.

“I would expect these solar roofing tiles, in just a few years, to be quite reasonably priced, if they can get the market interest that they're hoping for” said Dan Kammen.

Experts anticipate a wave of new solar installations within the next three to five years:

Not just for homes, for businesses, for new mini malls, for all kinds of built infrastructure where we can make solar the go-to product. It's not just a roofing shingle anymore, it's a power plant on your roof - said Dan Kammen.

Tesla says solar roof installations will scale up later this year and into 2019:

It's highly likely that great engineers and incredible technologists and a lot of those people might be at Tesla are going to be able to take this very difficult challenge, and engineer the heck out of it and get us to that cost parity we're not there yet - said Andrew Beebe.