What’s the True Cost of a Tesla Solar Roof?


The answer isn't as simple as it sounds

Tesla first announced they were making a solar roof late last year. At the time, Elon Musk teased that a solar roof would cost the same as or even less than a normal roof. But without providing details, it was anyone’s guess what it would actually cost.

That was last year. Now, Tesla has released actual numbers, so we can get a better idea of how much one of these roofs will really cost. There’s a lot of information contained in Tesla’s post, so let’s break it down a little.

What makes up a Solar Roof?

Tesla’s solar roof is made up of two types of roofing tile — a standard roofing tile and the solar tiles. These two tiles look identical from ground level but are very different. You can see the cost breakdown of the two tiles below. I’ll get to the negative cost in a minute.

The non-solar tile is a fairly standard roofing tile. Initial reports show it coming in at $11 a square foot. This actually places it cheaper than competitors, and only more expensive than asphalt shingles. The tiles are made of tempered glass, making them extremely durable. And they come with a lifetime warranty — or as Elon is fond of saying, an infinity warranty.

Now, back to those negative cost solar tiles.

Obviously, Tesla isn’t paying you to take these off their hands. What they’ve done is shown the cost of the tiles, minus the value of the electricity they’ll generate. The upfront cost of the solar tiles is expected to be $42 a square foot. These tiles come with a 30-year power and weatherization warranty, and a lifetime warranty on the glass.

What will a roof actually cost?

In short, it depends. That’s because the cost will vary depending on how many solar vs. non-solar tiles are installed.

Tesla used the Consumer Reports estimate that a Solar Roof would need to cost less than $24.50 per square foot for a 3000-square-foot roof to compete with a traditional roof. Tesla claims that its roof beats this at $21.85 per square foot — significantly less than the cost of a traditional roof.

But there’s more to this number than meets the eye. The fine print says:

“The price was calculated for a roof where 35 percent of the tiles are solar (solar tiles cost more per square foot than non-solar tiles), in order to generate $53,500 worth of electricity, which according to Consumer Reports would make a solar roof more affordable than an asphalt shingle roof.”

So, the actual cost vs. savings could be quite different depending on the mix of tiles and cost of electricity, and how much electricity is actually generated. This estimate includes no solar incentives, which could make the system more affordable. But if your system generates less electricity than expected, or if electricity from the grid is relatively cheap in your area, the Solar Roof might not pencil out for you.

Finally, Tesla also factors in the cost of a Powerwall 2 battery storage pack. This new battery pack doubles the storage capacity of the original, bringing it up to 14 kWh — enough to power an average 2-bedroom home for almost a full day.

Who stands to save with a Solar Roof?

You may or may not save money depending on what type of roof a Solar Roof is replacing.

To get the most savings, you could simply install a cheap asphalt shingle roof (where material costs can come to under $1 per square foot, not including installation) with a traditional solar array. Or you can keep whatever roof you have, if it’s in good shape and not too old, and install regular solar panels on that. Either of these options will cost much less upfront and still deliver the cost savings from solar.

After the initial upfront costs, it’s possible that with the Tesla Solar Roof you might save a small amount compared to a traditional asphalt shingle roof with solar, over the lifetime of the roof. But again, that depends on many things like the size of the roof, the amount of solar tiles you use, and the cost of electricity in your area.

But if you have a tile roof that you’re replacing, a Solar Roof could save you big. It may cost more upfront, but the savings over the lifetime of the roof could come to tens of thousands of dollars.

Chances are, people in the market for the Tesla Solar Roof will be those who care enough about aesthetics not to want an asphalt shingle roof in the first place — and those whose first consideration may not be the cost. Perhaps Tesla will do for solar tiles what it did for electric cars. That wouldn’t be a bad thing.

Integration as a key to success

With its acquisition of SolarCity, Tesla clearly sees integration as important to success. Tesla envisions one system that provides power and storage and is seamlessly controlled from your phone or computer.

Tesla’s not the only company that feels this way. It’s been argued that an integrated electricity market is coming, whether or not Tesla brings us there.

It may come with products like the SolPad, which features an inverter and battery storage right in the panel, and which is controlled from a smartphone app. Or like SolarWindow, which integrates solar cells into windows and feeds the power into a building’s electricity system. SolarWindow is in a trial mode now, but in the future, it could be an excellent option for skyscrapers.

A healthy dose of skepticism

The SolarRoof pricing numbers are very intriguing, and if Tesla can pull them off, they could make for a compelling product. That said, many in the industry are skeptical. Tesla isn’t the first company to offer solar shingles. Companies like Dow Chemical and NRG Home Solar have offered them in the past, but stopped due to higher cost and lower efficiency.

There’s also the issue of installation. Roofers aren’t electricians, and these systems are designed as a complete roof replacement.

Still, there was equal skepticism when Elon Musk said he was going to start an electric car company — and a rocket company, for that matter. But so far he’s two for two, and I’d be hard pressed to bet against him.