Elon Musk. I’ve long thought his greatest contribution would be to captivate and fascinate humanity with his wild and innovative STEM based ideas — and thereby inspire a whole new generation of STEM professionals. I really do think that will be an important part of his legacy. What I want to talk about in this post is a shadow side of his flashy 2016 solar shingle product announcement.

I want to start by re-setting the record here (for those unaware) – the solar shingle is NOT a new product.

Dow and CertainTeed both brought solar shingle products to the market YEARS before Musk’s heralding. Dow did it in 2009. Its a great idea – arrays “lay in” the roof, and not above it. They are far less intrusive on the sight-lines of homes. Lets face it, traditional solar systems can look just plain ugly.

Those shingle systems had the following disadvantages relative to standard systems:

1. They used thin-film technology rather than crystalline silicon (cSi), and required special attention to stringing.
2. An array would have FAR more “modules” and therefore a statistically larger opportunity to exhibit a failure.
3. The material cost for the modules and inversion (for a similar generation capacity) was higher.
4. They were less efficient, which means traditional systems generated more energy per square foot of array. Reasons?

– All solar modules, cSi and thin-film produce less power with increased operating temperature. Shingles sit flush with no air gap between the shingle and the roof surface. This implies more rapid heating and higher operating temperatures than standard modules. [1][2]

– Thin-film cells tend to be less efficient by their very nature.


Fast forward to 2016.

Elon Musk makes waves announcing the Tesla Solar Shingle! Having already captivated much of humanity with his flashy car company (those Tesla’s are beautiful, aren’t they?), space plans, and tech-rockstar lifestyle, his announcement is delivered with great impact. America listened. Without context.

I can’t tell you how many folks that I’ve worked with who have been touched by the Musk effect, and wanted to discuss solar shingle options (and battery options, but thats another story entirely).

So very exciting! And yet… so already been done.

The very same advantages and disadvantages of the early CertainTeed and Dow products are still at play (however I would expect material pricing premium to be minimized – a prospect of what I would imagine to be highly automated manufacturing process at the Buffalo NY gigafactory).

What’s more… ambiguous or no information was delivered on these key aspects:

  1. Efficiency – we could only guess. [2]
  2. Price – not a clue.
  3. Technicals – very little provided.
  4. Availability – what to expect here? Another case of overambition?

Regarding Efficiency….

Musk briefly touched on this in the product release when he mentioned that the glass material shielding the solar cell results in a very minimal efficiency drop for the photovoltaic shingle. But in an industry where a new record for PV efficiency is announced almost every month and the cost of solar is directly tied to how well a solar panel produces electricity, the real numbers on what this glass shingle can achieve will be crucial.

Regarding Technicals…

Standard solar panel technologies are typically evaluated based on their performance, durability, and warranties. However, there are relatively few technical details available for Tesla’s solar roof shingles. Tesla has not revealed how efficiently the panels will generate power, what kind of warranty the company will offer, or how they will be installed.

So where are all the installations?

To date (9/2018), there are only a handful, and it appears this is primarily due to production problems at the Buffalo gigafactory. Reality has been raining on the big guy’s ambition parade as of late… Anyways, see here for news on a real installation.

What about the cost?

Musk announced publicly that the pricing would be $21.85 per square foot. Ok sports fans, this couldn’t be more ambiguous to the average consumer. In order to understand the shingle cost for a job, you would need to start with a desired production, work backward through to the array(s) size (the number of modules based on unpublished efficiency), find the total surface area of the array(s) and multiply by his figure. Forget it. Instead, lets frame his figure relative to this figure — for a traditional tier-1 cSi module (which would have superior efficiency and hence require less square footage of array): $10.37. The Tesla product is therefore approximately TWICE as expensive as traditional technologies on a per area basis (I can’t derive a per-watt figure because I don’t have dimension and efficiency information). Consumer Reports also covered the higher cost here.

While the owner of our 3,000 sq. ft. home in California would typically install an 8.5 kW solar panel system for $26,030 before rebates, Tesla’s roof calculator shows that only a 6.25 kW solar roof priced at $50,900 is possible. The result is that Tesla’s solar roof will cost nearly $25,000 more than installing solar panels, and yet will only deliver 77 percent as much solar electricity (due to it being a smaller system size). You’re paying more for less, and that just doesn’t make good financial sense.

So… they don’t make sense?

No. Not right now. This article does a great job explaining scenarios where the Tesla shingle makes sense. Even if you fall into the category of having plenty of money and just want Tesla solar shingle because you just absolutely need to have them, good luck getting them.


Yeah, but Musk… the great captivator. At the end of the day his solar shingle announcement in 2016 actually created an impediment to traditional players in the solar industry. We had to administer a dose of reality to each Musk-enamored customer. Some “got it.” Some decided to WAIT for Musk’s magical new product. Regardless, 2+ years have passed, and wide-scale production and installation does not seem imminent. Your guess is as good as mine as to when they are coming, and when they do, surely they will be a SolarCity-only offer.


Oh, let us not forget that the 30% Solar Federal Tax Credit begins to sunset at the end of 2019. I predict the mixture of decreasing FTC coupled with relatively high costs and big delays will SEVERELY CRIPPLE Tesla’s plans for its solar shingle.


Others Are Seeing Through This As Well

[1] Note: Thin-film modules tend to outperform cSi modules when it comes to efficiency vs operating temperature. However, I expect flush mounting to create far higher operating cell temperature. This is basically confirmed by looking at the CertainTeed cut sheet for the ApolloII product. The NOCT (Nominal Operating Cell Temperature) for the flush mount shingles is 55.6C, as opposed to the typical 45C of a standard cSi module.
[2] Other installers have the same concerns regarding flush mounting of the Tesla product and its affect on efficiency.

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