Tesla roof calculator
…in which your blogger finds he has to take several deep breaths at the sheer vacuity and cluelessness of an anti-Tesla-solar-roof guy who tries to use a Net Present Value calculation to show that said solar roofing is not worth it. In essence, he’s saying, “I think it’s crap, ergo I’ll fudge something I don’t understand to show I’m right.”
Let’s see what the issue is. There’s an article on Inverse (not a site I’ve come across before) that discusses how much one of Tesla’s solar roofs would cost over time. Or, rather, how much you’d make from it after the initial outlay. Tesla has an online calculator to help you evaluate the costs and benefits. Here’s the screenshot from that article for 40% coverage on a 1800 sq ft house in California.
In other words, for an initial outlay of 59,100, you’d get a tax credit of 13,300, and you’d make 85,700 in energy (essentially, the savings from your power company) over 30 years.
Ah ha, says our doofus, quoting some site about Net Present Value (NPV) together with a mathematical expression to make him look like a Real Expert, natch, this means that if you ignored the tax credit, the NPV of the whole thing over 30 years comes to.11,788 when using a discount rate of 2%. NOT WORTH IT!
Adding in the tax credit back in? A measly profit of 1,512.
The calculations and results just made me go WTF? I pulled out my trusty calculator (it used to be the HP 12C, but nowadays I use an iOS calculator app): the first scenario gave me an NPV of 4,879, the second with the tax credit 18,179. Why the big differences?
When I was in the banking biz writing trading software for interest rate swaps and options, the one thing I learned about calculations that took into account the Time Value of Money (TVM) was: draw a diagram. Understand the cash flows over time by looking at a picture. Only then can you do some calculation like find the internal rate of return, find the NPV, or whatever. Our friend essentially drew this diagram for the no tax break scenario, at least in a virtual sense:
In other words, he imagines that at the end of the 30-year period (having received no payments in the interim in the form of energy savings) Elon Musk is going to appear at the end of his driveway, with a big goofy smile, camera flashes popping, holding a check for 85,700. If you imagine that’s the way it works, then sure, the PV of the lump sum at the end is 47,312, so adding in the outlay of 59,100 makes an NPV of.11,788. Yay! Except…
…that’s not what this savings calculation is all about. The calculator expressly states that the savings you get are over the 30-year period, not a lump sum at the end of 30 years. In other words, you would be receiving 85,700 / 30, or 2,857 at the end of every year:
The total PV of those 30 “receipts”? 63,979. So, if you subtract that initial outlay, you get an NPV of 4,879. Add in the tax break at the start and you get 18,179 as the overall NPV.
Of course, having said all that, we all pay our electricity bills monthly. So we should actually do these NPV calculations based on monthly savings over 360 months, at 238 per month. For that I get 5,306 NPV without the tax benefit, or 18,606 with it.
Of course, now we can play around. The cashflow diagram is like a mortgage: an initial outlay (for the bank) and then receiving monthly payments to settle it. The future value (FV) after 30 years is zero: the mortgager will have paid it all off. Let’s imagine that the initial outlay is a mortgage loan, and the loan is being paid monthly from the power savings, what is the interest rate? Without the tax advantage: 2.65% APR. (It’s at this point that the incoming savings, once present valued, equals the initial outlay.) With the tax advantage? 4.72% APR.
(If you have an HP 12C or equivalent: you specify four of N, i, PV, PMT, and FV, and the calculator will evaluate the fifth value. For the “pretend it’s a mortgage without the tax benefit” case, N is 360, PV is.59,100, PMT is 238, and FV is 0. The calculator makes the monthly interest rate 0.22%, which, when multiplied by 12 for the annual rate, makes 2.65% APR. For the tax benefit scenario, make the PV.45,800, then solve for i. I get 0.393% for the monthly interest rate, which is 4.72% APR.)
At the end of all that, what conclusions can I draw? With regard to the solar roof, well, if I had the house for which the Tesla calculator made this estimate, I’m afraid I don’t have 59,100 lying around to pay for the install and thereby reap the benefits. So I’d have to get an equity loan in all probability which would skew those NPVs I just calculated. Of course, such an improvement to the house (much as a remodeled kitchen or bathroom does) would increase the value of the house by some undetermined amount as well, offsetting the costs over time. In other words, if you want it, you’d possibly make the finances work and install it. If you don’t want it, this set of (corrected) calculations is not going to change your mind.
As for the article that raised my blood pressure in the first place (what’s up with that?), it’s from a climate-change denial site – no, I’m not linking to it – and it just makes me wonder about the accuracy of the other posts there. If this simple enough proposition cannot be argued correctly (this is friggin’ mathematics, people, as free from opinionated points of view as you can get), what hope does a reader have for accuracy for the remainder of the site? Or maybe the inaccuracies aren’t spotted because the posts reinforce a certain viewpoint? The article has at present over 200 Комментарии и мнения владельцев and not one commenter has seen the flaws. In fact, oh no, the author has made a comment showing that he doesn’t understand treasury bonds either and how they work and oh god I’ve got to stop reading this shit and instead mow the lawn and water the plants and do anything to stop this madness welling up inside my brain…
1 Response
#1 cherry morgan said.
Wow, this blog post was both informative and entertaining! I loved how the author took down the anti-Tesla-solar-roof guy who tried to use a Net Present Value calculation to show that solar roofing is not worth it. It’s frustrating when people try to use fancy math terms without actually understanding the underlying calculations. The author did a great job of breaking down the calculations and showing why the anti-solar-roof guy was completely off-base. I also appreciated the use of screenshots and examples to illustrate the calculations and results. This was a really engaging and educational post, thanks for sharing
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Tesla solar roof cost vs solar panels might surprise you.
Tesla unveiled their solar tiles in late 2016 and the big question on most of our minds remains the same: What is Tesla’s solar roof cost vs solar panels?
Originally Tesla was somewhat silent on the issue, but they’ve since published information on cost and added a calculator to their website that estimates both homeowners’ total cost to install solar tiles on their home as well as the savings they’ll earn over the life of the solar panels.
We at Understand Solar analyzed the cost data and took the solar calculator for a ride to see what we could find out.
Cost to Install Tesla’s Solar Tiles
First things first, let’s take a look the total cost to install these solar tiles, then calculate exactly how much you can save over the life of the roof.
Total Cost to Install
Tesla estimates that their solar tiles cost around 21.85 per square foot of roof space, with 35% of the roof tiles being solar tiles and the remaining being matching, non-solar tiles.
FYI, solar tiles can’t be installed on all areas of the roof, so Tesla is manufacturing matching tiles both with and without solar panels. The cheaper non-solar tiles are installed in shaded or north-facing areas of a roof where putting solar just doesn’t make sense. This allows you to only install solar where it’s beneficial, lowering your total cost and leading to more savings.
Strangely enough, the Tesla blog post linked to above actually pulls all its cost data from a November 2016 Consumer Reports article that estimated the cost of Tesla’s solar roof. Why Tesla cites a cost estimate from another company is beyond us. Tesla must have found the estimates so on point they decided to use them.
Perhaps a better cost estimate comes from Tesla’s own newly released cost calculator for their solar tiles.
With this calculator, you type in your address (presumably so Tesla can know the number of sunlight hours in your area as well as your utility rates), home square footage, and the number of stories in your home and it will calculate out general costs and savings.
Below is a quick rundown of installation costs for single story homes with varying square footage. To stay as close as possible to the cost estimate above, we chose to cover just 40% of roofs with solar tiles (there is no 35% option), though Tesla recommends 70% for max production. For the costs below, we’ve already included the 30% federal tax credit as well.
- 1,000 sqft home: 21,210 (21.21 per square foot)
- 2,000 sqft home: 40,250 (20.12 per square foot)
- 5,000 sqft home: 95,970 (19.19 per square foot)
Obviously, your home’s square footage doesn’t necessarily correlate to your roof’s square footage, but it gives a pretty good estimate if your home is a single story home. You can expect to pay around 20 per square foot – actually pretty close to the estimate above from 2016 (well done, Consumer Reports).
How does this cost compare to traditional roofing? Below we’ve highlighted the cost per square foot of a handful of common roofing materials. As you can see they are much cheaper than Tesla’s solar tiles, especially the ubiquitous asphalt shingle (all cost estimates from Homewyse):
- Asphalt shingle: 3.40 per square foot
- Metal Tile: 10.26 per square foot
- Clay Tile: 14.85 per square foot
- Slate Tile: 15.06 per square foot
Even slate tile – the most expensive traditional roofing material of the bunch – costs about 25% less than Tesla’s solar roof tiles. 40k for roofing? What gives? If Tesla’s solar tiles are so expensive, why are they such a big deal? Who can even afford them?
The not-so-secret secret, as you well know, is the fact that Tesla’s solar tiles are roofing as well as solar panels. After the installation, you’ll be producing your own electricity, allowing you to save money while the tiles just sit up on your roof.
This leads us to our next method of calculating Tesla’s solar tiles cost: looking at total savings.
Total Savings After 30 Years
This is where it gets good. As mentioned, the total installation cost is just one piece of the puzzle. Yes, Tesla’s solar tiles are expensive. However, over their lifetime they’ll be producing electricity that you can use directly in your home. Tesla’s Solar Roof is a financial investment. Yes, it’s a lot of money, but spending 10 today to get 15 tomorrow makes sense, right?
Let’s look back at our cost examples above for the different sized homes. Installation costs for Tesla’s solar tiles drop slightly as your roof gets bigger but generally fall around 20/square foot. Let’s see how much electricity each of these homes can generate. Tesla has yet to publish data on the efficiency or wattage of their solar tiles, so we’ll have to use their solar calculator again.
Obviously, the more sunlight hits a solar panel, the more electricity it will produce. This means that solar panels in different cities will produce different amounts of electricity. In their solar calculator, Tesla accounts for these differences as well as fluctuations between local utility prices.
Let’s compare a few very different cities to get an idea of how much electricity Tesla’s solar tiles can produce over 30 years (the claimed lifespan of the tiles), as well as the total net savings:
Los Angeles, CA
- 1,000 sqft home: produce 49,900 worth of electricity (net savings of 28,690)
- 2,000 sqfthome: produce 94,800 worth of electricity (net savings of 54,550)
- 5,000 sqft home: produce 180,600 worth of electricity (net savings of 84,630)
- 1,000 sqfthome: produce 42,800 worth of electricity (net savings of 21,590)
- 2,000 sqft home: produce 63,900 worth of electricity (net savings of 23,650)
- 5,000 sqft home: produce 127,600 worth of electricity (net savings of 31,630)
- 1,000 sqft home: produce 24,600 worth of electricity (net savings of 3,390)
- 2,000 sqft home: produce 46,800 worth of electricity (net savings of 6,550)
- 5,000 sqft home: produce 111,700 worth of electricity (net savings of 15,730)
You could probably have assumed this, but savings are highest in southern California, where solar irradiance (the strength of the sunlight) and utility rates are both sky-high. Even in North Carolina, though, Tesla estimates your total savings from solar will not only pay for your roof but also saves you thousands of dollars over the 30-year life of your solar roof.
Suddenly, Tesla’s solar tiles don’t look too expensive, do they?
Before you get too excited, a few caveats are in order:
- Tesla hasn’t released technical data (wattage, efficiency, etc) on their solar tiles, so we aren’t really able to verify these energy production claims.
- Obviously, a 5,000 square foot home is huge and probably wouldn’t be a single story home, so our savings estimate for that one is likely skewed. However, we kept all our examples as a single story home so we could compare apples-to-apples costs.
- Keep in mind that the calculator above doesn’t know your personal electricity use, so these savings amounts might be higher than what you can actually achieve. Without knowing more about the workings of the calculator, we’re left in the dark.
That being said, the calculator still performs one basic function well: it shows that a Tesla Solar Roof could be a good financial investment.
Tesla Solar Roof Cost vs Solar Panels
Here’s the big question: Tesla’s solar roof cost vs solar panels. When compared to conventional panels, do Tesla’s shingles still make sense?
Right off the bat, let’s say this: Tesla’s tiles are more expensive than normal solar panels. That makes sense as it’s really two products in one: roofing and solar.
Let’s dig into the numbers a bit: and compare costs for the average US home, which now clocks in at 2,700 square feet in size:
- Tesla Solar Shingles: At 21.85 per square foot, you’d shell out 58,995
- New Shingles Conventional Solar Panels: 9,180 for asphalt shingles and 11,970 for a 5.7kW solar installation (the average size in the US), for a total of 21,150.
As you can see, Tesla’s solar shingles really don’t make financial sense. Even if you install a giant solar installation – upwards of a whopping 10 to 12 kW – with conventional solar panels, you’re still better off financially. With Tesla’s solar shingles, you’re spending a lot more money for the same end result: a new roof and a solar installation that helps you save money.
Of course, things can and will change. will certainly decrease as more and more homeowners install Tesla’s solar tiles. Tesla’s already done it with their Powerwall 2, which packs quite a punch at a surprisingly low price.
Considering that you’re getting both solar panels and a very durable roof when you purchase Tesla’s solar tiles, it seems like they’re on course to be a game changer in the roofing industry and solar industry.
Who’s the Market for Tesla’s Solar Tiles?
At such a high cost, who’s the market for Tesla’s solar shingles? 40k for a 2,000 square foot home? That’s quite an investment. At such high cost, you’ve got yourself a niche product, at least until the price comes down a bit.
Obviously people buy cars that cost 30k to 40k, typically by taking out a loan. We’re sure the same thing will happen with these solar shingles as well. However, with the majority of the population having less than 1,000 in their bank account, a 40k investment in roof shingles is a longshot for most of the population.
Instead, just like Tesla’s incredible automobiles, the well-to-do are the likely early adopters of Tesla’s shingles. This isn’t such a bad thing though. The same thing happened with traditional solar panels as well: they were expensive at first and only a handful of wealthier homeowners could afford to install them. However, as more people jumped on the trend, panel production increased, dropped, and more and more people could go solar.
In fact, this was Elon Musk’s exact plan with their own electric vehicles: make a high-end product while the technology is expensive, then produce cars for the masses once the technology drops in price. This is a plan he adopted at the very outset of Tesla and made public back in 2006. Talk about vision!
So while at the beginning Tesla’s solar tiles might just be for the rich – even with the high savings over the life of the tiles – as time progresses and costs lower, they might just be the technology that shifts solar from a ‘green’ technology to standard technology – one you see (or more accurately, don’t see – that’s the point right?) everywhere.
Until then, the shocking height of Tesla’s solar roof cost vs solar panels will keep it out of reach of most homeowners. Better to just install ‘normal’ solar panels and enjoy that extra cash you’ll see.
Tesla Solar Roof: Everything You Need to Know
Elon Musk and the Tesla Solar program released the heavily-anticipated solar roof. The release of the solar roof also prompted a complete overhaul of the Tesla website; which you can now read up on information about the solar roof as well as place a 1,000 deposit to claim your solar roof.
Unfortunately, the unveiling of Tesla’s solar roof left us with a plethora of unanswered questions. Our preliminary findings were that the Tesla solar tiles were more expensive than expected and quite overpriced.
Besides the solar roof cost, however, there are still numerous other questions that need to be addressed:
- Solar Roof Cost vs. Solar Panels Cost
- How Does the Tesla Solar Roof Work with the Federal Solar Tax Credit?
- Solar Roof Efficiency vs. Solar Panel Efficiency
- How Much Do Tesla Solar Tile’s Weigh?
- Can the Tesla Solar Roof Work with a Flat Roof?
- Solar Roof Durability vs. Solar Panel Durability
- Who Should Buy a Solar Roof?
In our comprehensive analysis of the Tesla Solar Roof, we will give in-depth breakdowns of all the topics above. While Elon Musk and Tesla have been historically successful with product releases, the history of solar tile technology has not. This product is the biggest test for Tesla to date, and the fate of this new solar product is still up for debate.
Solar Roof Cost vs. Solar Panels Cost
When determining the value of the solar roof for you and your home, you need to take into consideration your roof size as well as your monthly electric bill amount. The higher your bill, the greater your electricity consumption, which in turn will mean you will require a greater number of solar tiles on your roof relative to non-solar tiles.
To help you understand the potential value of the solar roof Tesla created a calculator to show upfront estimates for their roof. The calculator is fun to play around with but it doesn’t take certain factors into consideration that would provide an actual comparison to the value of standard solar panels.
Tesla has said in the past that they “believe in transparency and putting the customer in control.” While this may be the case, it seems odd that the calculator doesn’t show you power ratings for the solar tiles. All it shows is total system cost and the ratio of non-solar tiles to solar tiles necessary to offset your monthly electric bill.
We will provide you with everything you need including required system size, all you need to do is register here.
Based off of your address we will show you:
- Usable sunlight hours per year
- Proper system size
- Yearly savings
- The increase in the value of your home
Equivalent trees planted from switching to solar Once you figure out the necessary system size for the Tesla Solar Roof you can then determine your Price Per Watt (PPW); this is a key number to have when comparing the cost of solar systems.
- Multiply your roof square footage by the percentage of the solar tiles
- Then multiply this number by 42 (the cost of a solar tile)
- Finally, divide by the number of watts
Using these calculations, the cost of the solar portion of Tesla’s Solar Roof comes out to 6.30/watt. With this number, there is a /- of about 0.50/watt since the Tesla solar calculator uses 10% increments.
These solar tile costs are approximately double the cost of some already available solar options. That leaves the big question of whether or not the aesthetics of a solar roof is worth an extra 25,000-35,000: a Tesla Solar Roof also requires an entire roof replacement.
So if you think the aesthetics of a solar roof is worth an extra 30,000 or so and you are ready for a roof replacement, you may want to consider visiting the Tesla website to put down your 1,000 deposit.
How Does the Tesla Solar Roof Work with the Federal Solar Tax Credit?
When it comes to the Federal Investment Tax Credit (ITC), Tesla claims it can be applied to their entire solar roof and their home storage battery the Powerwall. This is not necessarily the case. The issue here is that this type of solar technology doesn’t fit into the structure of the current ITC. For this to change, a special appeal process is necessary to decide which parts of the solar roof fall under the ITC.
This all depends on how the IRS decides to view Tesla’s new solar roof. If they determine the non-solar tiles are “so specifically engineered that it is in essence part of the machinery or equipment with which it functions,” then the entire roof will fall under the federal solar tax credit.
Determining the solar roof and its impact on the ITC will certainly be a lengthy process. As customer service advocates at Pick My Solar, we can only hope that Tesla will take care of the entire process for their homeowners.
The federal solar tax credit, however, is going to start scaling down at the beginning of 2020 and be completely phased out in 2022. When taking into consideration the buying and installation process of the newly released solar roof, a large number of homeowners may miss out on the chance to claim the federal solar tax credit.
“Taking pre-orders for this unproven technology will undeniably have a negative impact on the adoption of solar,” says Solar.com CEO Max Aram, “By leveraging Tesla’s sexy brand Elon Musk can lure a few thousand homeowners off the solar market. Many of these homeowners may never get their system turned on before the expiration of the Federal Tax Credit. The difference between Solar Roof and Model 3 is that Tesla has already proven they can manufacture great cars and Model 3 is coming at an affordable price point. With solar roofs, he hasn’t proven either.”
Solar Roof Efficiency vs. Solar Panel Efficiency
The brand new solar roof will be entirely manufactured in the United States. Tesla plans to manufacture all of their solar tiles at their Buffalo facilities using solar cells provided by their partner, Panasonic. Peter Rive, the CTO at SolarCity had previously claimed the efficiency of one of their solar tiles was equivalent to a standard panel. However, according to SolarCity’s website the colored film of the solar tile “allows the cells to blend into the roof while minimizing solar efficiency loss.” While it appears this would mean the efficiency of solar tiles would be lower than those of solar panel, this isn’t necessarily the case.
Currently, Panasonic’s N3300 HIT modules have an efficiency of 19.7%. The have developed solar cells as efficient as 23.5% in their labs. The solar industry average for solar panels is approximately 16%, while Pick My Solar’s installers come in at around 19.5%. So even if the colored film of the solar tiles lessens the efficiency by a few percentage points, the solar tiles efficiency still may be equivalent to that of standard solar modules.
When it comes to the efficiency of Tesla’s solar roof in comparison to standard solar panels, there is no clear cut winner. Just make sure that if your home is very limited in regards to roof space, you go with the highest efficiency module possible to power your home.
How Much Do Tesla Solar Tile’s Weigh?
Per Tesla, their new solar tiles will be approximately half the weight of a standard roof tile. This is a hard claim to make without defining the “standard roof tile” being used in this statement.
To understand the range of tile weights, let’s look at this:
- Concrete Tiles – between 9.5 – 12 lbs. per square foot
- Asphalt Shingles – between 2.5 – 4 lbs. per square foot
- Spanish Tiles – between 6 – 19 lbs. per square foot
- Slate Tiles – between 7-10 lbs. per square foot
Our approximation when taking all of the solar tiles components into consideration is that the tiles will weigh about 15 – 20 lbs. This is a rough estimate due to Tesla’s ambiguity when discussing the weight of their solar tiles.
We reached out to one of our excellent roofing partners, Chandler’s Roofing, to get their perspective on Tesla’s new solar product;
“Aesthetically the Solar Roof is beautiful, but we’ll need to wait and see how Tesla will resolve taking it to market,” says Trevor Leeds, President of Chandler’s Roofing, “Roofing is a different animal than solar. There are different variables that have to be considered like waterproofing and the roof-attachment method. Compliance codes for roofing are also much different than solar. Will Tesla figure out how to be a national roofing contractor? Is Tesla looking to assume this liability and overhead? All of these unknowns will need to be worked out.”
Can the Tesla Solar Roof Work with a Flat Roof?
Unfortunately for homeowners with flat roofs, the Tesla Solar Roof will not be an option for you and your home. The minimum roof pitch eligible for a solar roof installation is 3:12 (or 14 degrees). This puts the Tesla solar roof at a disadvantage considering solar panels can work on all roof types. All it takes for solar panels to be effective on flat roofs is a tilted racking system.
Solar aside, tiling is not recommended for flat roofs due to leaking potential. This is a very real risk considering the wiring components located inside the solar tiles.
Solar Roof Durability vs. Solar Panel Durability
Tesla is extremely confident in the durability of its solar roof. Elon Musk has stated that the Tesla Solar Roof has an “infinity warranty” or for the lifetime of your home, whichever comes first. While the durability of the new solar tiles has not been successfully field testing, there are videos online of the Tesla Solar team launching hail and other heavy objects at the solar tiles to show their durability. Based on a video recorded in a Tesla owned factory, it seems the solar tiles are stronger than a tempered-glass solar panel.
Standard solar panels, however, are usually warrantied by the manufacturer for 25 years and the panels typically will last longer than the warranty. The expected lifetime of solar panels has also been field tested, unlike the solar roof.
The biggest question here is what is going to happen when solar tiles start degrading and losing their efficiency? When solar panels need to be replaced or corrected (which is rare) it is a pretty simple replacement. But what happens when there are solar tile problems? How much of the roof is going to have to be replaced? It seems that making any corrections to a Tesla Solar Roof is going to be very expensive and labor-intensive.
Who Should Buy a Solar Roof?
The initial appeal of the Tesla Solar Roof will target the wealthy, tech-savvy homeowner with a passion for renewable energy. Due to the solar roof cost, the purchaser of a solar roof will have a deep passion for aesthetics.
There is certainly a risk-reward aspect of being one of the first owners of a Tesla Solar Roof. The reward is obviously being able to be one of the first owners of this beautiful technology. The risk is the same. Being the owner of the first version of anything comes with the risk of having to be patient while kinks are worked out.
If you want to be an owner of the Tesla Solar Roof you will need a large amount of expendable cash and an even larger amount of patience as it could take years for the solar roofs to get installed.
In Conclusion
There is no doubt that the new Tesla Solar Roof has brought excitement into the solar industry and with manufacturers recently going out of business, maybe the timing was perfect. With the buzz surrounding the new solar roof in full effect, even Elon Musk admitted the solar roof would have some tough challenges in the years ahead. So even with its beauty and PR buzz, we will have to wait and see what the future holds for Tesla’s solar roof.
For more Tesla and solar industry updates, please subscribe to our blog below.
Tesla Solar Roof: To Wait or Not To Wait?
The Tesla solar roof sounds like everything that our favorite 80’s era sci-fi novels and movies promised the future would bring. At Southern Energy Management, we’re just as excited about the Tesla solar roof as everyone else. And, as one of North Carolina’s select Certified Tesla Powerwall Installers, you can bet that we’ve got our eyes on all the latest news on Tesla solar shingles.
Quick Facts
One of the big questions, though, is “When will Tesla’s Solar Roof be available?” The short answer is that Tesla’s solar shingle product is still in the very early stages of launching on the East Coast.
Since Tesla’s solar shingle system is so new, especially in North Carolina, and because the pricing and energy savings for the roof are unclear, our stance is that if you’re interested in going solar in the next 5 years, your best option is going to be the tried-and-true panel technology that has been tested and continually improved since the 1970s. In the rest of this post, we’ll dive deeper into our reasons for that opinion so you can decide for yourself. But first, let’s make sure we’re on the same page about what the solar roof is.
What is the Tesla Solar Roof?
Tesla’s Solar Roof is made up of photovoltaic cells integrated into shingles. Tesla is not the first company to launch a solar shingle – we installed some of Dow’s now discontinued solar shingles in 2014 – but they’re definitely the sexiest attempt to date. Solar shingles function in the same way as traditional solar panels: photovoltaic cells convert photons from the sun’s rays into electricity.
A solar roof consists of both active and passive shingles. The active shingles do the actual work of producing energy for your home. The passive shingles are used on areas of your roof that aren’t suitable for the active cells – either because of building regulations or lack of solar potential – to maintain a uniform appearance.
Previously, there was talk of 4 solar shingle styles: Tuscan, Slate, Textured, and Smooth Glass. As of now, Tesla is only advertising a shingle that appears most like the Textured Glass option.
Tesla Solar Shingle Specs
Tesla’s solar shingles are a sleek, slate grey at 15”x45” and come with a 25 year tile, power, and weatherization warranty. The tiles have an ASTM D3161 Class F wind rating, and a ANSI FM 4473 Class 3 hail rating. That’s all fancy jargon to say the tiles are tested to hold up to 110mph winds and 1 ¾ inch hail.
When will the Tesla solar roof arrive in North Carolina?
A few installers have started to offer Tesla’s solar roof in North Carolina. Right now, NC homeowners who are getting solar shingles installed are paying a price premium to be in the front of the line.
As a Certified Tesla Powerwall Installer, we’ve talked with Tesla about the solar roof and previewed the product. At this point, we’re continuing to offer Tesla’s traditional PV panels, but not their shingle roof material. We love the Poweralls, solar panels, and solutions Tesla continues to put out, but since their solar roof product is still so new, with such complex technology behind it, we don’t want our customers to be first in line to experience the kinks of a first generation product. We know the Tesla solar roof is going to be a game changer and we’ll be on board as soon as we feel that this product has proven long term success for our customers.
If getting Tesla’s solar roof is make or break for you on your solar journey, we have good news — there are other solar companies in NC that have taken on rolling out this product! Tesla is also currently taking 100 refundable deposits to hold your place in line through their online ordering portal. That being said, there is no guarantee for when your solar roof will be installed (or by which contracted installer).
Powerwall Rebate
Each Powerwall installed between now and October 31, 2023 is eligible for a 500 rebate from Tesla. We’re also offering an extra 1,000 discount when you install a Powerwall with your solar system.
Solar Roof vs Solar Panels
There are two major differences between a solar roof and a traditional solar panel system — complexity and price.
Talk with any roofer or solar company that has worked with the solar shingle product, we’ll bet they’ll tell you that the Tesla solar roof is one of the most complex and intricate roofing systems that they have ever seen. An average 8kw solar roof will have around 460 solar shingles, which means there are 460 wiring connection points on your roof (or 460 possible break points). On the other hand, a traditional solar system for this size will include around 25 solar panels, meaning 25 connections.
With a traditional solar system, you can also get panel level solar monitoring so you would know exactly when a panel is underperforming while being able to pinpoint exactly where the problem is in your system. This level of monitoring just isn’t available yet for the solar roof, making it a challenge to quickly address any issues when they come up.
Next on the list is price. Tesla’s Solar Roof website has a slick calculator that takes your address and uses Google’s Project Sunroof to automatically generate a Solar Roof solution for your home. While the tool is fun to play with, the and energy savings it estimates don’t impress us when compared to traditional solar panels. Let’s take a deeper dive into price differences between the Tesla Solar roof and traditional solar panels.
What We Still Don’t Know About Tesla’s Solar Roof
The team at Pick My Solar tackle unanswered questions about the highly anticipated and still mysterious solar roof.
On May 10, Tesla announced it has begun taking orders for the company’s highly anticipated Solar Roof systems. The Tesla website now provides more details about the cost and durability of the tiles and allows interested homeowners to place a 1,000 deposit for the system.
For those who understand solar, however, the announcement of the new solar roof has prompted more questions than answers. On Pick My Solar’s blog, we briefly discussed the economics of Tesla’s solar tiles and found them to be significantly overpriced. A number of questions have subsequently been raised that Tesla has left ambiguous or unanswered:
- How can we accurately compare the cost of the Solar Roof to standard solar panel systems?
- How will Solar Roofs work with the federal Investment Tax Credit?
- What’s the efficiency of the Solar Roof tiles? How does this compare to conventional solar panels?
- How much do the tiles weigh?
- What about flat roofs?
- How does the durability of the solar tiles compare to conventional solar panels?
- Who should get a Solar Roof?
In this comprehensive review, we’ll investigate each of these important questions to reveal what’s known and still unknown about this new solar product. The Tesla Solar Roof follows a long line of largely unsuccessful building-integrated photovoltaic (BIPV) products. Despite all the excitement it has generated, the jury is still out on whether or not this product will meet a similar fate.
How can we accurately compare the cost of the Solar Roof to standard solar panel systems?
The cost and lifetime value of the Solar Roof depends on the size of your roof and electricity bill. A higher utility bill means greater electricity consumption, which means you will need more solar-generating tiles compared to non-solar tiles. Generally, the higher your utility bill, the more attractive the economics of the Solar Roof become.
Tesla has stated that it “believe[s] in transparency and putting the customer in control.” As such, the company created a Solar Roof Calculator to show upfront estimates for the system. It’s a fun tool, but it does lack certain key pieces of information that would enable a consumer to accurately compare the system cost to a standard solar PV system.
The calculator will display the total system cost and percent blend of solar tiles to non-solar tiles, but it doesn’t show you the power rating of the system. An easy workaround for this is to input the home address in Pick My Solar’s solar calculator, which will provide upfront the needed system size for a given location and bill amount.
Once you know the system production size in kilowatts for the Solar Roof, you can determine the key metric for comparing solar system costs: price per watt. Multiply the roof square footage by the percentage of solar tiles, multiply by 42 per square foot (what Tesla has disclosed as the solar tile cost), then divide the amount by the number of watts. With this methodology, we’ve determined that the solar-only portion of the Solar Roof costs 6.30 per watt, give or take 0.50 per watt because the solar coverage slider on the Tesla calculator only moves in 10 percent increments.
A cost of 6.30 per watt is essentially double some of the solar available today, and translates to a 25,000-35,000 premium on standard solar panel systems for the solar-only aspect of Solar Roofs. Is that premium worth it for superior aesthetics? Do you need a new roof, and are you in the market for something high-end? If you answered yes to both of those questions, you may want to consider putting down 1,000.
How will Solar Roofs work with the federal Investment Tax Credit?
On the Solar Roof calculator, Tesla says that the 30 percent federal Investment Tax Credit (ITC) applies to both the entire roof and the Powerwall energy storage product. But this isn’t as clear-cut as the Tesla website would lead you to believe.
BIPV doesn’t fit into the mold of the ITC structure and would need a special appeal process in order to determine which components of the system apply for the credit on a case-by-case basis. For example, solar shingles will qualify for the ITC, while the non-solar ones may not. This will depend on whether the IRS determines that the non-solar components of the Solar Roof are “so specifically engineered that it is in essence part of the machinery or equipment with which it functions.”
It will likely be a lengthy process for the IRS to clarify the ITC code. Hopefully Tesla will take care of this entire process for homeowners or educate them completely on the process of claiming the tax credit. Time is short, however.- this incentive is phasing down beginning in January 2020 and concludes in 2022. Considering the long timeline Tesla will need to fully scale Solar Roof production, many homeowners may not even be able to benefit from the entire credit.
Despite what’s shown on Tesla’s calculator, customers shouldn’t expect the full ITC benefits. The delay to receive a Solar Roof is likely to be even longer for customers outside of California. In the meantime, potential Solar Roof customers won’t be buying solar products that are already on the market today.
“Taking preorders for this unproven technology will undeniably have a negative impact on the adoption of solar,” said Pick My Solar CEO Max Aram. “By leveraging Tesla’s sexy brand, Elon Musk can lure a few thousand homeowners off the solar market. Many of these homeowners may never get their system turned on before the expiration of the federal tax credit.
The difference between the Solar Roof and the Model 3 is that Tesla has already proven they can manufacture great cars and that the Model 3 is coming at an affordable price point, he added. With solar roofs, [the company] hasn’t proven either.
What’s the efficiency of the Solar Roof tiles, and how does this compare to conventional solar panels?
Tesla plans to manufacture the entire product in Buffalo, New York, with cells made from its partner, Panasonic. Peter Rive, former CTO at SolarCity and now head of solar tech at Tesla, said the efficiency of the solar tile is equivalent to a standard solar module.
However, SolarCity’s website breaks down the anatomy of the solar tiles, including how the colored louver film “allows the cells to blend into the roof while minimizing solar efficiency loss.” This implies that some efficiency is sacrificed for the system’s aesthetics.
To date, Panasonic’s most efficient solar cells in production are the N330 HIT modules, which have an efficiency of 19.7 percent. The highest efficiency cells they’ve developed in lab are 23.5 percent. The market average efficiency of solar modules is around 16 percent, while the average for modules installers use on the Pick My Solar marketplace is around 19.5 percent.
Assuming that the colored louver film only reduces efficiency buy a few percentage points and that Tesla would be including the highest efficiency Panasonic technology in the tiles, that would validate Peter Rive’s claim that the solar tiles have more or less equal efficiency to standard PV panels.
At the end of the day, efficiency is not a deal breaker unless a home has limited roof space, in which case high-efficiency standard modules would be the better option. For homes with constrained roof space, it’s helpful to compare efficiency in terms of kilowatt per square foot. We’ve determined that Tesla Solar Roofs produce about 6 watts per square foot, whereas a high-efficiency module would produce 19 watts per square foot.
Simply put, if you do not have a lot of roof space in an area with the appropriate conditions for solar, a high-efficiency module system is a much better option.
How much do the tiles weigh?
According to Tesla, Solar Roof tiles are half the weight of a standard tile. However, the company has never defined what tile material it considers to be “standard.” Concrete tiles weigh between 9.5 and 12 pounds per square foot, while asphalt shingles only weigh 2.5 to 4 pounds per square foot. Spanish tile can weigh up to 19 pounds per square foot, but lightweight versions are only 6 pounds. Slate tiles weigh between 7 and 10 pounds per square foot.
We would guess that, when factoring in all of the solar tile electronic components, the tiles will weigh between 15 and 20 pounds per square foot, but it’s hard to say considering how vague Tesla has been in its statements.
It’s unclear whether more supporting components will be needed in the sheathing of the roof to support the solar tiles. If so, that would significantly drive up the net cost of the system. Regardless, it seems clear that installing the shingles will be an extremely complicated process.
“Aesthetically, the Solar Roof is beautiful, but we’ll need to wait and see how Tesla will resolve taking it to market,” said Trevor Leeds, president of Chandler’s Roofing, one of Pick My Solar’s roofing partners. “Roofing is a different animal than solar. There are different variables that have to be considered like waterproofing and the roof-attachment method. Compliance codes for roofing are also much different than those for solar. Will Tesla figure out how to be a national roofing contractor? Is Tesla looking to assume this liability and overhead? All of these unknowns will need to be worked out.”
What about flat roofs?
In sales training seminars, Tesla revealed that homes with flat roofs are not eligible for the Solar Roof. Solar Roofs can only be installed on roofs with a pitch of 3:12 (14 degrees) and more. This is a clear disadvantage versus standard solar systems, which can utilize a tilted racking system for flat surfaces.
Tiled roofing in general isn’t typically recommended for flat roofs due to waterproofing constraints, which is an understandably greater risk considering the intricate electrical wiring in the Solar Roof. Another restriction for flat Solar Roofs may also be that the colored louvers from the solar tiles significantly inhibit production from a flat angle.
How does the durability of the solar tiles compare to conventional solar panels?
The Solar Roof has a warranty of “infinity, or the lifetime of your house, whichever come first.” Tesla clearly is confident in the durability of the tempered glass tiles. These claims, obviously unproven at this time, are supported by the company’s entertaining videos of the tiles being pummeled by hail cannons in slow motion.
How does this compare to conventional solar panels? Standard solar modules are usually warranted by the manufacturer for 25 years, and will typically last much longer. Panels consist of a glass layer on top, a protective backsheet on the bottom, and an aluminum frame to protect the individual solar cells inside.
Tempered glass is up to six times stronger than regular plate glass. In fact, the material is already used in most, but not all, solar panel brands. Some cheaper panel manufacturers will use regular plate glass instead to cut costs. However, LG, SunPower, Canadian Solar, Hyundai and other large manufacturers all use tempered glass.
A comparison video of a Solar Roof tile and a tempered-glass solar panel being shot at by hail cannons and other heavy objects would quickly reveal the winner in this category. Until then, we’ll never know which one is actually more durable, because they are made of the exact same material and there aren’t any more details available at this time.
One factor that has not been discussed enough is how the solar components of the Solar Roofs will be replaced after the production degrades too much. Useful solar production is guaranteed by Tesla to last 30 years. Whereas regular panels could be easily replaced after this time, it’s likely going to be an expensive and labor-intensive process to retrofit Solar Roofs.
Who should get a Solar Roof?
By and large, Tesla’s Solar Roof will appeal to wealthy, tech-savvy homeowners with a passion for the environment but a disdain for the aesthetics of standard solar panel systems. These homeowners will also understand the relative risk of being an early adopter of these systems, but are still excited to be the first to experience the technology. Details like the ITC and final system cost are still unknown, so these homeowners will need a significant surplus of spending money. They’ll also.- most importantly.- need to possess a healthy level of patience, as it could be years before the system will be installed.
Overall, Tesla’s Solar Roof has and will continue to inject excitement into the solar industry, which has had its fair share of bad news these past couple of months (American module manufacturing, in particular, has been hard hit). The fact that so many media outlets and interested consumers are talking about BIPV again means that this technology is moving in the right direction.
Elon Musk himself has admitted that the Solar Roof will have significant challenges in the coming years, particularly in ramping up production to bring down and service more territory. Building a vertically integrated national roofing company is a huge challenge by itself, and he recognizes the Solar Roofs won’t be widely available for five or maybe even 10 years to come.
If you’re one of the lucky first few to have a Solar Roof installed on your home, invite us over!
Max Aram is the co-founder and CEO of Pick My Solar, an online platform for comparing solar companies.