Tag Archives: Tesla Powerwall

An Inside Look At The Components That Go Into A Tesla Solar Roof Installation

Originally published on CleanTechnica

July ushered in the start of the real action for our Tesla solar roof, as the installation kicked into high gear. The first materials arrived at the house and the team prepared to install the solar roof on our new home. Before we get into the installation, let’s talk about the components that make up of one of Tesla’s solar roofs.

Tesla solar roof installation. Image credit: Chuck Field

Many of the components and processes used in installing a Tesla solar roof are from the traditional roofing industry, which makes sense. The solar roof still fundamentally has to perform all of the same functions of a normal dumb roof before its ability to generate power matters. It also includes many of the same components as a traditional bolt-on solar system, with rooftop wiring, inverters, safety devices, and the like.

Underlayment

A Tesla solar roof installation starts with the installation of a waterproof underlayment. Tesla uses Firestone’s CLAD-GARD SA-FR, a standard roofing underlayment for metal roofs. This product provides a waterproof foundation for any roof while also providing a skid-resistant surface for the installers to walk on while installing the more complex parts of the roof. This is the white material in the photo above.

Metal Framing

After the underlayment goes down, Tesla’s crew frames up the roof with metal. A metal trim wraps around the entire roof edge as well as along every peak and valley in the roof structure. In the valleys of the roof, the metalwork provides the drainage for any precipitation and debris. Up at the peaks of the roof, it provides protection, funneling any precipitation onto the tiles or surfaces below, which ultimately escort it off the roof.

Tesla solar roof with copious amounts of metal work framing the roof. Image credit: Kyle Field | CleanTechnica

Tesla makes all of its own metal products for the solar roof, so all of these components are specific to the Tesla solar roof. Word on the street is that these are all currently made in the Bay Area, but that likely won’t be the case as Tesla ramps up production after locking in the design of version 3 of its solar roof tiles.

Roof Tiles

The star of the show in the solar roof install is obviously Tesla’s solar roof tiles. These come in two flavors: 1) tiles with solar cells sandwiched between two pieces of tempered glass that produce power, and 2) glass tiles. Roof tiles with solar cells in them are called PV Tiles and are the fundamental building block of any Tesla solar roof. They arrive on site in pre-wired, pre-mounted bundles of 3 tiles in a row, called PV Modules.

A pallet of Tesla PV Module roof tiles. Image credit: Kyle Field | CleanTechnica

Each PV Tile has a production capacity of just over 8 watts each, translating to 25 watts for a full 3-tile PV Module. Assembling the tiles together into PV Modules at the factory has multiple benefits, with the first and foremost being a reduction in the amount of effort and time that’s required to install a solar roof. This helps Tesla deliver a faster turnaround time, means less time for a customer’s home sitting there without a roof, and keeps labor costs down.

Using PV Modules also reduces the number of on-site wiring connections that need to be made, allowing Tesla to control the quality of more potential points of failure in the roof system at the factory. PV Modules come with the joints between the three tiles pre-sealed, resulting in what is surely a higher quality, more consistent seal that what can be guaranteed with a field installation. Each PV Tile comes with its own set of built-in c-clip mounts and stand-offs that hold the top of the tile off of the roof, transferring any weight from above to the roof surface below while also serving to set the correct angle to allow water to run down the roof.

Tesla calls the non-producing tiles Roofing Tiles, which are simply made from a single sheet of tempered glass. These come from the factory as single tiles as well as bundled into Roofing Modules comprised of 3 glass tiles. Tesla uses these on sections of the roof that are not wide enough for a block of solar tiles and for use along the seams of the roof. To ensure a clean fit at the seams, Tesla’s team simply cuts the tiles to match the angle of the seam they will butt up against.

A cut Roofing Module with mounting bricks in the background. Image credit: Kyle Field | CleanTechnica

Mounting Bricks

Tesla has packed an impressive amount of functionality into each single PV Module, and the mounting bricks are the other half of the system that makes it easy for Tesla’s installer to secure the PV and Roofing Modules to the roof. Tesla’s mounting bricks come in standard and drained configurations.

Tesla solar roof installation. Image credit: Chuck Field

Standard mounting blocks allow the tile below it to mount to it, but also allow the panel above it to clip to it, thanks to a healthy dose of industrial grade plastic hook and loop. The trailing edge of the panel above the mounting brick has another strip of this fabric, resulting in a very secure bond. Check it out in the video below:

Drained mounting bricks include a channel that helps water drain in the proper direction between each of the PV Modules or where they butt up against a Roofing Tile or Roofing Module. They still allow adjoining modules to mount to them with their c-clips, but with the added benefit of funneling water down the roof.

A Tesla solar roof tile clipped onto a drained mounting block. Image credit: Kyle Field | CleanTechnica

The Electrical System

Each PV Module is connected to the solar roof wiring string via standard solar MC connectors that come pre-installed from the factory. These strings then connect down through the roof via a series of electrical pucks mounted and sealed to the roof. Tesla is required to install a Rapid Shutdown Device (RSD) within 5 feet of every solar array, so they are typically installed up in the rafters near the roof.

The wiring in an array of Tesla solar roof tiles. Image credit: Tesla

On the inside of the house, the pucks sprout bare wires that connect to one of a handful of these Delta Rapid Shutdown Devices, shown as a small grey box to the right of the rooftop wiring in the image above. Outputs from the RSDs are fed down to a pair of Delta inverters that convert the DC power from the roof down into the AC power that all the electrical goodies in the home want.

From there, the wiring configuration varies depending on whether Powerwalls are being installed or not. We are installing two Powerwalls, so we’ll talk through the essential loads wiring configuration. For our house, we do not have anything running on gas, so all our appliances, cooking, and heating are electric. Add to that two electric car chargers and a spare for guests and our loads were just too large to cram into a single 200 amp electrical sub-panel.

After all the load calculations were done, we opted to pull a few of the larger, less critical loads off of the Powerwall battery backup and just backup the “essential” loads in our house. The image below shows a single, undersized inverter and diminutive supporting boxes. Every single one of these boxes/devices in our system is twice as large as shown here, with the exception of the Tesla Powerwall (though, technically, we do have two of those).

Image credit: Tesla

The two Powerwalls provide backup power to everything on our 200 amp sub-panel, while the remaining loads in our home — our electric oven and two of our car chargers — will be relegated to the 400 amp main panel.

The Tesla Backup Gateway provides communication to the Tesla Mothership and can automagically disconnect the home from the grid in the event of a power outage. Doing so engages the Powerwalls to provide power to all of the essential loads in the sub-panel, while being replenished by the rooftop solar system when the sun is out.

That’s an overview of the components in a Tesla solar roof system. We’ll dive into the system more in future articles, so stay tuned for a first look at this hot new clean tech.

Why Tesla’s Solar Roof Is A Bargain, 53% Of The Price Of A Roof + Electricity

Image courtesy: Tesla

Originally published on CleanTechnica

When Tesla CEO Elon Musk unveiled the company’s Solar Roof tile system back in 2016, he boldly proclaimed that it would cost less than buying a roof and electricity. Since then, we have not seen any data to support his claim, until now.

I signed a contract with Tesla for the installation of a new Tesla Solar roof tile system and have unpacked the details, good and bad, from the contract in a series of articles. To kick things off, I will start by comparing the cost of the system against Elon’s claims to see if a Tesla Solar Roof tile system is actually cheaper than buying a roof and the power generated by the system over its life.

One Roof To Rule Them All

An accurate comparison requires an accurate baseline to be used for the cost of electricity and the cost of a new roof. Getting a new roof installed can range from $10,000 to $50,000, depending on the material used. Composite shingle roofs and tile roofs are more cost effective, but do not have the same durability as a Tesla Solar Roof with its tempered glass tiles. Tesla’s Solar Roof  is comprised of, “Glass solar tiles are so durable they are warrantied for the lifetime of your house, or infinity, whichever comes first.”


The only roofing product on the market that comes close to this bold proclamation is a metal roof with an expected 50 year life. This is an important comparison to understand because just looking at the Tesla Solar Roof as simply the covering for the home already sets it apart from most common roofing products. It is a high-end roof, even without the solar aspect. This is not a justification for a higher price, but it is simply the reality of buying a roof that lasts.

The Tesla Solar Roof is not a typical roof, and that is highlighted in the fact that it comes with two different guarantees. The first is for the solar production from the roof. The solar production from the Solar Roof is guaranteed for 25 years. This protects the buyer from subpar solar cells, cells failing, or other factors that impact the electrical generation from the system. Such a guarantee is standard across the solar industry. The second warranty is for the physical roof structure. Because the Tesla Solar Roof is a building-integrated photovoltaic (BIPV) system, in addition to generating power, it also must serve as the physical roof for the house. As a roof, the Tesla Solar Roof is warrantied for infinity or the life of the home, whichever comes first.

To ensure accuracy, I went out and got bids for the job from 5 real local contractors in Southern California. This was not a hypothetical exercise, as we are in need of a new roof and were actively pursuing both options to determine which was a better fit for our family. Bids were made based on actual permitted architectural drawings of the roof, with all associated wrinkles and warts. After receiving all of the bids, I took the average price from all 5 contractors and used that as the baseline cost for a comparable roof installation. That came to $37,865.80 for a new metal roof.

Electricity By Any Other Name

Musk and his team of energy engineers at Tesla were not simply trying to build a better roof. They were ultimately trying to build a solar product that would help the masses to adopt solar because it was easier, cheaper, higher quality, and better looking. That is a tall order to fill, by any measure.

On the cost side of the equation, it is a simple matter of taking the cost of electricity from the U.S. Energy  Information Administration (EIA) and extrapolating that price out over 25 years. I used the most recent cost of residential electricity in California of 19.3 cents/kWh (March 2019) and extrapolated that out using a conservative 2% annual increase. For parity, I priced the system out using the production of the solar system, following the maximum degradation noted by Tesla. Over the 25 year warrantied life of the solar production from the system, the Solar Roof system should generate $73,436.14 worth of electricity.

Sizing The Solar Roof

We do not have a gas line running to our home, so everything in the home runs on electricity. We also have two electric vehicles that pull the vast majority of their electricity from our home. To offset as much of this consumption as possible, we are installing the largest Tesla Solar Roof tile system that our roof can handle.

System sizing on a Tesla Solar Roof is done differently than traditional solar systems, where the number of solar panels used depends on the need and roof capability. Because a Tesla Solar Roof has to serve as a physical cover for the house as its primary function, tiles must cover the entire surface. To size the system, Tesla has developed tiles that have solar cells and tiles that do not — and they all look essentially the same. For smaller systems, Tesla simply uses fewer tiles containing the actual solar cells.

Image courtesy: Tesla

The Tesla Solar Roof for our home has solar cells in every location possible. There are some areas around the edges of the roof and near the hips and joints without cells, but every other surface is setup to produce power. The primary surface of our roof faces south, which is ideal for solar production, but the configuration we are using utilizes the north-, east-, and west-facing roof surfaces as well. That does indeed maximize our solar generation, but results in a lower yield from the system compared to a system with all active tiles facing south.

The Data

All told, Tesla was able to fit a 10.59kW system in our roof, which it expects will produce 13,126 kWh in its first year of operation. This is the equivalent size of a system of 32 x 330 watt solar panels! The system, which I’ll remind you also serves as the roof for our home, came out to $70,375.23 before rebates and $58,603.04 after rebates. Compared to the cost of a metal roof, the Tesla Solar Roof was $20,737.24 more.

Translating this data into nerd-speak, aka an Excel spreadsheet, we can see that the cost of installing a metal roof and simply buying the equivalent of the electricity produced by the Tesla Solar Roof system would equal $111,301.94, whereas the Tesla Solar Roof is only $58,603.04. These are not hypotheticals or mythical numbers, just a simple summary of expenses in two different scenarios over 25 years. Said another way, the Tesla Solar Roof is 52.7% of the cost of installing a comparable roof and just buying power from the utility.

What About A Composite Shingle Roof?

Image courtesy: Tesla

Costing out a Tesla Solar Roof versus a metal roof is interesting, but that’s still a really expensive roof. Musk said at the company’s annual shareholder meeting on June 11th, 2019, that the Solar Roof team was really pushing to beat even the ubiquitous composite shingle roof. Using the single estimate we received for a composite shingle roof for our house at a mere $12,000, the Solar Roof system still comes out on top.

We can use the same $73,436.14 for the value of the electricity produced and $12,000.00 for the composite shingle roof for a total of $85,436.14. That includes the cost of electricity over the life of the system from the utility and the physical composite shingle roof. Compared to the $58,603.04 for the Solar Roof, composite shingle is already more expensive here in Southern California.

In fact, even if I throw in the roof itself as free, the Solar Roof is cheaper than simply buying power from the utility here in California, for a savings of almost $15,000 over 25 years. It won’t make or break your retirement, but it is impressive to see that the Solar Roof is already holding its own against roofing materials of any type in California. In fact, that is conveniently close to the installed price of two Tesla Powerwalls, so throw those in for some extra resiliency and call it a day.

The payback time for the Solar Roof will vary state by state and utility by utility, so be sure to run your own numbers before pulling the trigger on your own system. We spent months looking into this topic. Check back at CleanTechnica for more analysis of the Tesla Solar Roof system as the installation of our system progresses.

If you are in the market for a Tesla, find someone locally who you know (like, someone you know in real life) and use their referral code. If you don’t know anyone with a Tesla, go find someone at your local Supercharger and try not to be a creep and ask them for their referral code (they won’t mind). If that doesn’t work, ask a co-worker or a distant relative, post on Facebook or Twitter, or just hit up Google. If all of that fails and it’s an odd-numbered day and not too sunny out, you can use my Tesla referral link to get 1,000 miles of free Supercharging, I guess. Here is my referral code: http://ts.la/kyle623