Tesla Solar Roof Efficiency Revealed


Tesla Solar Roof Efficiency Revealed

As solar panel efficiency and the technology behind it continues to advance, you may be looking to equip your home with solar energy devices like Tesla’s Solar Roof. Tesla has been offering their Solar Roof since 2018 and is now on their third version/update of the Solar Roof.

The Tesla Solar Roof efficiency is near 17-19%. Tesla does not publish an efficiency for the Solar Roof. Not all tiles in the Solar Roof have solar cells in them. To determine an accurate efficiency, only the solar tiles with solar cells should be considered in the efficiency calculations.

Only the amount of solar tiles with solar cells needed to power the house are installed to reduce the overall cost of the Tesla Solar Roof. The rest are non-solar tiles. Understanding Tesla’s Solar Roof, what solar efficiency is, and why it is important can help you determine if it is best for you. Read on to learn more.

Solar Efficiency of Tesla Solar Roof

The efficiency of the Tesla Solar Roof ranks well compared to the efficiencies of solar panels. At 17-19% efficiency, the solar tiles are near the top efficiency possible with today’s solar technology.

Version 3 of the Tesla Solar Roof offers many improvements over the first and second version:

  • Solar efficiency improvements
  • Larger tiles
  • Lower overall cost

When calculating solar efficiency, it is important to understand that not all solar tiles in the Solar Roof contain solar cells. This is because extra solar tiles with solar cells are not needed if only a third of solar celled tiles is plenty to power the house.

How Is Solar Efficiency Calculated?

Solar efficiency is calculated by dividing the power input by the power output. The power input is the power provided by the sun. On a bright and sunny day, you can estimate the power from the sunlight at 1,000 watts per square meter.

To determine the power input to your Tesla Solar Roof, you will need to measure the area of all solar cells in the solar tiles, add them together to determine the total area in square meters. Next, you need to do the following:

  • Multiply the total area of the solar tiles by the power per square meter of the sunlight (1,000 watts per square meter on a sunny day)
  • Measure or find the power output from your Solar Roof

Alternatively, you can find the power output in the Tesla app, so this step is easy. Next, divide your power input by the power output and multiply by 100. You now have the (percent) efficiency of your Tesla Solar Roof.

To determine the solar efficiency of each solar tile, you could use its rated output of 24 watts for the calculation. Again, you would need to know the area (length times width) of the solar cell in the solar tile to correctly calculate the efficiency.

Components of Tesla’s Solar Roof That Boost Efficiency

Tesla’s Solar Roof is the solar shingles/tiles and electrical inverter system that SolarCity Corporation manufactures to high-efficiency standards. SolarCity is a subsidiary of Tesla, but the SolarCity name is not frequently marketed with the Solar Roof. Instead, it is commonly referred to as the Tesla Solar Roof.

SolarCity also makes and designs solar panels for Tesla and is based in Fremont, CA, with its main manufacturing center located in Buffalo, NY. The Tesla solar panels have a great efficiency rating too.

In 2016, Tesla purchased SolarCity, and all SolarCity products and services are sold through Tesla. By 2018, Tesla launched their first generation of the Solar Roof. Just over one year later, in October of 2019, Tesla released version 3 of the Solar Roof with a tremendous improvement in solar efficiency. Version 3 has the following improvements:

  • Manufacturable at a large scale
  • More cost-effective to make
  • Better efficiency
  • Low cost for the consumer

After launching version 3 of the Solar Roof, Tesla’s sales were projected to increase substantially if it were not for the coronavirus recession beginning in March 2020.

The Solar Roof

Tesla’s Solar Roof is not a standard roof with solar panels because the roof is the solar panel. The tiles/shingles themselves have photovoltaic energy-producing cells (solar cells) built into the tiles. Therefore, since they are smaller than a full solar panel, you can see why their efficiency is not as good as full-on solar panels.

The shingles/tiles of the Solar Roof are made to stack and install together to provide as much efficiency as possible. They install much like a standard roof tile does. However, they are made of a different, stronger material that can absorb sunlight.

Tesla Solar Tiles

Tesla solar tiles are made out of a special type of glass that can accommodate the solar cell being installed inside of it. The solar tiles are a dark black color- black and dark colors absorb more sunlight and solar energy than lighter colors. This is the same reason why most solar panels are black.

The Tesla solar tiles are made from a building-integrated photovoltaic (BIPV) solar cell. Building-integrated means it integrates/attaches to the building, and photovoltaic refers to the conversion of solar radiation to voltage.

The glass used in the Tesla solar tiles are very durable, come in large sections, and are easily mass-produced. This lowers the cost for the consumer, making it more affordable. The solar tiles are light and can withstand harsh impacts. Here are some downsides of the solar tiles:

  • They are harder to cut than standard tiles
  • They are smooth, and you can slip on them easily
  • Rain sounds louder on them since they are a harder surface

The glass and the solar cells within the solar tiles that make up the Solar Roof are designed in such a way to make its solar efficiency as good as possible. The engineered system is fine-tuned and balanced to provide efficient conversion of solar energy to DC electricity.

Tesla Inverter and Its Efficiency

The Tesla solar inverter collects the solar energy from the Tesla Solar Roof and converts it from DC power to AC power to provide the energy from the sun to your home. The Tesla inverter is a required component of your Solar Roof and will be installed at the same time.

The Tesla inverter also has its own efficiency. It is the efficiency of converting the DC energy provided by the Solar Roof to AC power needed to power your home. The inverter efficiency is a whopping 97.5%.

That is almost 5x more efficient than the Solar Roof? What is up with the large difference? Here is why:

  • It is challenging to convert sunlight to energy
  • Humans have been converting DC to AC power for many years, with constant improvement

Excess Energy

The inverter also has some useful additional features. For example, if your Solar Roof is generating too much energy that can be used by your house, the inverter will send the overflow energy off to the power grid.

If your solar efficiency is so great and you produce extra power, most utility companies will provide you a credit for the amount of extra energy your Tesla Solar Roof generates. This is a nice way for you to make a few extra dollars. All you have to do is let your house sunbathe!

Multiple Inverters

Depending on the size of your roof, the square footage of your house and roof, and the amount of energy consumption of your home, Tesla may install more than one inverter with your Solar Roof.  Having more than one inverter has some benefits:

  • Allow you to process energy more quickly (if there is too much supply for your home)
  • Marginally improve the overall efficiency of the Tesla Solar Roof System
  • Charge your Tesla Powerwall and/or Tesla car faster

The inverters convert the energy during the day when the Solar Roof is being hit with sunlight. It also provides energy to your home at night when there is no sunlight if you have a Powerwall battery.

Ensuring You Always Have Power

If you experience multiple cloudy days in a row, your Tesla Solar Roof will probably not provide enough solar energy to power your home. When this happens, your inverter will pull energy from:

  • The power grid
  • Tesla Powerwall

The Tesla inverter helps regulate the energy from your Tesla Solar Roof and the power grid into your home to ensure you have power at all times.

  • The Tesla Inverter converts solar energy from DC to AC power efficiently
  • It has a 97.5% efficiency – meaning 97.5% of the DC energy collected from the Tesla Solar Roof is successfully converted to AC power for use in your house
  • The inverter can be installed indoors or outdoors
  • It can provide 3.8 kW of energy (or 7.6 kW with the larger model)
  • It has a small profile of 26”x16”x6” (HxWxD)

Tesla Powerwall

The Tesla Powerwall is not a required component of your Tesla Solar Roof like the inverter is. However, it is a good combination. The Tesla Powerwall is essentially a large battery that stores energy to be used during power outages.

Think of the Powerwall as a backup generator- that is exactly what it is, after all. If your solar system is producing more energy than what you can use on a given day, you should incorporate a Tesla Powerwall to improve the efficiency of your overall Tesla Solar Roof system.

It is very inefficient to lose the extra energy you produce! Especially if you are providing it to the rest of the power grid for free!

In fact, the Tesla Powerwall has many advantages over traditional gasoline or diesel power generators, such as better overall efficiency.

What Are Tesla Solar Panels Made of to Make Them so Efficient?

The Tesla solar tiles are made from black tempered glass with embedded solar cells. The glass boasts a strength rating of 3x stronger than standard roofing tiles. The shape of the Solar Roof panel is designed and manufactured to look similar to standard roofing tiles and provide great solar efficiency! Recall, the efficiency of the panels is 17-19%.

Not every tile in the Tesla Solar Roof has a solar cell- there are non-solar tiles and solar tiles in the Solar Roof. The solar tiles and non-solar tiles look exactly the same from a distance, like from your yard or the street.

You can only tell the difference when you are looking closely. You will be able to identify a solar tile containing a solar cell by noticing:

  • An embedded circuit board under the layer of glass
  • Thin wires running through the glass tile

During the design process of your Tesla Solar Roof, the amount of solar cell containing solar tiles for your roof will be determined based on the square footage of your roof, geographic location, size of your home, and the energy usage of your home. If you live in a sunny area, your Solar Roof may have fewer solar tiles than one in a cloudy area.

What Exactly Is Solar Efficiency?

Solar Efficiency refers to the amount of sunlight radiation that could be converted to useful electricity or power by a solar cell. In the case of the Tesla Solar Roof, the solar cell is located in the solar tiles that make up the roof.

A solar cell is a photovoltaic membrane that does the conversion of sunlight radiation into electricity! The amount of power output and the efficiency of a solar cell is directly related to the amount of sunlight it receives.

Where the sun is located in the sky is a large factor in efficiency too:

  • If the sun is high in the sky, like it is during the summer months, the efficiency of the solar cell and your Solar Roof will be greater
  • If the sun is lower in the sky, like it is during the winter months, then the efficiency will be lower.

There are a few factors that can reduce the efficiency of a solar cell or your Solar Roof:

  • Dust accumulating over the solar cell because it blocks sunlight
  • Shade from trees
  • Leaves, branches, and other debris collecting over the solar cells
  • Degradation of the solar cell over a long period of time

Ways to Improve Efficiency of Solar Cells

There are ways to increase the efficiency of solar cells. The main methods involve creating more layers of the solar membrane, reducing reluctance, creating better charge carrier separation, and improving thermodynamic efficiency. These terms are all pretty technical sounding, so we will leave them for the scientists.

To improve the efficiency of your Tesla Solar Roof, you will want to make sure it is clean and clear of any dust, leaves, or other debris. You will also want to routinely monitor it in the Tesla app to be aware of any decreases in energy production- a sure sign of efficiency or other issues. If you do notice large changes, contact Tesla support.

How Does the Tesla Solar Roof Compare to Solar Panels?

Tesla’s Solar Roof has many differences from traditional type solar panels. Traditional solar panels are usually attached to the roof of the house but can also be installed on the ground. The differences between the two are many.

  • The Tesla Solar Roof has more curb appeal than solar panels. Solar panels installed on a regular roof look ugly, while the Solar Roof looks just like a standard roof.
  • Tesla Solar Roof protects your home. The Solar Roof is very strong and provides great resistance to hail damage, wind damage, and more.
  • Tesla Solar Roof efficiency is slightly lower, but nearly the same as solar panel efficiency.
  • Tesla Solar Roof costs less than a traditional new roof plus traditional solar panels.
  • Tesla Solar Roof requires less maintenance than solar panels, especially those installed on traditional roofs. Installing a new roof with an existing solar panel adds costs to the installation.

How Does the Tesla Solar Roof Compare to Competitors?

Believe it or not, the Tesla Solar Roof has at least two major competitors in the US. While they all have their differences and unique styles, they are all producing solar energy for residential homes. The competitors are:

  • CertainTeed Solar in PA with their Apollo Ii Solar Roofing System
  • Luma in MI with their Solar Luxury Roof System

Unfortunately, neither company publishes the efficiency of their Solar Roof. CertainTeed refers to the Apollo II as having “high efficiency,” whereas Luma only mentions the power output of their Luxury Solar Roof.

Since solar cells have minute differences in solar efficiency these days, you should be able to safely estimate the solar efficiency of both Luma and CertainTeed close to the Tesla Solar Roof. The only sure-fire way to know would be to test them out and calculate it, have fun!

Advantages of Tesla Solar Roof

Tesla’s Solar Roof has plenty of advantages. You may even be surprised to learn that the advantages are not related only to energy savings. The Solar Roof is beneficial to your home from a maintenance, energy, cost, and profitability standpoint.

  • The Tesla Solar Roof is an efficient way to get solar energy to your home.
  • Tesla Solar Tiles are up to 3 times stronger than standard roof tiles/shingles. They protect against damage from hail, fallen branches, and other impacts. Preventing leaks and costly repairs will save you money.
  • The Solar Roof provides your home with free passive power. After paying for the installation and materials, the energy from the sun you are collecting is free!
  • Easily monitor your home’s power consumption, solar energy input, and extra energy you are providing to the power grid easily with the Tesla app. You can notice and correct unexpected high power usage quickly.

You can also integrate easily with Tesla’s home battery backup system – the Tesla Powerwall. You will never be without power again with the Powerwall. It works easily with the Solar Roof and stores energy for use during power outages.

Advantages Over Traditional Roofs

It also has advantages over traditional roofs:

  • Longer lifespan of your roof. Tesla provides a 25-year warranty on the Solar Roof. Elon Musk has even claimed the Solar Roof will last the lifetime of the home (or longer). Having to replace your roof less often could save you tens of thousands of dollars in the future.
  • Tesla Solar Roof weighs less than standard roof tiles/shingles. This means they cost less to transport and ship to your home.
  • The Tesla Solar Roof can make you money from your utility company! If you have excess power, your local utility company could buy the extra energy from you by providing you a credit on your utility bill.
  • Federal solar tax credit. You can qualify to receive a discount on your new Tesla Solar Roof in the form of a tax credit through the US federal government. In 2021, the tax credit is 22% of the cost of the solar system.
  • State tax credits. Many US states offer a solar tax credit too!

How Much Will the Tesla Solar Roof Save You on Your Electrical Bill?

Tesla’s great webpage also provides an estimate on how much your electric bill will be reduced too! You provide them with your average monthly electric bill, and they perform an estimate based on your geographic location (how much sunshine you get).

The estimated savings are based on the average power that a 7.8kW Tesla Solar Roof can produce and the average energy cost in your state for the last 25 years. Your cost savings will vary depending on your location, how much sun you get, and the energy cost in your area.


For a midwest location, 2000 square foot home, with an average monthly energy bill of $150, you can expect to save around $105 each month. This is a fantastic reduction to the electrical bill!

These cost savings are all estimates- the more efficient your Solar Roof is, the more you save on your electrical bill! So remember to keep it clean, cut back trees, and make sure it is operating properly.

How Long Will It Take for a Tesla Solar Roof to Pay for Itself?

It will take time for the Tesla Solar Roof to pay for itself. The break-even time will likely be several years, on average around 10-15. The break-even point is the time it will take for the money you save on electricity to equal the money you spent on the Tesla Solar Roof installation.

If you keep your Solar Roof clean, in good shape, and cut back trees causing shade coverage, you will maximize your Solar Roof efficiency and get to the break-even point much more quickly!

For example, you spend $16,000 total (after tax credits) to have your new Tesla Solar Roof installed. Say the Solar Roof lowers your energy by on average $100 a month. How many months will it take for $100 savings to equal $16,000? Ultimately, you get a break-even period of 160 months or 13 years and 4 months.

If you improve your Solar Roof efficiency by routinely cleaning it and cutting out shady trees, you can reduce your break-even period by months or even years! Here are the 3 main takeaways on the break-even period:

  • The break-even period is the amount of time it takes for your monthly savings to equal the money you spent/invested
  • To calculate your break-even period, divide the money spent by your cost-savings per month or per year
  • Tesla’s website will calculate the break-even period for you when you arrange an installation or get a quote

Can You Monitor or Optimize the Efficiency of Your Tesla Solar Roof?

You might have heard of the Tesla smartphone app and are curious about its capabilities. After downloading the Tesla app and connecting it to your Solar Roof/inverter system, you can monitor the energy production from your Solar Roof through the My Home section on the app.

If you keep an eye on the energy production throughout the week, you will be able to notice any drastic changes in solar efficiency. If there are large changes that are not the fault of a cloudy day, make sure your roof is clear, and then call Tesla support if you need additional troubleshooting assistance.

With the Tesla app, you can see the daily, weekly, monthly, and even yearly trends of the solar energy production of your Tesla Solar Roof. You can also see the amount of power you are providing back to the utility company and your Tesla Powerwall (if you have one or more).

The Tesla app also integrates with your other Tesla products, such as your Tesla cars, if you own any. If you have a Tesla car and the Tesla Solar Roof, you could further reduce your carbon footprint by powering your Tesla car with the power of the sun! Imagine charging your Tesla Model S with your Tesla Solar Roof, now that is efficient!

Conclusion

The Tesla Solar Roof’s efficiency is estimated at around 17-19%. Its efficiency is up to current technological standards. The roof also has a long lifespan, it is durable enough to protect against impacts from hail, and it provides cost savings on your electrical bill.

You can improve your Tesla Solar Roof’s efficiency by keeping it clean and ensuring nothing is providing shade over the roof. Using solar energy is much better for the environment than fossil fuels and could help slow down climate change. And you can easily store backup power with the Powerwall, maximizing your system efficiency.

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Greg

Hi, I'm Greg. My daily driver is a Tesla Model 3 Performance. I've learned a ton about Teslas from hands-on experience and this is the site where I share everything I've learned.

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