tesla powerwall review

The Tesla Powerwall home battery complete review

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Back in 2015, automaker Tesla Motors set its sights on the home energy storage market and announced the launch of its home battery product, the Tesla Powerwall.

In the past, Tesla Motors has been praised for making high-quality electric vehicles, as well as for their ability to reimagine and successfully rebrand existing technologies. In fact, while Tesla’s automobiles revitalized the 21st-century electric vehicle market, the first electric cars were invented more than a hundred years earlier. 

Tesla’s rebranding of residential-use batteries is in line with their legacy of reimagining existing products. Tesla’s battery may represent the first time in history that everyday homeowners are truly excited about the potential of storing energy at their home. The Powerwall, combined with the exciting Tesla Solar Roof, are both potential cornerstones of Elon Musk’s sustainable energy vision for the future.

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How the Tesla Powerwall works

The Powerwall pairs well with solar panel systems, especially if your utility has reduced or removed net metering, introduced time-of-use rates, or instituted demand charges. But, can the Tesla Powerwall power a home? In short, yes—installing a storage solution like the Tesla Powerwall with a solar energy system allows you to maintain a sustained power supply during the day or night, as long as you store enough solar power from your panels when the sun is shining.

As with many other home battery products, the Tesla Powerwall is sized for day-to-day use at your home and is often paired with a solar panel system. When your solar panels produce more electricity than you can use in your home, you can store the excess electricity in the battery system instead of sending it back into the grid. Later, when your panels aren’t producing enough electricity to meet your home’s needs, you can use the electricity stored in your battery instead of having to buy it from your utility company.

Key things to know about the Tesla Powerwall

Tesla describes the Powerwall as a “rechargeable lithium ion battery with liquid thermal control.”  It is one of a few companies in the residential energy storage market that makes small-scale batteries for home energy storage. The first-generation Powerwall launched in April 2015, and updated Powerwall 2.0 models were announced in October 2016 and November 2020.

When evaluating the Powerwall, there are various important metrics and technical specifications to keep in mind. Among the most important are the size of the battery (power and capacity), its chemistry, depth of discharge, and roundtrip efficiency

 Powerwall 1 (April 2015, discontinued)Powerwall 2 (October 2016, discontinued)Powerwall 2 (November 2020)Powerwall + (April 2021, includes integrated solar inverter)
Usable capacity6.4 kWh13.5 kWh13.5 kWh13.5 kWh
Continuous maximum power3.3 kW5 kW5.8 kW5.8 kW (no sun) / 7.6 kW (full sun)
Weight
214 lb251.3 lb251.3 lb343.9 lb
Dimensions51.3 in x 34 in x 7.2 in45.3 in x 29.6 in x 5.75 in45.3 in x 29.6 in x 5.75 in62.8 in x 29.7 in x 6.3 in
Operating Temperature -4 to 110°F -4 to 122°F -4 to 122°F -4 to 122°F

Size

The Tesla Powerwall comes in only one size of 14 kilowatt-hours (kWh). Two important metrics to keep in mind when comparing the Powerwall to other home storage options are power and usable capacity. Power (measured in kilowatts, or kW) determines the maximum amount of electricity that can be output at a single time, while usable capacity (measured in kilowatt-hours, or kWh) is a measure of the maximum amount of electricity stored in your battery on a full charge. The Tesla Powerwall boasts a maximum power rating of 7.0 kW to go along with 13.5 kWh of usable capacity

Importantly, the Powerwall system is also modular, meaning you can add multiple battery products to your storage setup. For example, you might want to install multiple Powerwall batteries for a home with high energy demands and usage. The Tesla website indicates that you can add up to 10 Powerwall batteries together to form one massive storage system.

Think of your battery like water running through a pipe. The usable energy capacity is the amount of water available to push through the pipe, while power is the size of the pipe itself. Larger pipes allow more water to flow through at once, which depletes the water faster. Similarly, a battery with a high power rating can deliver more electricity at one time, but will burn through its available energy capacity faster too.

A battery’s power determines what appliances you can run with it at the same time, while usable capacity determines how long those appliances can be run. Batteries with a higher power rating are capable of powering more robust appliances or many appliances at once, while batteries with a higher usable capacity can store more total energy and thus can run your appliances for longer periods of time without needing to recharge.

Basic functionality

The functionality of one solar power battery next to another can vary; some batteries have excellent off-grid capabilities, while others offer software solutions specific to rate arbitrage. Here are the important qualities of the Tesla Powerwall:

Backup power

Tesla has made a concerted effort to ensure their battery solution is compatible with most common brands and types of off-grid and hybrid inverters. This means that, as long as your installer installs the correct components, your Tesla Powerwall battery will be able to provide backup power for your home when the grid goes down.

Chemistry

The Tesla Powerwall is a lithium-ion storage product; specifically, it is a lithium nickel manganese cobalt oxide (NMC) battery. This is one of the most common lithium-ion battery technologies, and for good reason: relative to other types of batteries, NMC batteries are known for their high energy density (the amount of energy they can store relative to the physical space they take up) and increased safety. To learn more about how different lithium-ion battery chemistries stack up against one another, check out our overview of battery chemistry differences.

Performance metrics

Two key ways to evaluate the performance of a solar battery are its depth of discharge and roundtrip efficiency

Depth of discharge (DoD) indicates the percentage of a battery’s energy that has been discharged relative to the overall capacity of the battery. Because the useful life of a battery decreases each time you charge, discharge, and re-charge–or cycle–your battery, many battery manufacturers specify a maximum DoD level for optimal battery performance. In general, batteries with a higher depth of discharge are considered better quality products. The Tesla Powerwall boasts a depth of discharge of 100 percent, reflective of its remarkably safe and advanced NMC battery chemistry.

Roundtrip efficiency is a measure of electrical losses involved with charging and discharging a battery. The higher the efficiency percentage, the more efficiently the battery is able to convert incoming electricity into stored electricity and then back into usable electricity. The Tesla Powerwall has a high roundtrip efficiency of 90 percent; this means that for every 10 kilowatt-hours (kWh) of electricity you put into the battery, you’ll receive 9 kWh of output.

Tesla Powerwall warranty coverage

Tesla Powerwall warranties


  • Warranty period: 10 years
  • Guaranteed end of warranty capacity: 70%

In most cases, homes with a Tesla battery will charge and discharge their battery every day. So, how long do the Powerwall batteries last? The Powerwall comes with a 10-year warranty, and Tesla guarantees that the battery will maintain at least 70 percent of its capacity to hold a charge during that time period. 

Tesla’s battery technology is similar to other rechargeable batteries both large and small: as time goes on, the battery loses some of its ability to hold a charge. Think of how the battery life of a brand-new smartphone compares to one that is a few years old. As you continually charge and drain your phone’s battery, it starts to lose some of its ability to hold a charge.

The battery life of your Powerwall battery will deteriorate in the same way. That isn’t an indicator of a product flaw – all batteries lose some of their ability to hold a charge over time after extended usage, whether it’s an electric vehicle battery, a home energy battery, or a rechargeable AA battery. This is why Tesla offers a warranty that guarantees a certain percentage of storage capacity ten years in the future.

If you want to compare individual battery models side-by-side, our battery Buyer’s Guide lets you select products and compare them based on efficiency, capacity, power, and more.

How much does a Tesla Powerwall cost?

The cost of a Powerwall stands at $7,500 alone, and its supporting hardware costs $1,000, bringing the Powerwall cost and its associated components to $8,500 before installation.  On EnergySage, the Tesla Powerwall cost generally ranges between $12,000 and $16,500 for a full system installation (before incentives and taxes). That number includes the battery, an inverter, various other equipment costs, and estimated installation costs. The cost of installing a battery isn’t as straightforward as looking up the list price for an individual component–i.e., your battery. In fact, depending on your electrical setup, among other factors, installation costs can vary widely.

If you want to install the Powerwall as part of a solar-plus-storage system, the actual Tesla Powerwall cost is just one part of the equation. A 5 kilowatt (kW) solar energy system costs anywhere from $9,000 to $15,000 depending on where you live and the type of equipment you choose.

ProductPrice
Powerwall 1 (April 2015, discontinued)$3000
Powerwall 2 (October 2016, discontinued)$5,500 to $6,500
Powerwall 2 (November 2020)$7,500
Powerwall + (April 2021, includes integrated solar inverter)$8500

That may sound like a lot of money, but installing a solar-plus-storage system and Tesla Powerwall can be a worthwhile investment. Whether or not the Tesla Powerwall makes sense for you is determined by the way that your electric utility structures its rates, as well as your reasons for installing a solar power battery. For example, if you want to become energy independent and are able to install several Powerwall batteries to increase energy storage capability, then investing in one is worth the time and money. It can also provide peace of mind during outages and natural disasters, and it can minimize your carbon footprint.

In some cases, depending on where you live, you may have access to financial incentives that can reduce your home energy storage installation costs. For instance, if you live in California, you could get a cash rebate that covers most of your home battery costs through the Self-Generation Incentive Program (SGIP). Other states (such as Massachusetts) are in the early stages of evaluating battery storage performance incentives as well, and several states already provide cash rebates to offset the Tesla Powerwall Cost.

Can you go off-grid with the Tesla Powerwall?

Installing a solar-plus-storage system at your home is a great way to take control of your electricity bill, but it doesn’t mean that you’re completely disconnected from your utility. Going “off the grid” with solar batteries is actually a more expensive and complicated proposition than you might think. Most home batteries, including the Powerwall, only have enough capacity to store a few hours of electricity. If you want to make sure you can maintain power to your property for days at a time, you’ll need to install several Powerwall batteries together to increase your storage and usage capabilities.

Where to buy the Tesla Powerwall

The Tesla Powerwall battery is currently available online through Tesla’s website and through any solar and/or energy storage installation company that carries the Powerwall in their inventory. Adding energy storage technology to your home is a complicated process that requires electrical expertise, certifications, and knowledge of the best practices required to install a solar-plus-storage system correctly.

A qualified EnergySage-approved company can give you the best recommendation about the Tesla home battery system and other energy storage options available to homeowners today. If you are interested in receiving competing installation quotes for solar and energy storage options from local installers near you, simply join the EnergySage Solar Marketplace today and indicate what products you’re interested in your profile’s preferences section.

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About Jacob Marsh

Jacob is a researcher and content writer at EnergySage, where he focuses primarily on current issues–and new technology!–in the solar industry. With a background in environmental and geological science, Jacob brings an analytical perspective and passion for conservation to help solar shoppers make the right energy choices for their wallet and the environment. Outside of EnergySage, you can find him playing Ultimate Frisbee or learning a new, obscure board game.

64 thoughts on “The Tesla Powerwall home battery complete review

  1. Hampton Gardner

    I put up a deposit a couple of years ago and no one has contacted be back. I live in Mississippi I hac=ve bought Batterys from another company.. Im tired of waiting on Tesla. I want my Deposit Back how do I go about getting it back.

    Reply
  2. RECEP

    Is there anyone reach these data :How many parallel and series connection of cells in the Powerwall? Which brand of BMS and inverter inside the Powerwall?

    Reply
  3. Jose Maldonado

    Jacob, thank you for a most informative article. I do have a question for you, if I were your brother and was asking you for for advice, based on this scenario: family of 3, home size is 2,500 sq’, since the pandemic began mostly at home, have no electric cars (but plan to replace my wife’s car for a hybrid or fully electric in the next 3 years; I mostly bike to work); and thinking of replacing our water heater with an electric, on demand type in the next couple of years (currently gas). We installed solar panels last year- didn’t put in a battery, given the upfront cost and what I read about the relatively short battery life. Haven’t seen much savings between what I paid before and what I pay between gas and the cost of solar panels.

    Based on the above, how would you respond to the following:
    1. Is it really a worthwhile investment to instal a battery?
    2. If so, is the Tesla Powerwall what you would recommend, or are there other batteries I should look into?
    3. SunRun installed my system, are they the best to install the battery or should I look elsewhere (zip 94025)?
    Many thanks, jm

    Reply
  4. Min

    I guess, Tesla offer PW only offer for the current solar home. but, local installer only support with a solar.
    I have contacted couple of local solar company at NJ such as Sunrun. but, They do not offer on the current my solar system.
    So, I have choose DYI,

    Reply
  5. Doug

    What do you think of just the batteries. Get a electric rate reduction at night with a high rate during the day. Trickle charge all night cheaply when the rates are very low and then use the batteries during the day when the rates are very high.

    Reply
    1. MWD

      The short life span of even a great battery, like a Tesla, makes the savings nowhere near the cost of the battery with installation, especially if you use the 10YR – 70% numbers. So right now, you’ll never save as much as you will pay. Now if you live in Texas, or any other state with really high surcharging when demand is up, you might save the cost of a battery – but it would need a weird weather event that causes electricity prices to spike into the stratosphere, and if that happened one battery would only buy you a day or so off grid — if you don’t run any major appliances. So, short answer, no. It won’t even pay for itself this way.

      But if you live in an area that has frequent electricity shut down, or you really need to run life saving devices, the value of the whole house battery is not in any kind of financial savings for electricity itself. For a business that could lose valuable product if the freezers get too warm or the eggs get too cold, these kind of investments have an entirely different meaning. But until either the price of electricity gets much higher or the cost of batteries much lower, you won’t save as much as you spend.

      Reply
      1. Carl

        Many places such as hospitals already have back up generators on site that can power their entire location for extended periods of time. It seems like these batteries are a good idea but just way overpriced for what they are.

        A diesel generator with instant transfer switch is thousands of dollars less and obtains the same results, plus, the only unit that will eventually (after many years) require replacement will be the generator. With that said, I currently have a portable generator that we use when we lose power (only 7 kw generator) that plugs into a whole house transfer switch. While the process is manual and takes a little effort, the thousands of dollars of another system just isn’t worth it. The other benefit of the diesel generator is that the capacity does not diminish over time like any of the storage batteries.

        Then, there’s the disposal cost to consider. What will happen to all these batteries when it comes time that they are at their end of life? We all hear and talk about recycling but in reality, much of what goes out in the recycling stream is just trashed or improperly disposed of. Recycling is, by and large, a “feel good” thing that many communities do.

        It would be far better to actually design products such that packaging and other “junk” is bio-degradable so that it doesn’t end up in land fills, sitting there forever. The amount of plastic packaging should be drastically reduced. I think that supermarkets and stores like that should go away from providing bags at all. People should have to bring their own (reusable) bags to carry their groceries.

        Anyhow – that’s too long…

  6. Philip DeNolfo

    In RI the power company will tap into your Powerwall during peak overload times (mostly summer afternoons) and pay you for the boost. Typical return is said to be $1000 per PWall per year for at first 5 years. (and RI gives a $2K grant at purchase.)

    Reply

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