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Tesla Powerwall 2 Review: A Well-Rounded Solar Battery With a Lower Price

Tesla Powerwall 2 Review: A Well-Rounded Solar Battery With a Lower Price


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7.0

Tesla Powerwall 2

Like


  • Unlimited cycle warranty

  • Well-rounded performance and efficiency

  • Compatible with and without solar panels

Don’t like


  • Not as modular as other batteries

  • Glitchy energy management app

  • Bad customer service reputation

If you face frequent power outages, fear higher power bills or want to use your excess solar power, you might want to consider a home battery backup. During your solar battery search, you’ll most likely encounter the Tesla Powerwall 2, Tesla’s second installment of the popular home battery and CNET’s best overall.

Tesla, mostly known for its electric vehicles, has made a name for itself in the solar industry too, since acquiring SolarCity in 2016. Tesla introduced the first Powerwall model in 2015 but didn’t start mass production of the battery until 2017. The current Tesla Powerwall model on the market is the Powerwall 2, which has been around for a few years. Tesla recently announced the Powerwall 3, which will be available to customers sometime in 2024.    

The Powerwall batteries are interesting because they’re just so average, and strangely enough, we mean that in a good way. These batteries are on par with their competition in almost every way. There are a few stand-outs: unlimited-cycle warranty, capacity, stackability, well-rounded specs and some interesting app features are noteworthy. The Powerwall specifications don’t stand out from the battery crowd too much. Nor does it have any particular glaring weaknesses. It does have one of the lowest price points that we’ve seen making it one of the most affordable batteries on the market today. 


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This review focuses on the Tesla Powerwall 2 and is based on specs and information provided by Tesla online. Tesla does not have a media relations department, but they do have a general press email. After emailing this contact, we received no response.

What do I get with a Tesla Powerwall battery?

Tesla Powerwall batteries are some of the most well-rounded lithium-ion batteries available. In our review of solar batteries, the Powerwall 2 model got at least an average rating in just about every category. It’s a good value battery option because it tends to be cheaper than its competitors. 

Tesla has three Powerwall models: the Tesla Powerwall, Tesla Powerwall Plus and the recently announced Tesla Powerwall 3. The Powerwall and Powerwall Plus batteries are similar to one another — the difference is how they interact with your home’s energy system. The Powerwall is compatible with new and existing solar panel systems. It can also work as a stand-alone home battery without solar panels. On the other hand, the Powerwall Plus battery is integrated with a Tesla Solar Inverter and must be installed with solar panels. Both Tesla batteries can be installed with other brands of solar panels. You don’t need Tesla solar panels to install a Powerwall.

Tesla has yet to release a spec sheet for its Powerwall 3 model, so we don’t know all the details yet. We do know that the Powerwall 3 has the same storage capacity as the other Powerwall batteries, and it’s twice as powerful too.

Tesla Powerwall Tesla Powerwall

Tesla

Like:

  • Large storage capacity
  • Compatible with and without solar panels
  • Well-rounded specs 
  • Excellent warranty

Don’t like:

tesla-powerwall-battery-backup tesla-powerwall-battery-backup

Tesla

Like:

  • Large storage capacity
  • Integrated solar inverter
  • Higher backup (off-grid) power output 
  • Excellent warranty

Don’t like:

  • Lower on-grid power output (same as Powerwall 2)
  • Must be installed with solar panels

A Tesla Powerwall 3 battery in a garage. A Tesla Powerwall 3 battery in a garage.

Tesla

Like:

  • Large storage capacity
  • High power output

Don’t like:

  • Can’t be installed with Powerwall 2 or Powerwall Plus batteries
  • Limited warranty and spec details currently

Tesla Powerwall battery specs

Category Tesla Powerwall Tesla Powerwall Plus Tesla Powerwall 3
Usable capacity 13.5 kWh 13.5 kWh 13.5 kWh
How many can I stack? Up to 10 units Up to 10 units 40.5 kWh max addition per unit
Round-trip efficiency 90% 90% NA
Depth of discharge 100% 100% NA
Continuous power output (on-grid) 5 kW 5 kW 11.5 kW
Continuous power output (off-grid) NA 7 kW – 9.6 kW NA
Battery type Lithium-ion Lithium-ion Lithium-ion
AC- or DC-coupled? AC DC NA
Price $9,000 – $13,000 NA NA

Capacity and modularity

All three Tesla batteries have a 13.5 kilowatt-hour energy capacity, a decent size for a home battery backup. If you have a larger home (or plan on going off-grid), you’ll likely need multiple Powerwalls. One Tesla Powerwall battery is ideal for partial home backup, while whole-home backup will likely require two or more Powerwalls. You can install up to 10 Powerwall 2 units or Powerwall Plus units for a total of 135 kWh of energy storage. Both battery models can be mixed. The Powerwall 3 is not compatible with the Powerwall 2 and Powerwall Plus models. 

Tesla Powerwall batteries are not as modular as other batteries on the market, making size upgrades difficult (and expensive). If you find yourself needing a capacity upgrade, you’ll have to buy another 13.5 kWh battery. 

Performance and efficiency

The Powerwall 2 is about average efficiency for the batteries we examined. The Powerwall 2’s round-trip efficiency is 90%, meaning 10% of the electricity gets lost on its way to the battery for storage. A round-trip efficiency of 90% (or higher) is standard for lithium-ion batteries. The Powerwall Plus also has a round-trip efficiency of 90%.

The Tesla Powerwall 2’s depth of discharge (how much of the battery you can use at once without damaging it) is the best it can be: 100%. Just because you can drain the majority of your battery all at once doesn’t mean you should. One of the main factors affecting a battery’s lifespan is the number of cycles it goes through. A battery cycle is the process of discharging (emptying) your battery and then recharging it. In other words, the fewer times you fully cycle your battery, the better. The Powerwall Plus also has a 100% depth of discharge rating.

What about power output? It’s fine. One Powerwall 2 can output a peak of 7 kilowatts, with a continuous power output of 5 kW. A battery’s peak power output is the amount of power the battery can put out all at once without damaging anything. Peak power output is typically used when activating large loads or appliances, such as when your AC or heat kicks on. Continuous power output is the amount of power the battery can put out at all times. The more Powerwalls you install, the higher the power output. 

The Tesla Powerwall 2 and Powerwall Plus have the same on-grid power output capabilities, but the Powerwall Plus has far better backup power output capabilities, with a peak power output rating of 22 kW in full sun or 10 kW with no sun and a continuous power output rating of 9.6 kW in full sun or 7 kW with no sun. The Tesla Powerwall 2 can also be installed in a system with a backup generator, but it will need to be connected with an external automatic or manual transfer switch.

Read more: Just looking for an emergency backup? Check out portable solar panels and solar generators.  

Customer service

Tesla’s online customer service reputation is not the best, and it seems easier to find bad customer service reviews than good ones. Tesla Solar is not Better Business Bureau accredited, but anecdotal evidence suggests poor customer service and some customers even regretting their purchases. There are frequent complaints about rude customer service or sales representatives, as well as Tesla not following through when it comes to communicating with their customers. 

Warranty 

Tesla’s warranty for the Powerwall 2 and Powerwall Plus batteries stands out among competitors. Here’s what it includes:

  • 10 years
  • Unlimited cycles
  • 70% end-of-warranty capacity guarantee 

A 10-year warranty is the industry standard for solar batteries, but few come with unlimited cycles. The typical battery warranty covers 4,000 to 6,000 cycles, making Tesla’s unlimited-cycle warranty more competitive. The number of times you cycle your battery (drain and recharge it) affects its lifespan, which is why many manufacturers will include a cycle or throughput clause in their warranty. 

The Powerwall’s warranty also comes with a 70% end-of-warranty capacity guarantee. Batteries lose capacity and their ability to hold a charge over time, so some manufacturers will include an end-of-warranty capacity guarantee. This is the manufacturer’s guarantee that your battery will be able to store a specific percentage amount of energy by the time your warranty period is up. Tesla guarantees the Powerwall will retain at least 70% of its original capacity by the time your warranty ends.

0x0-powerwall-08 0x0-powerwall-08

Tesla

Tesla app

Using the Tesla app, you’ll be able to view and monitor your home’s energy usage, as well as analyze and compare data about your home’s past and current energy production. Powerwall can also be customized to help support your energy goals by using the different control mode settings through the app. These settings essentially change how your battery charges and discharges. Keep in mind that some features and settings are only available when paired with solar panels. 

You can also set a designated percentage of your Powerwall’s capacity aside to be reserved for backup power in the event of grid outages. Tesla recommends setting a backup reserve of 20% when using the backup reserve setting, but you can set it to whatever you like. 

The Tesla app is not without its flaws. Online reviews show complaints about frequent glitches and the unreliability of the app, with some people saying it only seems to work half the time they use it.

Tesla Powerwall 2 vs. Tesla Powerwall Plus

There isn’t much of a difference between the Powerwall 2 and Powerwall Plus. The Tesla Powerwall 2 is just a battery and can be installed with or without solar panels. The Tesla Powerwall Plus is a regular Tesla Powerwall 2 battery that has been integrated with a Tesla Solar Inverter. The Powerwall Plus is designed specifically for solar installations, while the regular Powerwall 2 model is compatible with or without solar panels. 

Both batteries have the same capacity (13.5 kWh). The Powerwall Plus has a much higher backup power output rating, making it a better option if you are installing a new system and have plans to go completely or partially off the power grid. Most homes will likely need more than one Tesla battery (of any model) to live completely off-grid. Both Tesla batteries are interchangeable, meaning you can install a mix of up to 10 Powerwall 2 and Powerwall Plus batteries. 

What we know about the Tesla Powerwall 3

Tesla debuted the Powerwall 3 at this year’s RE+, a renewable energy trade show in Las Vegas. During the week of the show, the company updated its website with some details about the Powerwall 3 but hasn’t released a spec sheet yet. Representatives at RE+ also declined to speak with CNET about it. We might not have all the details as of right now, but here’s what we do know.

The Tesla Powerwall 3 has an energy storage capacity of 13.5 kWh, the same as the other Powerwall batteries. The Powerwall 3 is also over twice as powerful as the other Powerwall batteries, with a continuous power output of 11.5 kW. So yeah, it’s kind of a powerhouse. 

Like the Tesla Powerwall Plus, the Powerwall 3 has an integrated solar inverter, meaning it can be DC-coupled for higher efficiency. It’s not compatible with other solar inverters. The Tesla Powerwall 3 can’t be installed with other Powerwall models either. So if you already have a Tesla Powerwall 2 or Powerwall Plus battery, you won’t be able to add on the Tesla Powerwall 3.  

The Powerwall 3 comes with a 10-year warranty, but we aren’t yet sure if it will have the same unlimited-cycle warranty as the other Powerwall batteries. Tesla’s new battery is set to be released to the public sometime in 2024. Pricing information is unknown.

The Tesla Powerwall 3 on the show floor at RE+ The Tesla Powerwall 3 on the show floor at RE+

Tesla unveiled its new Powerwall 3 battery on the show floor at the 2023 RE+ renewable energy trade show in Las Vegas.

Sarah Drolet/CNET

How much does the Tesla Powerwall cost?

Home battery systems are not cheap. The Tesla Powerwall 2 costs between $9,000 to $13,000. Pricing depends on your location and other installation and labor costs. The Powerwall 2 tends to be cheaper than similar competing batteries. When it comes to batteries, you can generally expect to pay between $1,000 and $2,000 per kilowatt-hour of energy storage. 

To get the most accurate pricing information, talk to a Tesla-certified installer in your area, and get multiple quotes to get the best price possible. Gathering a mix of quotes from national and local installers is the way to go. 

Is the Tesla Powerwall my best choice?

The Powerwall 2 is a well-rounded battery in its capacity, performance and efficiency. Is it a decent battery? Yes. Is it your best choice? It depends. The best battery for your home is one that fits your household’s energy needs and what you are looking to accomplish with a battery installation. Most installers offer more than one brand of battery, so explore other battery options from installers in your area if you can. Try to get multiple quotes to get the best price possible. Here’s a look at how the Tesla Powerall 2 stacks up against other popular solar batteries.

The Tesla Powerwall 2 vs. other batteries

Category Tesla Powerwall 2 Generac Pwrcell LGES 16H Prime Enphase IQ Battery 10/10T SunPower SunVault (single unit) Sonnen Core Plus
Usable Capacity 13.5kWh 9 kWh – 18 kWh (Installed in increments of 3 kWh) 16kWh 10.08kWh 13kWh – 19.5kWh 10kWh or 20kWh
How many can I stack? Up to 10 units Up to two battery cabinets (units) Up to two units NA Up to one additional unit (double unit) Up to three 10kWh or 20kWh units
Round-trip efficiency 90% 96.50% 90% 89% 86% 85.80%
Depth of discharge 100% 84% 100% 98% 92% 100%
Continuous power output (on-grid) 5kW 3.4 kW – 7.6 kW 7kW 3.84kW 6.8kW 4.8kW – 14.4kW
AC- or DC-coupled? AC DC AC AC AC AC
Price $9,000 – $13,000 $10,000 – $20,000 $7,000 – $11,000 $8,000 – $10,000 $16,000 – $20,000 (includes installation) Starting at $10,300

How we evaluated the best solar batteries

Not every battery is right for every home. It’s difficult to pinpoint exactly which solar battery is the “best” battery for your home without doing an on-site inspection. We’re unable to do hands-on testing with solar batteries because of the complexity of solar panel systems, but there are ways to evaluate and compare these batteries. Here’s how we evaluate solar batteries.

First, we created categories that would be used to evaluate the battery’s efficiency, performance, capacity and value. We also weighted each category. The weight of each category reflects the importance we felt was relevant to the average person. Here are the categories we considered and their weights:

  • Battery modularity (stackability): 20%
  • Warranty: 20%
  • Round-trip efficiency: 15%
  • Depth of discharge: 10%
  • Power output: 10%
  • Price: 10%
  • Customer reviews: 10%
  • Battery capacity: 5%

We looked at more than 15 of the most common batteries on the market and collected the data for each category to compare the numbers. Each category (for every battery) was then given a tier-style rating (from 1 to 5) to see which aspects of each battery were above average (among those on our list), average or below average. 

Frequently asked questions

Can I live off-grid with the Tesla Powerwall battery?

Yes, but you would likely need multiple Powerwalls to go completely off the power grid. If you’re installing a new solar system and have plans to go off-grid, consider installing the Powerwall Plus, which has a higher backup power output and was solely designed for solar purposes. You will likely still need multiple Powerwall Plus batteries to truly go off-grid.

Is the Tesla Powerwall eligible for the federal solar tax credit?

How do I install a Tesla Powerwall?

You can order a Powerwall online through Tesla or find an installer in your area that installs Powerwalls. If you order your Powerwall online and are located at a Tesla-serviceable address, Tesla will bring the Powerwall to your home and install it for you. If you are not at a Tesla-serviceable address, your installation will go through a Tesla-certified installer in your area.

What is the energy storage capacity of the Tesla Powerwall?

The Tesla Powerwall has 13.5 kWh of usable capacity. This is a decent size for a singular battery, but if you’re looking for whole-home backup, you’ll need multiple Powerwalls. You can install up to 10 Powerwalls for a total of 135 kWh. The Powerwall and Powerwall Plus batteries can be installed together. 

When will the Tesla Powerwall 3 be released?

Tesla says the Powerwall 3 will be available sometime in 2024. Pricing information is still unknown.





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