Tesla Powerwall: Is it the best solar battery?
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Solar storage was once a conversation about the distant future, but Elon Musk's announcement of the Tesla Powerwall battery system changed it to a conversation about the now.
The Powerwall is, without a doubt, a great home energy storage solution. It has some incredible features, and it comes at a reasonable price. But is it the best solar home battery to pair with your solar panels?
In this article, we take a closer look at the cost, functions, and components of the Tesla Powerwall battery, and the new Powerwall+ version, and how it stacks up to competitors like the LG Chem and sonnenCore solar batteries.
In early April 2021, Tesla stopped selling Powerwalls for individual sale. Instead, anyone who wanted a Tesla Powerwall would have to also install a brand new Tesla solar panel or solar roof system. That means no retrofits for existing solar systems, which is definitely a bummer.
Tesla then took it a step further later in April, when Tesla CEO Elon Musk tweeted that all Tesla solar panel and solar roof systems would be bundled with a Powerwall. So now, you have to purchase a Powerwall when you purchase solar panels through Tesla.
That wasn’t Musk’s only announcement. In Tesla’s Q1 2021 call, he revealed that Tesla has been manufacturing the “Powerwall +”, which has a higher peak power capability than previous models and comes with an integrated inverter, giving it a slightly different look than before.
Overall though, the Tesla Powerwall+ has almost all the same features as the Powerwall.
As of June 2021, the total cost of installing one Tesla Powerwall+ battery system is $10,500.
The more Powerwalls you install, the cheaper they become. This is because the installation labor costs are spread out over the two batteries as opposed to just one. And remember, Tesla no longer sells their Powerwalls individually, so the total amount you'll have to pay will be for the price of a Powerwall and the price of a new solar panel system.
Tesla no longer provides a breakdown of the price of the Powerwall, instead they only offer a total installation price.
The following table breaks down what goes into the cost of installing Powerwalls:
|Number of Powerwalls||Installation cost|
Despite Tesla claiming that the Tesla Powerwall cost would drop by half in the next three years, we’ve seen the price of the Powerwall increase twice, to its current price of $10,500, since that announcement in September 2020. Luckily, there are battery incentives available in some areas to help lower the cost of installation.
Not only can you take advantage of the 26% federal tax credit, some states and utilities offer additional rebates and incentives, as well. In some cases, rebates like California’s SGIP incentive and Green Mountain Power’s Bring Your Own Device Program in Vermont, can cover almost 90% of the total cost of installing a Powerwall.
Tesla Powerwalls have a substantial wait time because the demand for them is so high and their production simply can’t keep up. Some people have reported that they have to wait a full year before receiving the Powerwall they ordered.
It seems as though customers who order their Powerwall systems directly from Tesla have substantially shorter wait times - usually just a few months. However, those who have ordered Powerwalls through Tesla installation partners have waited almost a year to get their Powerwall. It seems Tesla has prioritized filling their direct orders first, and are leaving their installation partners out to dry.
There has been a spike in Powerwall demand, mostly related to the increase in widespread power outages, like the ones that have recently occurred in California and Texas.
So, if you’re looking for a battery to add to your already existing solar system, or you don’t want to wait a year or more to get a solar battery installed, you’ll need to find a Powerwall alternative.
What exactly do you get when you pay for a Tesla Powerwall? The answer is: a lot.
The Tesla Powerwall has some of the best technical specifications in the solar battery game, as well as impressive smart monitoring and management.
|Feature||Tesla Powerwall specification||Tesla Powerwall+ specification|
|Total energy capacity||14 kWh||14 kWh|
|Usable energy capacity||13.5 kWh||13.5 kWh|
|Continuous power rating||5 kW continuous||On grid: 7.6 kW full sun/5.8 kW no sun, Off-grid: 9.6 kW full sun/7 kW no sun|
|Peak power rating||7 kW||Off-grid: 22 kW full sun/10 kW no sun|
|Round trip efficiency||90%||90%|
|Depth of discharge||100%||100%|
|Dimensions||45.3 in x 29.6 in x 5.75 in||62.8 in x 29.7 in x 6.3 in|
|Weight||251.3 lbs||343.9 lbs|
|Operating modes||Solar Self-Consumption, Time-Based Control, Backup Power||Solar Self-Consumption, Time-Based Control, Backup Power|
With the ability to hold 13.5 kilowatt hours (kWh) of electricity, the Powerwall has one of the highest usable capacity ratings of residential solar batteries on the market. That’s enough energy to cover about half of the average U.S. home’s daily energy usage.
The Tesla Powerwall+ comes integrated with the Tesla inverter and system controller, which allows for a quicker and more condensed installation. Aside from the new installation setup, the main difference between the Powerwall and the Powerwall+ is the power output, which now is slightly higher than industry standards. In full sun conditions, the Powerwall+ can provide 7.6 kW of continuous power and 5.8 kW with no sun when connected to the grid. This means the battery can power things such as lights, electrical outlets, and small 120-volt appliances.
For off-grid applications, however, the Powerwall+ can release more power - between 7 kW and 9.6 kW - depending on the conditions. So, when your Powerwall is not connected to the grid, like during a power outage, it has the ability to power a few more appliances in your home.
The upgraded Powerwall also has a much higher peak power capacity when operating off-grid, ranging from 10 kW to a whopping 22 kW if the sun is shining. The peak power capacity is the absolute maximum amount of power a battery can supply for a very short period of time. Usually, the battery will reach peak power capacity when multiple appliances are being turned on at once, like when the power goes out and comes back on.
What really makes the Powerwall stand out is its three operating modes:
These modes allow you to choose how and when you release and store energy in your battery. For instance, in Solar Self-Consumption Mode, you can power your home with renewable energy by storing solar power for use later, or the Powerall can just serve as an emergency battery backup in case of a blackout.
The Powerwall’s warranty is pretty standard for lithium ion batteries - the battery will operate at 70% of its original capacity after 10 years. Which operating mode you choose will impact how long your Powerwall battery will last. The specifics of how your usage impacts the battery life is outlined in Tesla’s warranty.
How exactly do these batteries stack up to the Powerwall? Let’s take a closer look.
|Battery chemistry||Lithium nickel manganese cobalt (NMC)||NMC||Lithium iron phosphate (LFP)|
|Usable energy capacity||13.5 kWh||9.3 kWh||10 kWh|
|Power rating||On grid: 7.6 kW full sun/5.8 kW no sun, Off-grid: 9.6 kW full sun/7 kW no sun||5.0 kW continuous / 7.0 kW peak||4.8 kW continuous / 8.6 kW peak|
|Operating modes||Solar Self-Consumption, Time of Use, Backup Power||Solar Self-Consumption, Backup Power||Solar Self-Consumption, Time of Use, Backup Power|
|Warranty||10 years or 37.8 MWh throughput||10 years or 22.4 MWh throughput||10 years or 58 MWh throughput|
All of these batteries will be able to do the bare minimum of storing solar energy for use later or in case of a power outage.
In Solar Self-Consumption Mode, your solar system will send the extra energy it produces during the day to the battery. That stored energy will be used later to power your home when your solar panels are no longer producing energy.
In Backup Power Mode, the battery will be charged, either by solar or from the grid, and it will only be used in the event of a grid outage. The batteries are able to detect a blackout and switch over to battery power in real time.
Where the Tesla Powerwall and the sonnenCore battery pull ahead is with their Time-of-Use functionality which allows the batteries to change how they are charged based on the price your utility is charging for electricity with Time-of-Use rates.
For example, when the price for electricity is low, your Powerwall will take more power from your solar panels and have your home draw cheap energy from the grid. Then, when the price for power increases at a peak time, you will draw power from your Powerwall, instead of expensive electricity from the grid.
This allows you to save more on your electricity bills.
In terms of power ratings, the Powerwall+ can deliver more power than the LG Chem and the sonnenCore. Combined with the higher capacity rating of the Powerwall+, not only can it power more things in your home, it can power them for longer.
Although the Powerwall+’s peak power capabilities pack quite the punch when operating off the grid, there’s nothing on the spec sheet to tell us what the peak power capacity is while it is connected to the grid. We can assume that it’s higher than 7.6 kW, which is the maximum amount of continuous power that the battery can deliver, but we don’t know if it’s high enough to beat the sonnenCore’s peak power capacity of 8.6 kW.
Overall, the Powerwall+ comes out on top because it can power the most appliances for the longest period of time, and its off-grid capabilities are quite impressive. We just wish there was some indication of its peak power ability while connected to the grid.
All of these batteries are able to last 10 years with regular use. But when you look at the fine print, you’ll find that the sonnenCore has a better warranty than the Tesla Powerwall and the LG Chem.
The sonnenCore will operate at 70% of its original capacity after it releases 58 megawatt hours (MWh) of electricity, or after 10 years - whichever comes first. The Powerwall on the other hand will operate at 70% after releasing 37.8 MWh of electricity.
Because the sonnenCore battery is a lithium iron phosphate battery, it is able to last longer than lithium nickel manganese cobalt batteries like the Powerwall. Plus, because the sonnenCore doesn’t contain cobalt, it’s less likely to catch fire than the Tesla Powerwall, and it’s easier to recycle.
The Tesla Powerwall is the best battery in terms of price, especially for all of the features you get with it. The Tesla Powerwall and Gateway management program cost $8,500 before installation, which comes out to about $629.63 per kWh of storage capacity.
The LG Chem costs about $735.68 per kWh, which means you’d be paying more per kWh for a battery with fewer capabilities than the Powerwall.
The sonnenCore is the most expensive at $950 per kWh, but its lithium iron phosphate chemistry provides added safety and allows it to last longer than its competitors.
But, in terms of which gives you the most bang for your buck - it’s the Tesla Powerwall. Too bad you have to purchase an entire solar system with it.
In our opinion, the Powerwall battery itself is the best home battery for solar storage because it gives you great advanced features and technical specs for the lowest price possible.
But, is the Powerwall worth it? To be honest, not really.
Unfortunately, Tesla’s decision to only sell Powerwalls with new solar panel installations makes it much harder for homeowners to get their hands on one, which is a huge letdown for a few reasons.
First, homeowners who already have solar panels and want to install a battery can no longer get a Powerwall.
Second, when it comes to solar installations, Tesla is notorious for having poor after-sales service. So now, if homeowners want a Tesla Powerwall, they run the risk of dealing with the subpar customer service that Tesla has been known for. And that’s not just when you’re getting the system installed, it’s a problem you’ll have to deal with over the lifetime of the solar panels - a whole 25 years!
Plus, Tesla recently increased the prices of solar roof systems for customers who already signed contracts, making it even more difficult for consumers to trust them. Who’s to say they won’t increase your prices after you sign a contract?
You can still get a Powerwall installed through companies like Sunrun, but even then you can’t pair a Powerwall with an existing solar installation. Besides, with Tesla filling their own orders before honoring projects their installation partners have already signed contracts for, there’s no telling when you’ll get a Powerwall from someone other than Tesla.
So if you already have solar installed on your roof, we’re sorry to say it seems like you’re out of luck.
With all that being said, if you don’t already have solar, are willing to risk getting poor customer service over the 25 years that you have Tesla panels on your roof, plus are okay with potentially month or year-long wait times to get a battery installed, then a Tesla Powerwall is right for you.
If that’s not going to cut it, you can always contact local solar installers and find out what solar batteries they recommend, or if they have Powerwalls in stock to install. The easiest way to find installers that can help you pair a solar installation with storage at the best price in your area is by using our solar calculator below.
Some solar installers use inflated estimates of utility price growth to make it seem like savings will be higher than they likely will. It’s time to stop.