Tesla Powerwall: Is it the best solar battery?
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 how it stacks up to competitors like the LG Chem and sonnenCore solar batteries.
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How much does the Tesla Powerwall cost in 2021?
As of January 2021, the total cost of installing one Tesla Powerwall battery system is $11,500.
The following table breaks down what goes into this cost:
|1 Powerwall battery||$7,000|
|Gateway and installation||$4,500|
The cost for Tesla’s energy management system, Gateway, as well as the installation, decreases as you install more battery packs. That means if you install two Tesla batteries, the Gateway and installation costs will fall to $4,000.
The cost of installing a Powerwall can be a bit intimidating. After all, $11,500 isn’t pocket change. But, there are battery incentives available 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.
Key features of the Tesla Powerwall
So, 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, plus the Gateway management system, which allows for smart monitoring and management.
|Total energy capacity||14 kWh|
|Usable energy capacity||13.5 kWh|
|Power rating||7 kW peak / 5 kW continuous|
|Round trip efficiency||90%|
|Depth of discharge||100%|
|Dimensions||45.3 in x 29.6 in x 5.75 in|
|Operating modes||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 has a built-in inverter and a fairly standard power output of 5 kW, so it can power things such as lights, electrical outlets, and small 120-volt appliances. Anything larger than that will require additional Powerwalls to run.
What really makes the Powerwall stand out is its three operating modes:
- Solar Self-Consumption
- Time-Based Control
- Backup Power
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 do other solar batteries compare to the Powerwall?
There are many solar batteries on the market to choose from. Some of Tesla’s top competitors include the LG Chem RESU and the new sonnenCore battery.
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||5.0 kW continuous / 7.0 kW peak||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 mMode, 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.
Capacity and power rating
In terms of power ratings, the Powerwall and LG Chem are the same, so you’ll be able to power the same appliances with both of these batteries. But, the Tesla Powerwall will be able to power appliances for longer periods of time because it has a larger capacity than the LG Chem.
The sonnenCore has a slightly lower continuous power of 4.8 kW, and a slightly higher peak power of 8.6 kW. This means it will power fewer appliances than the Powerwall, but it is better-equipped to handle short spikes in power consumption.
Overall, the Powerwall comes out on top because it can power the most appliances for the longest period of time.
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 $8,000 before installation, which comes out to about $592.59 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 $950.00 per kWh. You get the best bang for your buck with a Tesla Powerwall.
Is the Tesla Powerwall worth it?
If you’re looking for energy storage to pair with your solar panels, then yes, the Tesla Powerwall is worth it. In our opinion, the Powerwall is the best home battery for solar storage. With the Powerwall, you’re getting some of the most advanced storage features and technical specs for the lowest possible price.
But you should keep in mind that you might have a substantial wait before a Powerwall is installed in your home. Tesla Energy is notorious for having slow-moving customer service, and even though you can get Powerwalls installed by companies like Sunrun, it can still take time, depending on how many batteries the installer has in stock.
This is especially an issue in places like California, which has substantial solar battery rebates and frequent blackouts, which have led to skyrocketing demand for Powerwalls. However, this issue tends to be specific to your region.
The best way to know how long it could be until you get a Powerwall is to contact local installers and Tesla themselves to find out how long the waitlist is and if they are performing installations in or near your area.
Overall, the Powerwall is the best battery you can pair with your solar system, as long as it’s available in your area. Use our solar panel calculator below to find solar companies near you that can help you pair a solar installation with battery storage at the best price possible.
- The Tesla Powerwall costs $11,500. With the federal solar tax credit, a Tesla Powerwall costs about $8,500.
- The Tesla Powerwall has some impressive specs, including 13.5 kWh of electricity storage, a continuous output of 5 kW, and three operating modes: Solar Self-Consumption, Backup only, and Time-based Control Mode.
- While other batteries like the LG Chem and sonnenCore have great specs, and in some cases better specs than the Powerwall, Tesla’s battery offers the most features at the lowest price.
- Keep in mind, Tesla Energy is known for slow customer service, and the availability of Powerwalls varies widely between locations.
- If Tesla Powerwalls are available for installation in your area, they are the solar battery that will deliver the most bang for your buck. Use our solar calculator to find wait times for Powerwall installations near you.
Author: Andrew Sendy | Home Solar Journalist
Andy is deeply concerned about climate change but is also concerned about cost of living pressures on American families. He advocates for solar energy and solar battery storage only to the extent that they make financial sense for homeowners. He is not affiliated with any particular solar company in the United States.