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 how it stacks up to competitors like the LG Chem and sonnenCore solar batteries.
As of January 2021, the total cost of installing one Tesla Powerwall battery system is $12,000.
The following table breaks down what goes into this cost:
|1 Powerwall battery||$7,500|
|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.
You also get a $1,500 discount when you install one Powerwall with Tesla solar panels. The more Powerwalls you install with Tesla solar, the higher that discount gets. You can order a Powerwall directly from Tesla’s website, or from a certified Tesla installer.
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, $12,000, 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.
The spike in Powerwall demand is mostly related to the increase in widespread power outages, like the ones that have recently occurred in California and Texas.
In fact, the demand for Powerwalls is so high that Tesla no longer sells the batteries on their own. In order to get a Tesla Powerwall, you must also get a Tesla solar panel system installed. This could change in the future if demand falls or production ramps up, but for now, Powerwalls must be paired with new solar panel installations.
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, 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:
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.
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.
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 $8,500 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 $950.00 per kWh. You get the best bang for your buck with a Tesla Powerwall.
In our opinion, the Powerwall battery itself is the best home battery for solar storage.
The Powerwall gives you some of the most advanced storage features and technical specs for the lowest possible price. Unfortunately, Tesla has made it much harder for homeowners to get their hands on one.
As we said earlier, you can’t install a Powerwall unless you also install a Tesla solar panel system, which is a huge letdown for a few reasons. First, for homeowners who already have solar panels and want to install a battery, they 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 sub-par customer service that Tesla has been known for, over the lifetime of their solar panels.
You can still get a Powerwall installed through companies like Sunrun, but even with Sunrun you can’t pair a Powerwall with an existing solar installation. If you already have solar installed on your roof, it seems like you’re out of luck.
So, 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 for you, 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.
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