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 Tesla Powerwall battery system changed it to a conversation about the now. There have been several versions of the Tesla Powerwall, including its current offering, the “Powerwall+”.
The Powerwall is, without a doubt, a great home energy storage solution. It has some incredible features and comes at a reasonable price. But is it the best solar home battery to pair with your solar panels? The answer might surprise you.
As of July 2021, the total cost of installing one Tesla Powerwall+ battery system is $10,500.
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, eventually reaching its current price since that announcement in September 2020.
Not only that, 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 may also require you to upgrade your electrical panel before you install a Powerwall, which can add another $2,500 to your installation (a cost that Tesla doesn’t mention at all in their initial online price estimates).
Yes, the Tesla Powerwall does qualify for the battery storage incentives available in the U.S.
The biggest incentive is the federal solar tax credit, which will reduce the cost of a Powerwall installation by 26% as long as it is paired with solar panels (which is inevitable, as Tesla requires you to install Tesla solar panels or their solar roof with the purchase of a Powerwall).
Aside from the federal tax credit, some states and utilities offer additional rebates and incentives. In some cases, these 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.
The Tesla Powerwall has some great specifications, as well as some of the most impressive smart monitoring and management in the solar battery game.
|Feature||Tesla Powerwall+ specification|
|Usable energy capacity||13.5 kWh|
|Continuous 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|
|Peak power rating||Off-grid: 22 kW full sun/10 kW no sun|
|Round trip efficiency||90%|
|Depth of discharge||100%|
|Dimensions||62.8 in x 29.7 in x 6.3 in|
|Operating modes||Solar Self-Consumption, Time-Based Control, Backup Power|
The Powerwall’s lifespan is pretty standard for lithium ion batteries - it will operate at 70% of its original capacity after 10 years. The operating mode you choose will impact how long your Powerwall battery will last.
The specifics of how your usage impacts the battery life are outlined in Tesla’s warranty.
A battery’s capacity tells you how much electricity it can store. The higher the capacity, the longer the battery can power your home. With the ability to hold 13.5 kilowatt-hours (kWh) of electricity, the Powerwall can store enough energy to cover about half of the average American home’s daily energy usage.
With one charge, a Powerwall can likely run the essentials in your home, like your refrigerator, WiFi, some outlets, and a few lights for about 24 hours.
The release of the Powerwall+ brought one major change: a higher power rating. The continuous power rating of a battery tells you what and how many appliances it can run.
Powerwall batteries that are connected to the grid can now deliver 7.6 kW of continuous power when the sun is shining, and 5.6 kW with no sun. This means one Powerwall can run lights, electrical outlets, and 120-volt appliances like your fridge. If you want to run high-powered appliances, such as an air conditioner, you’ll need additional Powerwalls.
What’s unique about the Powerwall is that the battery is able to release more power when it’s operating off-grid, ranging between 7 kW and 9.6 kW of output depending on weather conditions. So, when the Powerwall is not connected to the grid, like during a power outage, it has the ability to run a few more appliances in your home.
Aside from the continuous power rating, batteries also have a peak power rating, which is the maximum amount of power a battery can deliver in a very short time (usually about 10 seconds). Basically, the peak power rating measures the battery's ability to withstand brief power surges, like when appliances are drawing more electricity to power on.
There is no peak power rating for the Powerwall when it is connected to the grid, but when operating off-grid the peak power ranges from 10 kW to a whopping 22 kW if the sun is shining. These numbers are substantially higher than the industry average for peak power rating, which is usually around 7 kW of output.
The Powerwall also has three standard operating modes:
These modes allow you to choose how and when you release and store energy in your battery. In Solar Self-Consumption Mode, you can power your home with renewable energy even when the sun isn’t shining by storing excess solar power for use later.
With Backup Power mode, you can select to have your Powerwall simply serve as an emergency battery backup in case of a blackout.
Time-Based Control mode comes in handy when your utility uses Time-of-Use (TOU) rates, which is when the utility charges different electric rates depending on the time of day. When your Powerwall operates in Time-Based Control mode, it will automatically charge the battery when electricity is cheapest, and will discharge when electricity prices are most expensive, allowing you to save money on your utility bill.
The Tesla Powerwall is an AC-coupled battery, meaning the battery comes with its own integrated storage inverter (which is just an inverter that’s built into a battery). The main advantage of AC-coupled batteries is that they’re easy to connect to existing solar panel systems. Plus, if something goes wrong with your solar inverter, your battery will keep working, and vice versa.
However, AC-coupled battery systems are a little less efficient than DC-batteries, and having additional hardware means there are more parts that can fail.
You can read more about the differences between AC and DC-coupled batteries in our comparison guide.
Tesla Powerwalls have a substantial wait time because the demand for solar batteries is so high as more homeowners want access to reliable backup power. Tesla’s production simply can’t keep up. In fact, it was recently revealed that Tesla has 80,000 Powerwall orders that have yet to be fulfilled.
You can purchase a Powerwall from Tesla directly with the purchase of a solar roof for solar panels, or from a Tesla partner installer. However, customers who order their Powerwall systems directly from Tesla have shorter wait times - usually a few months. Those who are getting a Powerwall through Tesla installation partners have waited almost a year to get their battery installed. It seems as though Tesla has prioritized filling their direct orders first, and are leaving their installation partners out to dry.
So, if you’re looking for a battery to add to your already existing solar system and you don’t want to wait a year or more to get a solar battery installed, you’ll need to find a Powerwall alternative.
Tesla Powerwalls can operate without solar panels and just collect power from the grid to be used as backup power during a grid outage. However, Tesla no longer sells Powerwalls individually, so in order to get a Powerwall directly from Tesla you must also order a Tesla solar panel or solar roof system.
If you want to buy a Powerwall without also paying for and installing a full solar power system, you won’t be able to get the battery directly from Tesla. Instead, you’d have to purchase a Powerwall for individual sale through a certified Tesla Powerwall installer.
But as we said earlier, using a Tesla partner tends to mean longer wait times, and it can be hard to find an installer who will install a battery on its own without solar, as it’s not as profitable for the installer. So it can be done, it could just be difficult to locate one - and you’d have to be prepared for a longer wait time.
Otherwise, to get a Powerwall straight from Tesla in a timely fashion, you need to order a solar system through the Tesla website.
In our opinion, the Powerwall is a great battery. It has advanced features and impressive technical specs for a decent price.
But is the Powerwall worth it? To be honest, not really. The battery that we put at the top of our list is the LG Chem Prime because of its high power capacity, operating modes, and low price.
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 right from Tesla, and instead have to search for a certified installer willing to sell a Powerwall to them. Plus, they then might have to deal with a substantial wait time.
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!
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. Tesla has already altered signed contracts in the past for their solar roof, and there’s no guarantee it won’t happen with their Powerwalls.
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, or are okay with potentially months 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.
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