Tesla Powerwall: Is it the best home battery?
Updated
The Tesla Powerwall has changed the way people talk about solar batteries; from being a conversation about the future to a conversation about the now.
The Powerwall is one of the best solar battery and smart home energy-storage solutions on the market. It has some incredible features and it comes at a reasonable price.
In this article, we take a closer look at the cost, functions, and components of the Tesla Powerwall and what exactly puts it at the top of the market.
On this page:
- Tesla Powerwall cost in 2020
- Rebates and incentives
- Key features
- Total energy capacity
- Usable energy capacity
- Power rating
- Round trip efficiency
- Depth of discharge
- Dimensions
- Weight
- Operating modes
- How long will it last?
- Powerwall vs. net metering
- 4 reasons why Powerwall beats other batteries
- Is Powerwall worth it?
The Tesla Powerwall is a sleek and functional solar battery. Image source: Tesla
How much does the Tesla Powerwall cost in 2020?
As of September 2020, the total cost of installing one Tesla Powerwall battery system is $11,000.
The following table breaks down what goes into this cost:
| Installation component | Cost |
|---|---|
| 1 Powerwall battery | $6,500 |
| Gateway and installation | $4,500 |
| Total cost | $11,000 |
The cost for Tesla’s energy management system, called Gateway ,and the installation decreases as you install more Powerwall battery packs. So, if you install two Powerwall batteries, the Gateway and installation cost will fall to $4,000.
This makes the cost per Powerwall a bit less if you have more than one.
Are there incentives or rebates for installing the Tesla Powerwall?
The cost of a Tesla Powerwall can be a bit intimidating. After all, $11,000 isn’t pocket change. However, there are many incentives out there for solar battery storage.
Federal solar tax credit
One of the most significant incentives for the Powerwall is the federal solar tax credit.
When you install a Tesla Powerwall with a solar panel system, you can get a tax credit equal to 26% of the installation costs. The federal tax credit would drop the installation cost of one Powerwall by $2,860, bringing the total cost down to $8,140.
State and local battery incentives
Some states have solar battery incentives that you can use on top of the federal tax credit.
In California, for example, homeowners can apply to the Self-Generation Incentive Program (SGIP), which would provide a $3,375 rebate for Tesla Powerwall installations. In Vermont, the state’s largest utility company, Green Mountain Power, offers solar battery rebates up to $10,500 as a part of their ‘Bring Your Own Device Program’.
The combination of the federal tax credit and state and local incentives can reduce the cost of installing a Tesla Powerwall by 50%!
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.
| Feature | Specification |
|---|---|
| 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 |
| Weight | 251.3 lbs |
| Operating modes | Solar self-consumption, time-based control, backup |
Tesla Powerwall power capacity
Tesla Powerwall has a storage capacity of 14 kilowatt hours (kWh) of electricity, of which 13.5 kWh is usable. This is about half of the average U.S. home’s daily energy usage.
The Powerwall is one of the highest capacity residential lithium-ion solar batteries on the market.
Tesla Powerwall power rating
The capacity isn’t the only thing that matters. The power output rating of a battery tells you how much power a battery can deliver at a time, or how many appliances it can power.
One Tesla Powerwall will be able to send 5 kW at any time. This power rating is pretty standard for lithium-ion batteries. You can expect one Powerwall to power things such as lights, electrical outlets, and small 120-volt appliances.
If you want to power larger appliances, you may need to install additional Powerwalls.
Tesla Powerwall round trip efficiency
The round trip efficiency of a battery tells you the amount of energy that you can use from your solar battery compared to the amount of energy it took to store that energy. Tesla Powerwall has a round trip efficiency of 90%. This is on the higher end of efficiency ratings for solar batteries on the market.
So for every 10 kWh sent to your Powerwall, 9 kWh will be stored for future use.
Tesla Powerwall depth of discharge
Depth of discharge (DoD) is the percent of the battery’s energy that has been discharged, compared to the overall capacity of the battery. The Tesla Powerwall boasts an impressive 100% DoD, which suggests it should last longer than other batteries on the market.
Basically, having a 100% DoD means that you can use 100% of the energy stored in the battery, without having to worry about causing any damage to the battery.
Tesla Powerwall dimensions and weight
Tesla Powerwall measures 45.3 in x 29.6 in x 5.75 in and weighs in at 251.3 pounds. This is smaller than other solar batteries, especially for having such a high power capacity.
That means a Tesla Powerwall can store more energy in less space.
Powerwalls are able to be ‘stacked’, meaning you can install more than one if you need. Because of their size and sleek design, you can install multiple without having to worry too much about having enough available space.
Tesla Gateway and operating modes
Aside from having some top-notch performance specs, perhaps the most impressive feature of the Powerwall is Tesla’s Gateway system and the battery’s operating modes.
Tesla Gateway is the energy management system for the Powerwall. With Gateway, you can monitor how your battery is operating through the Tesla app. The software also determines how the Powerwall will operate, and controls the safety operations of the battery.
Gateway software is what allows the Powerwall to operate in it’s three different modes: self-powered, time-based control, and backup power mode. These modes can help you rely less on the grid and can even save you more money on your electric bill.
| Operating mode | Functions |
|---|---|
| Self-powered |
|
| Backup-only |
|
| Time-based control |
|
How long does a Tesla Powerwall battery last?
Tesla Powerwall has a warranty that guarantees the battery will operate at at least 70% of its initial capacity after 10 years.
So, 10 years after you install a Powerwall, it should hold at least 9.45 kWh. That’s equal to the initial capacity of some lithium ion batteries! It also means you’ll be able to store more power for longer with a Powerwall.
The lifespan of your Tesla Powerwall also depends on how you use it. If you use your Powerwall to power your home daily, it will probably perform according to the 10-year warranty. However, if you’re only using it as backup power, it could last longer, since you aren’t continuously depleting and recharging the battery.
Do I need a Tesla Powerwall if my utility offers net metering?
Net metering gives you credit for excess power your solar panel system produces and sends to the grid. Essentially, this policy does economically what a solar battery does physically - it provides relief from having to pay for power when your solar panels are not producing. With net metering, the utility acts as your battery storage.
However, many states and utilities don’t offer full retail net metering. This means that you would receive less than the full retail rate of electricity for excess solar production. In these areas, a Tesla Powerwall could allow you to save more on your electric bill. Because the excess energy would be stored, instead of being sent to the utility, it’s like getting the full retail value when you use it later.
Where the Powerewall really comes in handy is if your utility has time-of-use rates. Powerwall is able to learn your energy habits and when your utility charges the most for electricity with it’s time-based control mode. Then, the battery can smartly discharge and recharge based on these electricity rates. This allows you to save even more money than you would with net metering alone.
So, if your utility has net metering, it could still be worth it to get a Powerwall installed if:
- Your utility has a time-of-use billing structure
- Your utility does not offer full retail net metering
- You have access to local battery storage incentives, like SGIP in California
- You live in an area prone to blackouts, where having backup power would be useful
What 4 factors make the Tesla Powerwall stand out as one of the best solar battery solutions on the market?
1. Cost at around $11,000 installed for 13.5 kWhof usable storage. This is a relatively good value given the high cost of solar energy storage. This cost also includes the price of the built-in battery inverter and Gateway management system. It’s still not an amazing return on investment, but better than its peers in terms of getting the most bang for your buck.
2. The three different operating modes ensure that the Powerwall can meet your needs, whether you need backup storage or if you want to save more on your utility bill.
3. Tesla’s mobile app makes it easy to monitor and manage your battery storage system.
4. The 10-year performance warranty, plus high performance specifications like 100% DoD and 13.5 kWh of usable capacity are impressive.
Is the Tesla Powerwall worth it for my home?
Depending on what you want out of a battery storage system, a Tesla Powerwall could be worth it for your home.
If you live somewhere that offers solar battery incentives, installing a Powerwall might not add too much to the cost of a solar system. Also, people with time-of-use electricity rates could actually save more on their electricity bill with a Tesla Powerwall, thanks to it’s time-based control mode.
It’s also important to note that even if you do live somewhere with net metering, you might consider installing a Powerwall for energy security and backup power. With the grid becoming less reliable, whether it be from utility shutoffs to prevent wildfires or frequent long-lasting outages from storm damage, having a secure power source is more important now than ever.
However, if you live in an area with full retail net metering, installing a Tesla Powerwall might not make the most sense economically. Net metering allows your utility to act as a battery, so you don’t have to worry about expensive energy storage. All you have to do is install your solar panels, and start saving.
So, depending on what you’re looking for from an energy storage system, a Tesla Powerwall could be worth it for your home. Powerwall gives you the most for your money, with great specifications, three different operating modes, and reliable energy all for $11,000.
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.