How Many Powerwalls Do I Need?

Last Updated on June 16, 2022 by

A Powerwall is a battery storage solution from Tesla, that holds energy for you to use later in an emergency. It supports impressive loads of electricity which often makes it a better energy storage solution than other alternatives on the market.

You can use your Powerwall to increase your consumption of solar energy collected, prevent you from spending too much money due to load shifting during off-peak hours, and reach your off-the-grid goals.

Today we are looking at how many Powerwalls you will need to achieve everything that you want to get from them.

Powerwall Calculator

Video – Powerwall calculator for home use

How many powerwalls do you need calculator

There is a calculator that allows you to determine how much you’ll be paying for your Powerwalls as well as how many you will need. Find the calculator here.

All you need to do is add in your grid usage data to the calculator, upload your solar data if you have any available, configure the rate periods, and you’re done. You can now see a simulated number that you could save from using solar for a year.

Now you can change the number of Powerwalls to see how many you need to get your bill down to what you want it to be. It will tell you how much a Powerwall will save you too, so you can understand how valuable they are.

How Many Powerwall Units Do I Need?

The number of powerwalls you need will depend on a number of factors, so we cannot tell you the exact number you will need. Some people will need only one Powerwall and enjoy the benefits, while other people will need three or four to truly feel the effects.

As a very general rule, however, one Powerwall should suffice to cover your emergency circuits, outlets, and lighting. However, if you’re hoping to power larger appliances in your home, you might want to purchase two or three Powerwalls to start with.

Tesla Powerwall Cost

The Tesla Powerwall is not a cheap investment. The newest version, Powerwall 2, has a price range between $4700 and $6700.

The range varies due to the tax incentives that your state offers. Some parts of the USA will offer you money off of your Powerwall due to you not using as much power from the grid.

The installation of your Powerwall will usually then be over $2000. This is a big additional cost considering that you’ll already be paying so much for your Powerwall.

Is It Worth Installing A Tesla Powerwall?

If you are looking for energy independence and to reduce your electricity bill, then it could be worth installing a Tesla Powerwall. It will also help you to minimize your carbon footprint.

The Powerwall allows you to store power for use in emergencies, monitor how much energy you’re using, prevent increasing electricity prices, and protect your home.

If you are living somewhere with lots of power outages or surging energy prices, then it might be worth considering a Powerwall. Your personal situation will determine whether it’s worth installing a Powerwall or not.

How Long Does A Tesla Powerwall Last?

If you experience a power outage and need to rely on your Powerwall to run your emergency appliances and lighting, it should last between 3 and 5 days.

Of course, the amount of appliances and their size you have connected to your Powerwall will affect how long the 13.5kW capacity will last for.

However, if you want to power your entire house like normal, the Powerwall will last for a shorter period of time. Based on the average 28kW energy consumption of a US house, the 13.5kW capacity will last for around 12 hours.

If your solar panels are still replenishing the Powerwall, however, it should be able to last even longer than 5 days.

How Many Years Do Tesla Powerwalls Last?

How Many Powerwalls Do I Need
How do you calculate the number of Powerwalls needed?

The warranty that Tesla offers with its Powerwalls states that the battery will still be 70% effective after 10 years of use.
This means that the Powerwall will lose under 30% storage capacity over these 10 years. If you find that your Powerwall has lost more than 30% capacity within 10 years, it should be covered by the warranty.

How Long Does It Take To Charge A Tesla Powerwall From The Grid?

It is possible to charge your Powerwall from the grid when it is installed without solar.

You can do this by setting your Powerwall to Backup-Only or Time-Based Control mode. This allows your Powerwall to support your house during outages when there isn’t much solar to take advantage of.

If there is nothing plugged into your Powerwall while you’re charging it from the grid, you could see it fully charge within just two hours.

Does Tesla Powerwall Work Off-Grid?

Using your Powerwall in the Self-Powered mode allows you to go energy independent and use less power from the grid.

As long as you have a solar panel collecting energy for you from the sunlight, your Powerwall will continue to work to power your house without any help from the grid.

So, if you want to go off the grid and use only energy that you collected yourself, you can use the Powerwall to do this. Just make sure that you have enough solar panels to replenish the Powerwall so that it doesn’t run out on you.

Going completely off the grid might require you to install more than one Powerwall around your home. Adding more Powerwall capacity to your home ensures that you won’t run out, even on less sunny days.


Overall, it is impossible for us to determine how many Powerwalls you need around your house. One might be enough to power your emergency appliances in an outage, but you will need more than one if you want to go off the grid entirely.

Powerwalls have a capacity of 13.5kW, and the average US house uses 28kW a day. So, without solar replenishing your Powerwall, it will last for 12 hours while powering your entire house.

Bear in mind that you might use more than average and therefore need more than one Powerwall for it to last for 12 hours.

Derek Bruce
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