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How Many Tesla Powerwalls Do You Need For Your Home?

Tesla powerwall

The Tesla Powerwall is a home battery that stores excess energy generated by solar panels, allowing homeowners to use that energy when the sun isn’t shining or during power outages. It acts as a backup power source, promoting energy resilience and reducing reliance on the grid.

The Powerwall has a storage capacity of 13.5 kilowatt-hours (kWh) per unit and can provide 11.5 kW of continuous power output. This means it can deliver power to essential appliances and lights during outages or periods of low solar production. It also allows you to reap the most out of your solar production, further saving on energy bills. 

The average American homeowner will likely need at least two Powerwalls to meet their energy needs, but it depends on various factors. If you’re wondering, How many Tesla Powerwalls do you need for your home?” we’re here to help. In this article, we’ll explore the key considerations involved:

Want a free quote for a Tesla Powerwall energy storage system?

Contact the experts at Photon Brothers to learn all about the Tesla Powerwall and how it can help you maximize solar power on cloudy days, at night, and during power outages– and save money on energy costs while doing it! We’re proud to have a team of master electricians who are Tesla Certified and have a perfect safety record.

Energy Consumption

Find out how much energy your household consumes on a daily basis so you know what you’ll have a better idea of how much you’ll need to store. The easiest way to do this is to look at your power bills to see your daily or monthly consumption rate. It’s a good idea to look at your power bills over the last year since your energy needs are likely to fluctuate through the changing seasons. Use the highest daily value so you’re not at risk of being without power when you need it.

Solar Panel Output

Next, you need an estimate of your solar panel output. If your solar energy system includes a solar panel monitor, you can easily check your output there. A multimeter will work in a pinch if you don’t have access to historical production, but you’ll need to know how much excess energy is being produced that will apply to charging the Powerwalls. The maximum capacity for a Powerwall is 13.5 kWh, so you will need enough production to cover your needs during the day and charge the Powerwalls for evening use.

For example, let’s say your daily energy consumption is 30 kWh, and your solar panels generate 20 kWh per day. The energy deficit is 10 kWh. If you want backup power for two days, you’ll need 20 kWh of storage. Dividing by the Powerwall capacity (13.5 kWh) results in approximately 1.5 Powerwalls. In this case, you might consider rounding up to 2 Powerwalls for practical purposes.

While the initial investment in multiple Powerwalls may seem substantial, the long-term benefits in terms of energy independence, reduced reliance on the grid, and potential cost savings make them a compelling solution for many homeowners. To learn about tax rebates available, check out our article, Tesla Powerwalls & Tax Credits: What You Need To Know.

Peak Demand Periods

If your solar panels are seeing less sun and output has lowered, your Powerwalls may draw a charge from the grid. They are designed to maximize your savings by pulling this energy during off-peak times. However, you need to know peak demand periods in your area so you can plan to store the power needed and avoid paying peak rates to the power company. This will also help you determine the next factor.

Desired Backup Duration

How much energy do you want to store? Do you just want enough to get you through the evenings after the sun goes down, or are you looking for a backup that can cover you for a few days if the power goes out? Having a number of hours or days in mind can help you calculate the energy needs for that duration, and from there, you can decide how many Powerwalls you would need to cover that timeframe. 

It’s important to note that you may also be limited by your solar panel output if you don’t have enough panels to charge your desired number of Powerwalls. This can be mitigated by charging from the grid, but you will be charged for the energy used for this purpose.

Have more questions about backup power? Check out our article, Backup Battery vs. Generator for Your Home — Which is Better?


For homeowners considering the Tesla Powerwall for energy independence and backup power, the upcoming release of the Tesla Powerwall 3 in early 2024 brings exciting rebate opportunities, especially for those in the Xcel service area. The Powerwall 3, priced at $13,500 before rebates, becomes significantly more affordable with a combination of rebates and incentives: a $5,000 rebate from Xcel, a $500 battery participation incentive, a 30% Federal Investment Tax Credit (ITC) amounting to $4,050, and a $1,000 Colorado State Tax rebate, reducing the total cost to just $2,950 when paired with a solar installation. These rebates not only make the Powerwall 3 an attractive option for sustainable energy storage and backup power but also enhance its affordability, making it a viable option for a broader range of homeowners.

California homeowners residing in fire zones have a unique opportunity to secure their homes against power outages with the help of Tesla Powerwalls, thanks to the Self-Generation Incentive Program (SGIP) rebates. This program, funded by the California Public Utilities Commission (CPUC), offers rebates of up to $13,200 per home battery. Additionally, the 30% Federal Solar Tax Credit can cover any out-of-pocket costs not included in the SGIP rebate.

Grid Independence Goals

Photon Brothers Remote Tesla Powerwall Setup

How important is it to you to be independent from the grid? If your intent is to reduce your grid dependency to get as close to zero as possible, you may need additional Powerwalls to ensure you have enough stored energy to get your household through extended periods with limited sun exposure. If you want to reduce your grid dependence because you like the savings but are okay with grid use when it’s convenient, you could likely get away with less. Figure out your plan, combine the other factors, and you should have a number you can confirm with an expert.

For further reading, check out our article, Can You Go Off-Grid With Solar Panels?

Maximize your energy savings with a Tesla Powerwall system.

Photon Brothers is a certified Tesla installer, and we can integrate your new Powerwall regardless of your existing solar panel setup. Contact us at (720) 370‑3344 (Colorado) or (805) 351‑3371 (California) to discuss your needs. Or, click below to use our online estimator and get a ballpark quote in just seconds!

Photon brothers Matt Raichart

Matt Raichart

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