Can You Charge a Tesla Powerwall with a Generator?

Can You Charge a Tesla Powerwall with a Generator?

When the power goes out in your neighborhood, having solar can be a lifesaver. Unfortunately, due to the inherent drawbacks of relying upon the sun for energy, your Powerwall can sometimes lack a sufficient charge to power your home. When this rare occasion comes, the lack of juice in them may make you wish to charge your Powerwall batteries with a generator.

Can you charge a Tesla Powerwall with a generator? No, you can’t charge a Tesla Powerwall with a generator. The batteries for a solar system will only charge via solar panels or grid power. If the Powerwall is not connected to solar panels, then it will only charge from the grid.

Just because you cannot charge it using a built-in or even a portable generator, the Powerwall does have several integration options for augmenting your backup power.  

How Does a Powerwall Integrate with a Generator?

If you have a generator already installed or are going to install one after a Powerwall, it is essential to know how they work together.

The battery system will optimally be connected to the generator by an Automatic Transfer Switch (ATS) or a Manual Transfer Switch (MTS) should you want to exercise control on which backup to use first.

When installed by an electrician, the Powerwall will sit in between the main and the generator. Using an ATS will cause the backup to kick in once the batteries have fallen beyond a certain threshold. When using an MTS, you will have to physically change the switch, so the Powerwall toggles from charging to powering.

For solar users, the process is much the same as if you had a generator, with the solar panels generating electricity. Once the solar starts generating enough power to energize your home, the Powerwall will shut off and begin the process of charging once again.

The Automatic Transfer Switch manages your power transition so that it is seamless, rather than having to take a few seconds to moments ‘starting up’ as a generator has to.

If you have your generator on and a solar system running with the sun up, the generator will continue to power your home while the solar charges the Powerwall. You can interrupt this, allowing solar or the grid to take over the generator using an MTS. This procedure may seem inefficient compared to directly charging the device, but it improves energy output.

Charging Your Powerwall with an Alternative Source

Unfortunately, there is currently no way to charge a Powerwall besides connecting to the grid or solar system. The system’s nature requires it to be directly integrated by an electrician into a subpanel of a home. It is unsafe to connect a portable generator to power such a system.

As if you do energize your home, you could end up back feeding the grid. This back-feeding can be dangerous to line workers who do their diligent work to repair such things.

The problem with back feeding the line, or energizing it from your home rather than the power station, is that it can charge electrical cables while linemen work to repair outages.

Even if you have a solar system, your power will go out in a power failure event as the solar energize the utility lines and needs to be shut down. For this reason, having a battery backup can allow you not even to notice lines are down.

During times when the grid has failed, your solar system will continue to function should you have a Powerwall installed. In normal circumstances, when you generate too much electricity with solar panels, the excess electricity gets sent back into the power lines to feed the grid.

This process of providing back into the grid cannot happen during power outages, and thus, the Powerwall itself regulates the solar output, turning on and off as to not overfill the Powerwall.

This self-regulation allows you to keep generating energy and not cause a danger to those working on the grid.

Can I Connect Powerwall to Alternative Green Energies?

According to Tesla’s website, there is currently no integration with other eco-friendly energy sources.

As they state, “Powerwall does not currently work with existing battery systems or other renewable energy sources, such as wind or hydro.” This statement also, unfortunately, evidences the incompatibility with other battery systems.

Considerations in Charging the Powerwall

The Powerwall is itself intended to be a backup system should you need an alternative power solution.

The Powerwall is essentially a battery that is most efficient when installed with a solar system but can work without one. It connects to the grid and solar, using these to charge the battery and provide power should the primary power source fail.

You can configure your Powerwall to provide energy at certain times of day, reducing reliance on the grid. Those who want to use solar as much as possible can utilize it as a primary battery at night, taking over before energy from the grid is used.

Alternatively, for areas where electricity is priced at a premium or rationed, you can have it take on the task of powering your home at certain times of the day. Should the need arise, you can stack the Powerwall with up to nine others to accommodate an extensive amount of energy storage.

Keep Going Without Interruption

Because the Powerwall is installed where it is in the circuit, it takes advantage of seamlessly beginning to power your home in the event of a solar or grid failure. It does not suffer from being turned on, as it is a battery, not a generator.

During times of extended power outages, it can be rationed with other generators and solar to create an incredibly seamless distribution of electricity in your home. Using your appliances and having no interruption is essential and can save your home from unnecessary damage. 

If you seek to live an entirely energy independent lifestyle, having a battery such as this is a must. With its ability to change between solar and battery, having a system such as this allows you to operate your home at night without relying on other services.

Depending on your power usage and sunlight availability in your area, the combination of a robust solar system and battery can allow you to disregard other forms of electricity altogether.

Can I Charge My Car with A Powerwall?

Depending upon your configuration, you can use your Powerwall’s stored energy to charge your vehicle. During a power failure, your Powerwall can provide backup charging for your car.

Replenishing your vehicle during the day can allow for excess solar energy to be used for the car’s battery.

There exists no way to directly connect your car’s battery to a Powerwall system. Tesla does have an app that allows for control of the thresholds of power output.

Thus you can use the thresholds or time sync features, enabling your Powerwall to take over during car charging periods rather than using the grid.

Final Thoughts

Ultimately, the Powerwall and generator do not power or charge one another but rather work in tandem to provide seamless energy to a home. Both act as a way of energizing a building without charging the lines that lead to the grid.

By combining a battery like the Powerwall with a solar panel system, you may even be able to achieve independence from electricity providers.

It is important to note that generators do much the same job as a battery in the event of electrical failure. Neither is the perfect solution and while they do not integrate as of the time of writing, there is hope for the future.

Tesla is continually improving and integrating its technologies to supplement the growing ecologically conscious movement.

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The articles here on are created by Greg, a Tesla vehicle and Tesla solar expert with nearly half a decade of hands-on experience. The information on this site is fact-checked and tested in-person to ensure the best possible level of accuracy.

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