Described as a “rechargeable lithium ion battery with liquid thermal control,” the Tesla Powerwall is a battery for home energy storage. The first Powerwall was launched in April 2015 and updated models—Powerwall 2.0—were announced in October 2016 and November 2020, respectively.

With the recent passage of the Inflation Reduction Act, many homeowners are interested in pairing a home battery with a solar panel system. With plenty of great benefits to add solar + battery storage to your home, it’s important to research the Powerwall beforehand.

Key Things to Know About the Tesla Powerwall

The Powerwall is a home battery that stores the energy your solar system generates. This energy can then be used to power your home at night or during low-output days when your solar system isn’t producing as much electricity.

When evaluating the Powerwall, it’s important to take into account various key metrics and technical specifications. There are many important factors to consider when choosing a battery, including:

• The size of the battery (power and capacity), 
• Its chemistry, depth of discharge, and 
• Roundtrip efficiency.

Size

The Tesla Powerwall only comes in one size: 14 kilowatt-hours (kWh). When comparing the Powerwall to other home battery storage solutions, two important metrics to evaluate are power and usable capacity.

Power, measured in kilowatts (kW), determines how much electricity can be produced at any given time. The usable capacity (measured in kilowatt-hours, or kWh) of a battery is the maximum amount of electricity it can store when fully charged. The Tesla Powerwall has a maximum power rating of 7.0 kW and has 13.5 kWh of usable capacity.

The Powerwall is also a modular system, which means that you can add multiple batteries to your storage setup. For example, if your home has high energy demands and usage, you might want to install multiple Powerwall batteries. According to Tesla’s website, you can add up to 10 Powerwall batteries to form a massive energy storage system.

Think of your battery like the flow of water through a pipe. The usable energy capacity is the amount of water that can flow through the pipe, while the power rating is the size of the pipe. The larger the pipe, the more water that can flow through at once, which depletes the water faster. Likewise, a battery with a high power rating can deliver more electricity at once compared to a low-capacity battery, but will also burn through its energy capacity faster.

The amount of power your battery can deliver determines which appliances it can power at the same time. The battery’s usable capacity determines how long those appliances will run without the need to recharge.

A battery with a higher power rating can supply more electricity to run robust appliances or multiple appliances at once. Batteries with a larger usable capacity store more total energy, which means they can keep your devices running longer on each charge.

Basic Functionality

The functionality of solar batteries can vary; some batteries have excellent off-grid capabilities, while others offer solutions tailored for rate arbitrage. 

Here are the important qualities you need to know about the Tesla Powerwall:

Backup Power

Backup power is the ability of a battery to provide electricity for your home during an outage. The amount of backup power you’ll have depends on how much energy your home uses and how long your backup battery can run.

Tesla has made a concerted effort to ensure their battery solution is compatible with most common brands and types of off-grid and hybrid inverters. This means that, as long as the correct components are installed, your Powerwall will provide backup power for your home when the grid goes down.

Chemistry

The Tesla Powerwall is a lithium-ion battery, specifically a type of lithium nickel manganese cobalt oxide (NMC) storage product. NMCs are one of the most common lithium-ion battery technologies. They’re also known for their energy density and increased safety. Compared to other types, NMC batteries can store more energy in less physical space while still remaining safe to use.

Performance Metrics

Two metrics that can be used to evaluate the performance of a solar battery are the depth of discharge and roundtrip efficiency.

Depth of discharge (DoD) refers to the percentage of a battery’s total energy that has been used, or discharged, relative to its overall capacity. A battery’s useful life decreases each time you charge, discharge and recharge (or cycle it). Because of this, many manufacturers specify a maximum DoD level for optimal battery performance. 

Batteries with a higher depth of discharge are generally considered to be better quality products. The Tesla Powerwall’s 100% depth of discharge, based on its advanced lithium-ion battery chemistry, makes it a remarkably safe power source for your home.

Roundtrip efficiency measures how much electricity is lost when charging and discharging a battery. A higher efficiency percentage is indicative of a battery’s ability to convert incoming electricity into stored electricity and back into usable electricity again. The Tesla Powerwall’s roundtrip efficiency is 90%. This means for every 10 kWh of energy you put into the battery, 9 kWh will be available to use.

Conclusion

The Tesla Powerwall is a game-changer in the world of home energy storage and solar power. This home battery is an increasingly popular technology, providing peace of mind during power outages and is a great option that will make your home more sustainable for years to come.

To determine if solar and a Tesla Powerwall battery is right for your home energy needs, our certified Solar Technologies representatives can answer all your questions. If you’re ready to change the way you power your home, contact us today for a free customized quote.