Tesla Powerwall vs. Generac: Which to Get Revealed


Tesla Powerwall vs. Generac: Which to Get Revealed

The Tesla Powerwall and the Generac PWRcell are both backup battery systems for residential and commercial use. Naturally, there are advantages and disadvantages to both, so which one should you get?

The Tesla Powerwall is an AC-coupled battery, while the Generac PWRcell is a DC-coupled battery; these batteries also differ in terms of energy capacity, power, and installation process. However, the Powerwall offers a few more benefits over its counterpart.

If you are in the market for a battery backup system for either solar panels or the grid, then you are highly encouraged to continue reading about the differences between the Tesla Powerwall and the Generac PWRcell. By the end of the article, you should be able to determine which option best suits your needs.

Which Is Better: Tesla Powerwall or Generac?

Battery storage systems are primarily paired with solar panels. As long as the sun continues to provide energy to the panels mounted on the home, some of that energy will be transferred to a battery backup system like the Tesla Powerwall or Generac PWRcell.

You can use this stored energy to power your home at any time of your choosing. Many customers rely on these systems to power their homes during utility outages.

At this point in time, it appears that the Tesla Powerwall is slightly better than the Generac PWRcell for a variety of reasons:

  • The Tesla Powerwall is slightly more affordable than the PWRcell.
  • The Powerwall is an AC-coupling battery and can be paired with just about any solar inverter.
  • The Powerwall is simpler to install due to its integrated components.
  • The Powerwall has been around longer and has built up a more extensive network of support for users.

In contrast, with the Generac PWRcell:

  • There are fewer inversions required because it is a DC-coupled battery.
  • It’s easier to customize during the installation process.
  • The PWRcell offers a more potent punch of max continuous power.

As you can see, the Tesla Powerwall offers a few more benefits users can easily take advantage of over the Generac. However, depending on your situation, you may prefer to use the Generac over the Powerwall. In these next few sections, we’ll cover a few more similarities and differences between the two battery storage systems so you can decide which one is best for you.

Can Powerwall or the Generac Be Used Off-Grid?

Neither of these technologies can currently be used to store battery power for off-grid living. Their primary purpose is to offer several hours’ worth of backup electricity. They do not have the battery capacity to be used for an extended period without being sufficiently recharged.

Tesla does offer exciting news, though, for those who hope to one day live entirely off the grid. The manufacturer has announced its intentions to develop a battery system in the future that will have full off-the-grid capabilities.

Generac advertises its product as one that will help users gain some independence from the grid. Perhaps someday, they also will develop equipment with this capability. However, their website does not yet show any intentions of creating such a battery.

Powerwall vs. Generac: Cost

Both the Tesla Powerwall and the Generac PWRcell are eligible for a tax credit of up to 26%, as long as you live in a jurisdiction where tax credits and rebates are indeed offered. If you have any questions regarding your eligibility for a tax credit or rebate, you are encouraged to speak with local government or utility officials.

Note: Due to local variability, the cost estimates cited below do not include any rebates or tax credits. Installation costs are included. These estimates are based on manufacturer recommendations for a home with 7.6 kWh worth of solar panels.

Tesla PowerwallGenerac PWRcell
Cost = $37,584Cost = $43,544
2 Powerwalls = $14,0409 kWh Battery Storage System = $20,000
7.6 kWh Solar Panels = $23,5447.6 kWh Solar Panels = $23,544

(Source: Tesla and Generac)

The project’s final cost will depend significantly upon whether you decide to use energy from the electrical grid or solar panels mounted on your house. However, the Tesla Powerwall holds great potential to cost a little bit less than the Generac because it is an AC-coupled battery system.

Which Battery Helps You Save the Most Money?

Although Tesla’s Powerwall may help you save on initial costs, it’s also worth considering which battery storage option will save you the most money in the long-term. 

  • Powerwall: One neat feature that Tesla offers is time-based control (aka Load Shifting) that specifically prioritizes charging during low-cost times and then discharging during times when energy prices are higher; this will help ensure that you get the best return possible from your solar energy production.
  • ●     Generac PWRcell: Generac has developed a home energy management system that operates on an Automatic Transfer Switch (ATS) and Smart Load Management Modules (SMMs); this is designed to alleviate the need for the battery system to shed energy loads in the event of a blackout.

Commercial and Residential Solar Subscriptions

The Tesla Powerwall can be preferable in the commercial setting due to the manufacturer’s solar subscriptions. These are currently available only within the confines of the state of California. However, it is not unreasonable to expect this service to be someday offered in more states.

A solar subscription allows homes and businesses an opportunity to receive power from commercial solar panels rather than installing and owning their own units; this removes the need for you to commit to a solar contract.

The subscription itself does not come with a Tesla Powerwall or a Powerpack (an extensive network of batteries that can store up to 240 kW.) It still offers the potential for savings, though, as you will not incur the cost of installing the panels. The downside is that you will not enjoy the same benefits as those who have a Powerwall attached to both an on-site solar system and the electrical grid.

This is an area where the Tesla Powerwall does have an advantage over the Generac PWRcell. Tesla’s influence in the market has allowed the company to build a network of partnerships that is currently unparalleled. If you are looking for a battery backup system in the commercial/industrial setting, you’d be hard-pressed to find a more versatile option than the Powerwall.

Powerwall vs. Generac: Warranties

Both Tesla and Generac offer warranties for their products, although there are some critical differences in their programs’ specific terms. At this point in time, Tesla backs their product with a more consumer-friendly warranty than Generac does:

  • Tesla Powerwall
    • Length of warranty: 10 years
    • Tesla warrants that the Powerwall will be free from defects for ten years following the initial installation.
    • The Powerwall will retain 70% of its battery capacity for ten years following the initial installation date.
    • The battery will go an unlimited number of cycles if it is only used as a backup in a solar self-consumption system.
  • Generac PWRcell
    • Battery Cabinet: 10-year warranty
    • Battery Module(s): Warranty of 10 years or 7.56 MW of energy throughout the modules, whichever comes first.

The basic terms of each warranty, as shown above, would suggest that Tesla offers the consumer more options to retain at least a portion of their original purchase price if the system wears down prematurely.

AC Coupling vs. DC Coupling

The Tesla Powerwall is AC-coupled while the Generac is DC-coupled. There are pros and cons to each coupling method. The solar panels themselves generate DC electricity that must be converted to AC electricity for the appliances inside a home. When it comes to transforming this energy, these are the key differences between AC and DC-coupled systems:

  • AC-coupled systems: electricity stored within the battery needs to be inverted three separate times before it can be used.
  • DC-coupled systems: electricity produced by the solar panels only needs to be inverted once.
Pros of AC-CouplingPros of DC-Coupling
Simple to install.More efficient due to fewer inversions
Batteries can be recharged from both the solar panels and the electric grid.Solar panels already produce DC (direct currents).
It tends to cost less than DC-coupling. 
It is compatible with any inverter. 

AC-coupling systems have traditionally been more common in residential and commercial applications, although DC coupling batteries have gained popularity in recent history.

Powerwall vs. Generac: Energy Capacity

Energy capacity here refers to the amount of electricity that the battery can actually hold without recharging again. These numbers refer to the highest possible energy capacity that a single battery or battery case can store for each respective brand.

Tesla PowerwallGenerac PWRcell
13.5 kWhUp to 18 kWh
100% depth of discharge84% depth of discharge
90% round trip efficiency96.5% round trip efficiency

(Source: Generac, EnergySage, and Pika Energy)

Depth of discharge and round trip efficiency are not terms that most are familiar with, but that doesn’t make them unnecessary as a point of comparison.

  • Depth of Discharge (DOD): refers to the percentage of battery that has been discharged relative to the battery’s overall capacity. This number helps you determine how much of the battery you can use without recharging.
  • Round Trip Efficiency: this number describes the fraction of energy put into storage that can be retrieved. A higher number means that the system operates more efficiently.

But why does the depth of discharge matter? Well, this number tells you how long you should go between charges. Exceeding the depth to discharge will result in battery damage and a shortened lifetime.

Since the depth to discharge of the Powerwall is 100%, this means that you can use 13.5 kWh between charges. With the Generac, you can use up to 15.12 kWh of battery between charges.

Powerwall vs. Generac: Power

The power category being referred to here is the maximum continuous power being ejected by the battery system. This is one area where the Powerwall and the PWRcell differ significantly, with one packing a bit more of a punch at the surface.

Tesla PowerwallGenerac
Real Power (Max Continuous): 5 kWReal Power (Max Continuous): 9 kW

(Source: Tesla and Generac)

Power is a measure of the maximum amount of electricity that can be output in a single moment. The Generac does deliver four more kW of continuous power than the Powerwall and holds a reputation for providing an impressive amount of energy for instant use.

If you need more power out of your backup battery for all your appliances, you can always add more battery backs to your setup.

  • Tesla notes that it is not an uncommon or inconvenient practice to mount multiple Powerwall units along the same wall. They can be stacked either side-by-side on the wall or front-to-back on the floor. (Note: Groups of more than three Powerwalls are not recommended for floor installations.)
  • A Generac PWRcell is generally used to support three to six different battery modules, which can deliver up to 9 kW of continuous power. If more continuous backup power is needed, it is possible to connect multiple PWRcell batteries to a single inverter until 11 kW of continuous backup power is achieved.

How Many Batteries Can You Link Up to a Single Inverter?

One limitation that you may run into during the process is the number of batteries that can be supported by a single inverter in a solar backup battery setup. You will see here why the Tesla Powerwall appears to have an advantage in this regard:

  • Tesla Powerwall: The inverter is integrated; the Tesla Powerwall has less hardware than the Generac PWRcell because the inverter is integrated within the Powerwall itself. Up to six different Powerwalls can be stacked together.
  • Generac PWRcell: Two—you can link up to two different PWRcells to a single inverter; this means that you can link two separate battery compartments up to a single inverter. Each battery cabinet can support up to 6 different modules. If you max out on battery modules for a single inverter, you will have an energy capacity of 36 kWh.

Powerwall vs. Generac: Dimensions and Weight

The Tesla Powerwall and the Generac PWRcell are not carbon copies of each other when it comes to specific components:

  • The Powerwall is more so one cohesive piece, with an integrated solar inverter available.
  • The Generac PWRcell comes available in several different configurations, depending on how many battery modules you would like to place within the cabinet.
ParameterTesla PowerwallGenerac (Power Cabinet)Generac (Inverter)
Dimensions45.3” x 29.6” x 5.75”22″ x 10″ x 68″24.5″ x 19.25″ x 8″
Weight251.3 lbs.115 lbs.62.7 lbs.

If you’re going to compare the Powerwall and Generac PWRcell, you need to consider the size of both the inverter and the power cabinet together. You will notice that the Tesla Powerwall is similar to the Generac PWRcell when you combine the inverter and power cabinet dimensions.

The big difference here is the weight. The Powerwall does weigh considerably more than the PWRcell. This weight difference has a lot to do with the simplicity of the Powerwall setup. There are fewer individual components required during the installation of this system than is the case with the Generac PWRcell.

Powerwall vs. Generac: Installation

The manufacturers caution customers to hire a trained and licensed electrician to install these systems. In no case is either of these systems simple enough for a DIY installation. You will want to consult the professionals anyway, as they will be able to provide you with guidance on which materials you need to size your backup battery appropriately.

Installing the Tesla Powerwall

To install the Tesla Powerwall in your home, you would follow these steps:

  1. Start with an energy source: either the electrical grid or solar panels.
  2. The necessary wiring is performed.
  3. The Powerwall battery pack(s) is installed. (A single battery has an energy capacity of 13.5 kWh. Tesla may recommend that you install multiple battery packs to meet your energy demands.)
  4. A solar inverter must be installed to convert the direct current from the panels to alternating current. (The Powerwall 2 comes with an integrated solar inverter.)
  5. A backup gateway is installed. This component manages the connection between the electrical grid and the Powerwall.

Installation of Generac PWRcell

The Generac PWRcell’s installation will follow a similar process as the Powerwall, with a few distinct differences in its later steps:

  1. Start with an energy source: either the electrical grid or solar panels.
  2. The necessary wiring is performed.
  3. The inverter is installed, typically in the garage.
  4. The Battery Cabinet is mounted, typically in the garage.
  5. Battery modules are attached to the Battery Cabinet. (The number of modules determines the actual battery capacity and power. There are four different configurations currently available: 17 kWh, 15 kWh, 12 kWh, 9 kWh.)

The bottom line here is that you have more of a chance to appropriately-size your battery system if you go with the Generac PWRcell, thanks to the availability of both 12 kWh and 9 kWh configurations. In contrast, the Powerwall comes standard in a 13.5 kWh battery. However, one thing that’s definitely nice about the Powerwall is the compact design, with newer models coming with a solar inverter already integrated into the battery pack.

Can the Powerwall or Generac Be Installed Outdoors?

Both batteries are suitable for storage outdoors, so there is no clear favorite here. The electrical hardware provided will indeed vary by location, so be sure to check with your certified installer to ensure that the appropriate materials are being used.

  • The PWRcell comes equipped with an outdoor-rated battery cabinet, including the additional mounting hardware necessary for outdoor installations. Outdoor mounting hardware becomes essential as a result of ground clearance and support requirements.
  • The Tesla Powerwall can also be installed outdoors. The equipment is fully operational in a wide range of temperatures: -4 degrees Fahrenheit to 122 degrees Fahrenheit.

Anyone experiencing extreme temperatures one way or the other is encouraged to install their battery backup system indoors. Otherwise, it could become subject to damage from excessive sunlight and extreme weather conditions.

Do I Need to Hire a Contractor to Install the Solar Panels?

The good news is that both Tesla and Generac have partnered with local installers to ensure a seamless process from installing the solar panel to the battery pack; this includes educational training specific to installing either a Powerwall system, a Generac PWRcell system, or both.

The manufacturer also has engineers on staff who will help guide every step of the equipment selection process. You will be informed which configuration best suits your home’s energy demands.

How Much Hardware is Needed for Installation?

Some customers have an understandably lukewarm attitude towards the extensive network of hardware that must be mounted to their roof if they decide to go with a solar panel installation. Tesla reportedly uses 30% fewer anchor points on the roof than what is seen in traditional installations.

Tesla Solar Roof

Tesla has also engineered a less intrusive strategy for solar energy capture called a solar roof. A solar roof by Tesla involves installing roof tiles that look similar to standard composite roof shingles from afar but can capture energy from the sun in the same fashion that a solar panel would.

The solar roof is also stronger and more durable than a typical roof shingle. Solar shingles are made of tempered glass, silicon solar cells, Tedlar, aluminum, and shingle housing. Even with all these added components, they can still be less bulky than most standard asphalt shingles.

You can expect a solar roof to cost approximately $16,260; this has the potential to be more affordable than the traditional option of outfitting a roof with asphalt shingles and solar panels, especially if your shingles are made of a premium composite.

At the very least, you will have a solar power system that is less intrusive if you do decide to go this route; this is not something that you can necessarily do with the Generac PWRcell, especially at this price point.

Powerwall vs. Generac: Mobile App Support

Both Tesla and Generac provide users with mobile app support for their respective battery systems. These allow users the opportunity to monitor their home’s energy consumption and solar generation.

Also included with app support is:

  • You can track utility bill estimates and savings.
  • Keep track of the duration of time that you have used the battery.
  • Gain access to energy-saving opportunities.

Which Battery System is More Popular?

The Powerwall is currently the more popular option. By comparison, the Generac PWRcell hasn’t been around nearly as long. As a result, you will find features that the Powerwall has that haven’t yet been worked into the PWRcell system quite yet.

Product Development

Another advantage for the Tesla Powerwall is that the company has had more years of trial and error to finely-tune its product. The current version of the Powerwall is actually the second edition, hence the moniker, “Powerwall 2.”

The original Powerwall, first launched in 2015, was capable of providing 7 kWh of energy for daily applications. The Powerwall 2 has been offering users an enhanced version of the original since 2016.

The Generac PWRcell became available nationwide in January 2020. The fact that the Tesla Powerwall has been around longer doesn’t necessarily make it better in and of itself. However, users who are adamant about purchasing a time-tested technology are sure to find Tesla’s product more suitable at this point in time.

Sales

Tesla reported an enormous increase in the sales of Powerwall units during 2019. By July of 2019, Powerwalls had been installed at more than 50,000 different sites. What’s more impressive is that this occurred after the company used all of the cell capacity at its Gigafactory 1 location solely to supply its Model 3 electric vehicles with battery packs in 2018.

Still in its infancy, the Generac PWRcell is experiencing rapid growth in the residential sector. Sales jumped 27.2% in the second quarter of 2020. These results haven’t exactly been replicated in the commercial and industrial sectors, where sales dropped 32.8% over a year.

Final Thoughts

Although the Generac PWRcell is a recent entry to the market, it does hold some advantages over the Tesla Powerwall. Among these advantages is the inclusion of a more significant number of battery module options, a greater battery capacity, and more instantaneous power.

The Tesla Powerwall still comes out favorably because of its time-tested technology and compact package, not to mention more generous incentives from Tesla to invest in solar energy systems. The Powerwall batteries are also not challenging to mount up next to each other if you need multiple battery packs to service your energy demands.

Solar Discounts:

Greg

Hi, I'm Greg. My daily driver is a Tesla Model 3 Performance. I've learned a ton about Teslas from hands-on experience and this is the site where I share everything I've learned.

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