Generac PWRcell expert review: What makes it the most exciting new battery on the market?

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The Generac PWRcell home battery and inverter.
The Generac PWRcell home battery and inverter.

The Generac PWRcell (pronounced “power cell”) is a whole-home solar battery backup system from a trusted American company long-known for its backup generators. It all started in 2019, when Generac bought Pika Energy, the original developer of the PWRcell, and Neurio, a manufacturer of home energy monitoring equipment. 

By combining the technology from the acquired companies with know-how from over 60 years of making generators, Generac began marketing PWRcell to compete with the likes of the Tesla Powerwall and LG Chem’s RESU home batteries. 

So how does the PWRcell stack up? Below is our complete expert review of the PWRcell ecosystem of products, with analysis of specs and comparisons to other top batteries. But first, here are some important facts about PWRcell:

Key takeaways

  • Each battery cabinet can store between 9 and 18 kWh of energy using between three and six 3 kWh battery modules. Two battery cabinets can be combined for up to 36 kWh of storage.
  • PWRcell can deliver up to 12,000 watts of surge power to start heavy-duty appliances like well pumps and air conditioners.
  • When used with Generac’s Smart Management Modules, the PWRcell system can prioritize the startup of large appliances, allowing it to run more devices than any other solar battery system on the market.
  • The Generac PWRcell system can only be installed alongside a new solar system, and adds between $11,000 and $18,000 to the cost, depending on size of your system and where you live.
  • Additional 3 kWh modules can be purchased for around $2,000 and installed in the battery cabinet to add storage capacity as needs change.
  • Generac will debut a backup generator in early 2022 that will provide additional flexibility in off-grid situations by charging the PWRcell battery if it gets low when the sun isn’t shining.

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    Find out if going solar with battery storage is worth it in your area

    How the Generac PWRcell works

    Like other home solar batteries, the Generac PWRcell is designed to provide backup power in the event of a grid outage and to save homeowners money by helping them avoid costly peak energy charges under Time of Use (TOU) energy rate plans. 

    The PWRcell stores energy generated by your solar panels, and provides power to the home either when the sun doesn’t shine or when the grid is down. 

    Unlike other home solar batteries, Generac PWRcell is not just a battery box that hangs on your wall. Instead, it is an integrated system of components that work together to make the energy storage system more effective and efficient. Generac makes every piece of equipment for a home solar system, except for the solar panels and racking. 

    A PWRcell system includes the following main components:

    • SnapRS inline disconnect switches that go between each solar panel and allow for rapid shutdown in case firefighters need to work on the roof
    • PV Link substring power optimizers that take energy from the panels and send it to the battery and inverter
    • PWRcell battery modules to store solar energy, inside a specially-designed battery cabinet
    • A PWRcell solar islanding inverter that connects everything together and sends power to the electrical panel in your home

    Here’s how they all fit together:

    generac pwr cell diagramThe main components of the Generac PWRcell system. Image source: Generac

    Now let’s look at each of these components.

    SnapRS switches and PV Link optimizers 

    These are fairly straightforward pieces of hardware that have an important job in the PWRcell system. 

    The SnapRS switches connect between each solar module in an array and will shut down the output of that module within 10 seconds from whenever the inverter is turned off. Rapid shutdown is a fire code requirement of solar systems, and these switches are how Generac accomplishes this task.

    The PV Link boxes are substring power optimizers. They attach between a short string of solar panels (up to 2500 W) and the inverter, and ensure that the DC power delivered by the panels gets sent to the inverter as soon as panel output reaches 60 volts. The PV Link was initially developed by Pika Energy to integrate with the PWRcell battery. 

    Because they optimize the power output of a string of panels, the PV Links are somewhat less efficient than microinverters and DC power optimizers, which are attached under each solar panel in an array. The advantage of the PV Link is having fewer points of failure, at the expense of a little less energy output over time. For people who want the extra juice, Generac has announced its own microinverters, which will be available in 2022 (more on these below). 

    The PWRcell battery cabinet 

    The PWRcell battery cabinet can hold up to 6 modules, each of which can store 3 kWh of usable electricity. The cabinet can be set up with 3, 4, 5, or 6 modules, allowing 9 - 18 kWh of storage. Here’s how that looks:

    Generac’s modular battery cabinet designGenerac’s modular battery cabinet design allows for future capacity expansion. Image source: Generac

    The battery is charged using DC power sent directly from the solar panels. This makes the battery very efficient compared to batteries like the Tesla Powerwall and sonnenCore, which charge using energy that gets converted from DC to AC and back again, causing some loss of energy in the process. 

    The downside of this DC-coupled design is that PWRcell batteries cannot be added to an existing home solar system without rewiring everything at great expense. The PWRcell is meant for new solar installations only, and actually, the battery itself is optional. If you think you may want Generac battery backup in the future, you can get a solar system installed that includes the SnapRS, PV Link, and PWRcell inverter, and add the battery cabinet at a later time.

    Learn more: Is a DC or AC battery right for your home?

    The PWRcell inverter 

    The Generac PWRcell inverter was designed to operate a home in grid-connected or “islanding” mode in case the grid is down. It can be set by the homeowner to one of several modes, including backup power, self-supply, time-of-use, and zero-export. 

    The inverter comes in two models: 

    • X7602, which can provide up to 7,600 W of single-phase AC power when connected to the grid
    • X11402, which can provide up to 11,400 W of 3-phase AC power when connected to the grid

    Most homeowners will end up with the X7602, while commercial businesses are the target customer for the X11402.

    Both inverters can accept up to 30 A @ 420 VDC from solar panels, and both output 9,000 W continuously in islanding mode when connected to one 18-kWh PWRcell battery. Both inverters can deliver up to 12,000 W to start a motor. That’s a very impressive number, as it means a PWRcell inverter can start a well pump, sump pump, or a 3-ton HVAC unit. Compared to Tesla Powerwall’s max peak output of 7,000 W, the PWRcell is much better.

    Optional components in the PWRcell system 

    In addition to the required components, Generac also makes some optional pieces of equipment to provide extra flexibility. They are:

    • Automatic transfer switch (ATS)
    • Smart Management Modules (SMMs)
    • Sure-Start HVAC soft start box

    This is where the PWRcell system really eclipses other home energy storage solutions. Generac brought these components from their home generator business to complement the PWRcell battery. The ATS and SMMs automatically shut certain appliances down, based on priority, to start up other appliances that require high surge power. 

    Using these components, homeowners can run nearly their entire home on a single backup battery in the event of a grid outage—something many other companies’ batteries can’t provide. Altogether, this makes the Generac PWRcell one of the most exciting home batteries on the market

    Automated Transfer Switches 

    These specialized pieces of equipment are meant to control multiple HVAC units. Using a Generac ATS can allow one PWRcell inverter to manage up to 4 individual HVAC units, turning them on and off so they don’t overload the inverter’s capacity by starting all at once.

    Smart Management Modules 

    Generac SMMs are small boxes that contain hardware to turn a given circuit off and on, based on how much of a priority it is to keep powered. They are installed in-line, which means they need no external power or communication—the circuits are turned on or off via a powerline signal from the PWRcell inverter. 

    Basically, when the appliance wants to start, the SMM tells the inverter to check whether it can. If a higher-priority appliance is running, the SMM will not allow its appliance to start up. When the higher-priority device is no longer running, the SMM allows the lower-priority device to start. This way, the home’s appliances can all run off the same inverter and not overload the circuit by all drawing power at once. 

    Sure-Start HVAC soft start box 

    This piece of equipment is used to reduce the start-up current that an air conditioner compressor needs. It further reduces the peak power consumption needed and allows the PWRcell system to keep running essential equipment as an air conditioner starts.

    How Generac’s optional components work 

    Here’s a look at how SMMs and a Sure-Start box work within the PWRcell system:

    pwrcell smm diagramImage source: Generac

    The image above shows how the PWRcell can power three of the most important appliances in the home as it operates in a grid-down situation. Here’s what’s happening, from bottom to top right in the image:

    • The sump pump is wired without an SMM so it will always receive power when it needs it
    • The well pump is set to Priority 1 using an SMM to turn it on whenever it needs to run to supply water to the home
    • The 3-ton A/C is set to Priority 2 and allowed to run when the well pump is not running. A Sure-Start box is attached to keep the current it draws from overwhelming the inverter
    • The 5-ton A/C is set to “lockout” using an SMM, which means it will not turn on when the grid is down, because it would draw more power than the PWRcell inverter can provide

    Generac’s PWRview monitoring app 

    Another optional addition to your PWRcell system is Generac’s PWRview monitoring app. 

    It’s a one-stop shop for information about energy generation and usage in your house. The app contains data on solar generation, battery charge, grid usage, and more - and can even give you an estimate of your next utility bill based on that data it’s collected, if you enter your rate plan.

    It certainly sounds like a good app to have, and its functionality is similar to other solar monitoring solutions from equipment manufacturers and solar installers. Unfortunately, reviews of Generac’s Android and iOS apps are not positive. Users complain about glitches, missing data, bad customer service, and more. This seems to be one area where Generac has stumbled, in regards to its PWRcell system.

    If you’re curious about how the app works, check out the below video about its features.

    Cost and availability

    Generac’s PWRcell components are sold through a nationwide network of licensed dealers, so pricing can vary, depending on the area where you live. That said, we do have some pricing information.

    Generac has said that a minimum-size 9 kWh PWRcell system will cost about $10,000, plus installation costs, which we estimate will be between $1,000 to $2,000 more than a solar installation without a PWRcell. 

    Each battery module can be purchased separately for $1,900 - $2,000, so the cost of a full-sized 18 kWh PWRcell system ranges from about $16,000 to $18,000 installed, depending on offers from dealers in your area.

    The good news is that the PWRcell is eligible for solar storage incentives in certain areas. Not only that, when you install a solar system, you can claim the 26% federal solar tax credit. These incentives (as well as other applicable incentives and rebates you may qualify for) can reduce the cost of a solar-plus-battery-storage system substantially.

    Find out which incentives and rebates you qualify for when you install solar

    PWRcell warranty information

    Generac is a solid, reputable company that stands by its products. You can count on it to be around for decades to come. While that’s a good basis for trusting a warranty, the numbers need to be right. Let’s see how well they fare when it comes to offering their customers protection against product failures.

    The good news is, the Generac PWRcell warranty covers parts, labor, and limited travel (100 miles/3 hrs maximum, per occurrence) for all components of the PWRcell system. The length of coverage depends on the product type and Generac promises the products will be free from defects in material and workmanship during their coverage period. 

    Here’s a look at how long each component is covered:

    Generac PWRcell warranty information
    Component Warranty coverage
    PWRcell battery cabinet 10 years
    PWRcell battery modules 10 years or 7.56 MWh of energy throughput per module; whichever comes first
    PWRcell inverter 10 years
    PV link 25 years
    SnapRS 25 years

    Importantly, the pieces that are going to stay up on your roof for 25 years (PV Link and SnapRS) are warrantied for 25 years. The PWRcell inverter and battery come with 10-year warranties, which is fairly standard in the industry for these components. 

    Additionally, the throughput warranty for the battery modules is fairly standard. To put it in perspective, if you drained each battery module 100% of its usable power (3 kWh) every day, you’d get to 7.56 MWh in about 6.9 years. The vast majority of people will choose to retain some battery capacity for emergencies, and therefore, will use less. To get to the full 10 years, don’t go over an average of 69% drain per day.

    Unfortunately, the PWRcell battery module warranty doesn’t say anything about how much capacity the modules will retain over those 10 years; only that they will be free of defects in materials and workmanship. If you think the batteries have lost more capacity than they should, it’s up to you to convince Generac of that, and up to them to agree with you.

    This isn’t normal. Many other batteries on the market, including the Tesla Powerwall and its main competitors, guarantee between 60% and 70% of the original capacity at the end of their warranty periods. This is an oversight for Generac. We’ll update this article if that changes.

    Can you go off-grid with Generac PWRcell?

    Going off-grid with solar is not for the faint of heart. In general, you need to oversize your solar system and battery capacity to generate and store enough electricity to get through 2-3 days with little to no sun, something you very well may experience - especially in winter time.

    Despite that, when it comes down to it, the Generac PWRcell is better-suited for an off-grid lifestyle than most other solar batteries. The modular battery can be hooked up with as little as 9 kWh of storage capacity or as much as 36 kWh in two cabinets. Using Generac’s SMMs and ATS as described above can allow you to run a good deal of home appliances off of one or two PWRcell inverters. 

    That said, unless you spend a lot of money to oversize your solar system, you’re going to need some form of backup generator. Many off-gridders turn to a fossil fuel generator on winter days when their solar systems aren’t producing enough and their batteries are low on energy. 

    The PWRcell system does not currently interface with Generac’s line of backup generators, but the company recently announced a new product they’re calling PWRgenerator. It’s a 9 kW backup generator designed to interface with the PWRcell system that runs on either natural gas or liquid propane.

    The Generac PWRgenerator, coming in 2022.

    When the PWRgenerator becomes available, it will work by acting as a backup to your backup

    The system will detect whenever the PWRcell battery discharges to 30%, then turn on PWRgenerator to recharge the battery to full. Generac says the generator can charge the 12-kW battery from 30% to full in about an hour.

    The generator is scheduled to be available in early 2022, and there is no word on price yet. Generac’s existing 9 kW home generators start around $2,800 plus installation costs. We’re guessing the PWRgenerator will add about $4,000-$5,000 to a PWRcell system, all-in.

    Here’s the good news for existing PWRcell owners, and those who buy before 2022: Generac has told SolarReviews that as long as a homeowner has an unused DC breaker in their PWRcell inverter, they can add a PWRgenerator.

    How PWRcell compares to other top home batteries

    We’ve made allusions above to how PWRcell compares to Tesla’s Powerwall, but let’s make the facts more explicit here, and add a comparison to LG Chem RESU Prime batteries, which are another of the top home energy storage solutions.

    PWRcell differs from the Powerwall and RESU batteries in a couple of key areas: 

    • PWRcell is a DC-coupled, modular battery system that comes with a lot of other solar equipment, must be installed at the same time as a new home solar system, and can be purchased in multiple capacity sizes
    • Tesla Powerwall is a single AC-coupled battery box that can be added to an existing solar system, and comes in one size (though multiple Powerwalls can be installed together)
    • LG Chem RESU Prime batteries are DC-coupled batteries that come in 9.6 and 16 kWh sizes and can be added to an existing solar installation

    Here’s a comparison of key data points of these three market-leading home energy storage solutions:

    Generac PWRcell specs vs. Tesla Powerwall and LG Chem RESU Prime
      Generac PWRcell Tesla Powerwall+ LG Chem RESU Prime
    Power connection DC AC DC
    Battery chemistry Li-NMC Li-NMC Li-NMC
    Capacity 9 - 18 kWh 13.5 kWh 9.6 - 16 kWh
    Max. continuous output 4.5 - 9 kW 5.8 - 9.6 kW* 5 - 7 kW
    Peak power output 6 - 12 kW 10 - 22 kW* 7 - 11 kW
    Round-trip efficiency 96.50% 90% >90%
    Warranty 10 years 10 years 10 years
    Throughput warranty (MWh per kWh of storage) 2.52 2.8 3.35
    End-of-warranty capacity N/A 70% 70%
    Average installed cost $11,500 - $17,000 $10,500 $9,000 - $12,000
    Energy monitoring app Yes Yes 3rd party
    EV charging in-app No Yes No
    Load prioritization Yes No No

    *Tesla Powerwall+ output depends on whether the grid is up or down, and also increases when paired with a solar installation of at least 4 kW under full sun. A solar installation of more than 12 kW is necessary for peak power output of 22 kW.

    One thing we can’t capture with a single data point is availability

    As of September 2021, both the Generac PWRcell and LG CHem RESU Prime batteries are available from installers all around the country, while the Tesla Powerwall has at least a 3-6 month waiting period after ordering. All of the batteries listed above can be installed by many different solar installers, so contact companies near you to get quotes for solar and home energy storage.

    The future of Generac’s PWRcell

    In September 2021, Generac announced several new products that will become available in early 2022. 

    First up is the aforementioned PWRgenerator, which will allow PWRcell owners to have extra peace of mind in grid-down or off-grid situations. The generator will run on natural gas or LP and charge the PWRcell batteries if they get too low. 

    Next are PWRmicro microinverters that can be used in a PWRcell system in place of the SnapRS and PV Link equipment. These pieces of equipment make it possible to optimize the output of one or two solar panels at a time, squeezing just a little extra efficiency out of the system and providing more accurate monitoring.

    Finally is a new piece of smart technology called the PWRmanager. This box goes next to your home’s main electrical panel and intelligently controls all the circuits in your home to ensure the PWRcell system is never overloaded. It’s like an advanced version of the SMMs discussed above, and can be included in the PWRcell system as an option.

    Bottom line: Is the Generac PWRcell system right for you?

    As we outlined above, the Generac PWRcell is an exciting entry into the home energy storage market, and has some unique features that set it apart from the competition. If you’re looking for home battery backup for emergencies that can also help you avoid high peak energy costs under a Time of Use billing plan, the PWRcell is an excellent choice.

    If you’re looking for a solution that can take you off the grid, the PWRcell may be just right for that too - especially after Generac releases the PWRgenerator “backup to the backup” in 2022. It won’t be as hearty as some true off-grid solar setups on the market, but it should be a heck of a lot more user-friendly.

    The tradeoffs here are a somewhat higher price than the batteries from Tesla and LG, and the missing end-of-warranty capacity guarantee. Still, if you haven’t yet installed solar and are looking for a robust home battery system and you need to run critical appliances like a well pump, sump pump, and A/C during an outage, the PWRcell is probably the best battery on the market.

    Find out if going solar and installing a solar battery like the Generac PWRcell is right for your specific home by using our solar panel cost and savings calculator below.

     

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     - Author of Solar Reviews

    Ben Zientara

    Solar Policy Analyst and Researcher

    Ben is a writer, researcher, and data analysis expert who has worked for clients in the sustainability, public administration, and clean energy sectors.

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