Generac PWRcell battery cost guide & review

In 2019, Generac acquired battery manufacturer Pika Energy and has since integrated their technology into the launch of their own Generac-branded home storage solution: the Generac PWRcell. Having long been a leader in the backup power space, Generac is now moving into clean energy and energy storage, with the PWRcell line of batteries at the forefront of their new product fleet.

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The Generac PWRcell pairs well with solar panel systems, especially if your utility has reduced or removed net metering, introduced time-of-use rates, or instituted demand charges. Installing a storage solution like the Generac PWRcell with a solar energy system allows you to maintain a sustained power supply during the day or night as long as you store enough power from your solar panels when the sun is shining.

As with many other home battery products, the Generac PWRcell is sized for day-to-day use at your home and is primarily designed to be paired with a solar panel system. When your solar panels produce more electricity than you can use in your home, you can store the excess electricity in the battery system instead of sending it back into the grid. Later, when your panels aren't producing enough electricity to meet your home's needs, you can use the stored energy in your battery instead of having to buy it from your utility company.

Pika's original battery solution was designed with two major markets in mind. The first was locations with time-of-use (TOU) electricity rates, such as California, where electricity costs more during the hours of the day when demand is highest, which are often when the sun isn't shining at its brightest. The second was "zero export" markets, such as Hawaii, where solar system owners are prohibited from exporting their excess solar electricity to the grid. The battery has built-in operating modes that are designed to optimize household energy usage under each of these scenarios.

The Generac PWRcell starts at a price of $12,435 and scales up in cost for larger battery models. This price includes the battery itself but not additional costs like installation and labor. The cost of installing a battery isn't as straightforward as looking up the list price for an individual component–i.e., your battery. In fact, depending on your electrical setup, installation costs can vary widely. However, Generac estimates that a 9 kilowatt-hour (kWh) system and installation will cost about $18,000.

If you want to install the PWRcell as part of a solar-plus-storage system, battery costs are just one piece of the equation. A 5 kilowatt (kW) solar energy system costs anywhere from $9,000 to $15,000, depending on where you live and the type of equipment you choose.

That may sound like a lot of money, but installing a solar-plus-storage system can be a worthwhile investment. Whether or not the Generac PWRcell makes sense for you is determined by the way that your electric utility structures its rates, as well as your reasons for installing a solar battery.

In some cases, depending on where you live, you may have access to financial incentives that can reduce your home energy storage installation costs. For instance, if you live in California, you could get a cash rebate that covers most of your home battery costs through the Self-Generation Incentive Program (SGIP). Other states (such as Massachusetts) are in the early stages of evaluating battery storage performance incentives as well, and several states already provide cash rebates.

Generac describes the PWRcell, which first launched in September 2019 following the acquisition of Pika Energy, as a "truly scalable storage system with unmatched raw power." As described in greater depth below, the technical specifications of the battery support these claims: the stackable PWRcell has among the most power of any residential battery currently on the market.

Alongside the PWRcell, Generac offers their own energy monitoring system, known as PWRview. Complete with a custom mobile app, PWRview displays detailed electricity bill tracking and forecasting, as well as other useful energy dashboards. You can also set daily and monthly goals for electricity usage within the application.

When evaluating the PWRcell, there are various important metrics and technical specifications to keep in mind. Among the most important are the size of the battery (power and capacity), its depth of discharge, and roundtrip efficiency.

Size

The Generac PWRcell comes in four different models based on the number of battery modules: the PWRcell M3, PWRcell M4, PWRcell M5, and PWRcell M6. Two important metrics to keep in mind when comparing the PWRcell to other home storage options are power and usable capacity. Power (measured in kilowatts, or kW) determines the maximum amount of electricity that can be output at a single time, while usable capacity (measured in kilowatt-hours, or kWh) is a measure of the maximum amount of electricity stored in your battery on a full charge. The PWRcell M6, the largest battery in the lineup, boasts a maximum off-grid power rating of 9 kW (or 7.6 kW on-grid) to go along with 18 kWh of usable capacity. The M3, M4, and M5 models boast 4.5 kW, 6 kW, and 7.5 kW of maximum off-grid power, respectively.

Importantly, the PWRcell system is modular, meaning that you can add multiple battery products to your storage setup. For example, you might want to install multiple PWRcell batteries for a home with high energy demands. Generac's PWRcell spec sheet indicates that you can connect up to two PWRcells to a single PWRcell inverter, so you'll need to upgrade your supporting hardware to add even more storage capacity beyond the stored energy of two batteries.

Basic functionality

The functionality of one solar battery next to another can vary; some batteries have excellent off-grid capabilities, while others offer software solutions specific to rate arbitrage. Here are some of the most important qualities of the PWRcell:

Chemistry

The PWRcell is a lithium-ion storage product; specifically, it's a lithium nickel manganese cobalt oxide (NMC) battery. Relative to other types of lithium batteries, NMC batteries are known for a relatively high energy density and average power rating – to learn more about how different lithium-ion battery chemistries stack up against one another, check out our overview of battery chemistry differences.

Monitoring

Their monitoring technology is fully built-in to their PWRcell inverter, but Generac also offers their monitoring capabilities with the installation of a device known as PWRview. With the built-in inverter monitoring technology, Generac's PWRcell batteries and their associated parts can intelligently manage electrical loads throughout your house and appropriately pull energy from the battery when needed.

Performance metrics

Two key ways to evaluate the performance of a solar battery are its depth of discharge and roundtrip efficiency.

Depth of discharge (DoD) indicates the percentage of a battery's energy that has been discharged relative to the overall capacity of the battery. Because the useful life of a battery decreases each time you charge, discharge, and re-charge–or cycle–your battery, many battery manufacturers specify a maximum DoD level for optimal battery performance. In general, batteries with a higher depth of discharge are considered better-quality products. The Generac PWRcell boasts a depth of discharge of 84 percent.

Roundtrip efficiency is a measure of electrical losses involved with charging and discharging a battery. The higher the efficiency percentage, the more efficiently the battery is able to convert incoming electricity into stored electricity and then back into usable electricity. The Generac PWRcell DC-coupled batteries have high roundtrip efficiencies of 96.5 percent; this means that for every 10 kWh of electricity you put into the battery, you'll receive 9.65 kWh of output. The PWRcell M6 Battery has a roundtrip efficiency of 90 percent, meaning you'll receive 9.0 kWh of output for every 10 kWh of electricity you put into the battery.

In most cases, homes with a Generac battery will charge and discharge their battery every day. The PWRcell comes with a 10-year limited warranty. For the different models of the PWRcell, Generac also notes a "throughput warranty." A throughput warranty is another way to measure when the warranty period on a battery has been reached based not on time but rather on how much energy has been stored and discharged over its lifetime.

Overall, a PWRcell warranty is valid for either ten years or the amount of time it takes to cycle the specified amount of energy through the battery, whichever comes first. (This is similar to car warranties - ten years or 100,000 miles, where the throughput of a battery is similar to mileage warranties.) The throughput warranty values for each PWRcell model are below:

Importantly, Generac's battery technology is similar to other rechargeable batteries, both large and small: as time goes on, the battery loses some of its ability to hold a charge. Think of how the battery life of a brand-new smartphone compares to one that is a few years old. As you continually charge and drain your phone's battery, it starts to lose some of its ability to hold a charge.

If you want to compare individual battery models side-by-side, our battery Buyer's Guide lets you select products and compare them based on efficiency, capacity, power, and more.

You can (and should) ask many questions about any battery you're installing. Here are a few more quick hits about the Generac PWRcell:

Where can a PWRcell be installed?

Like the Tesla Powerwall, the Generac PWRcell is properly set up to be installed inside or outside.

Can you power an electric vehicle with a PWRcell?

The largest PWRcell model is 18 kWh, which is much smaller than the batteries in most long-range electric cars. As such, you likely won't be able to recharge much of your electric car with a Generac PWRcell.

Can a PWRcell back up your whole house?

In short, yes, but not for long. If you want to back up your whole house for an extended period of time, you'll need a much larger battery bank. Plus, you'll definitely want to pair your storage system with solar panels. A single PWRcell battery might keep your appliances going for a few hours or so, but don't expect to stay powered through a long outage with just a single PWRcell battery (even the biggest one available). Check out our article about how many solar batteries you need to see the math.

The Generac PWRcell battery is currently available online through Generac's website, where you can request a quote and through any solar and/or energy storage installation company that is a certified Generac/Pika installer. Adding energy storage technology to your home is a complicated process that requires electrical expertise, certifications, and knowledge of the best practices required to install a solar-plus-storage system correctly.

A qualified EnergySage-approved company can give you the best recommendation about the Generac home battery system and other energy storage options available to homeowners today. If you are interested in receiving competing installation quotes for solar and energy storage options from local installers near you, simply join the EnergySage Marketplace today and indicate what products you're interested in your profile's preferences section.

Photo courtesy: Generac