GENERAC PWRCELL

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.

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 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. Find out what solar costs in your area in 2020.

KEY THINGS TO KNOW ABOUT THE GENERAC PWRCELL

29.6" / 753 mm

5.75" / 147 mm

45.3" / 1150 mm

HOW DOES THE GENERAC PWRCELL WORK?

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 on 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
 

TECHNICAL SPECS

Usable Capacity                        

6.7 kw to 17.1 kWh 

Depth of Discharge

84%

Efficiency

96.50% round-trip

REbus Voltage

Input /Output

360-420 VDC

Module Voltage

46.8 VDC

Recommended Ambient

46.8 VDC

Communication Protocol

REbus, DC Nanogrid

Operating Temperature             41°F to 113°F / 5°C to 45°C

Recommended Ambient Temperature

55°F to 86°F / 13°C to 30°C

Dimensions

L x W x H: 22" x 10" x 68" Inch

(559 x 254 x 1727) mm

Weight, Enclosure LB (KG)

115 (52)

Maximum Installation Altitude

9834 FT (3000 M)

Warranty LI-ON Modules

10 years, (7.56 MWh)

Size

The Generac PWRcell comes in four different models: the PWRcell 9, PWRcell 12, PWRcell 15, and PWRcell 17. 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 17, the largest battery in the lineup, boasts a maximum power rating of 6.7 kW to go along with 17.1 kWh of usable capacity. 

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.

Think of your battery like water running through a pipe. The usable energy capacity is the amount of water available to push through the pipe, while power is the size of the pipe itself. Larger pipes allow more water to flow through at once, which depletes the water faster. Similarly, a battery with a high power rating can deliver more electricity at one time, but will burn through its available energy capacity faster too.

A battery’s power determines the number of appliances you can run from the battery concurrently, while usable capacity determines how long those appliances can be run. Batteries with a higher power rating are capable of powering more, bigger appliances (i.e., your HVAC system) or many appliances at once, while batteries with a higher usable capacity can store more total energy and thus can run your appliances for longer periods of time without needing to recharge.


 

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. The suite of PWRcell hardware and software products are designed to provide both of these services.

Generac offers a solar inverter alongside their PWRcell. This inverter acts as both a battery inverter and a rooftop solar array inverter. This means that, as long as your installer installs the correct components and the PWRcell inverter, your Generac PWRcell battery will be able to provide backup power for your home when the grid goes down, as well as interact with your solar panel system if you have one.

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 has a high roundtrip efficiency of 96.5 percent; this means that for every 10 kilowatt-hours (kWh) of electricity you put into the battery, you’ll receive 9.65 kWh of output.

Generac PWRcell warranty coverage

Generac PWRcell warranties

  • Warranty period: 10 years 

  • Throughput warranty: between 22.6 and 45.3 megawatt-hours (MWh), depending on battery size

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 10 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.)

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.
Warranty, capacity, and power are three of the most important metrics you should consider when comparing home battery options.


 

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