Generac Pwrcell Review: A Modular Solar Battery

7.2

Generac Pwrcell

Like

• Modular design
• Higher efficiency
• Options for customer support

Don't like

• Lower depth of discharge
• Lower power output (at smaller capacity sizes)

Solar panels are gaining popularity for many reasons, but they won't help you in a blackout. You'll need a home battery system for that. Just like solar panels, that battery will need to meet the particular needs of your home -- they aren't one size fits all.

The Generac Pwrcell was released in 2019 and has since become one of the most recognizable batteries in the solar industry. This solar battery was designed to make it easy for homeowners to get the exact battery capacity that they need for their home's energy needs.

"The thinking behind the battery and surrounding energy storage was that not all homes are created equal," Rex Liu, Generac's vice president of product management, told CNET. "The needs of every homeowner could be very different, so having a modular battery was something that could bring a lot of value to the market overall. An installer can optimize the solution for their particular homeowner customer."

Solar batteries are big, bulky, expensive and part of a holistic home energy system. That makes them difficult to put through hands-on testing. This review is based on specs and information provided by Generac online and an interview with Liu to get the most accurate and up-to-date information. 

Here's what you should know about the Generac Pwrcell.

What do I get with the Generac Pwrcell?

The Generac Pwrcell is one of the most modular batteries we've seen. In our review of the best solar batteries, the Pwrcell stood out in its modularity, capacity sizes, efficiency and performance. Here's a quick look at the Generac Pwrcell's specs.

System components

The Generac Pwrcell is more than just a battery box that sits in your garage or hangs on the wall. It's an intricate, DC-coupled system with quite a few components. Here's a quick breakdown of the Pwrcell system:

Battery cabinet: The Pwrcell stores energy a bit differently compared with other solar batteries. Instead of a battery box, the Pwrcell system has a battery cabinet, which houses several lithium-ion battery modules. The battery cabinet houses three to six battery modules. The number of battery modules in the cabinet reflects the storage capacity available. A second battery cabinet can be installed for additional capacity. 

Inverter: The main function of the inverter is to convert DC energy from the solar panels and battery into AC energy to power your home. Since the Pwrcell is a DC-coupled system, you'll have to use the Generac inverter that is provided with the Pwrcell. 

Automatic transfer switch: The ATS provides an automatic transition to back up battery power in a power outage. 

PV link: This helps optimize how power is generated by your solar panels and stored in the battery. It also works with a rapid shutdown device connected to the solar panels.

Capacity and modularity

The capacity and modularity categories are where the Pwrcell shines the brightest, scoring as the most modular battery on our rankings of the best solar batteries. The Pwrcell stores energy in individual battery modules contained within a battery cabinet. One battery cabinet holds between 9 kWh and 18 kWh of energy, with capacity expandable in increments of 3 kWh. This design allows homeowners easier access to the capacity size that is "just right" for their home's energy needs. 

Upgrading the Pwrcell's capacity is easy. Instead of buying a whole new battery, you'll just purchase a new battery module. You'll have to hire an installer to insert the new battery module. Once you hit the maximum capacity (18 kWh), you'll need to install an additional battery cabinet. You can have up to two battery cabinets, for a maximum capacity of 36 kWh. 

Performance and efficiency

 The Pwrcell has a higher-than-average round-trip efficiency of 96.5%. This means only 3.5% of your electricity gets lost on its way to battery storage. The average round-trip efficiency of the lithium-ion batteries currently on the market is about 90%. 

However, the Generac Pwrcell's depth of discharge is the lowest we've seen for lithium-ion solar batteries, at 84%. A battery's depth of discharge is a limitation set by the manufacturer on the amount of energy that can be drained all at once without damaging the battery. The average depth of discharge for a lithium-ion solar battery is about 94%. 

The Pwrcell performs well in the power output category at larger capacities. At smaller capacities, it's a lot weaker. The higher the installed capacity, the higher the power output.

If you're looking for a smaller battery but don't want to sacrifice power, there are better options than the Pwrcell. It has an on-grid peak power output of 4.5 kW - 9 kW and an on-grid continuous power output of 3.4 kW - 7.6 kW. 

A battery's peak power output rating is the maximum amount of power it can output all at once, and is normally used when large appliances or power loads kick on. A battery's continuous power output is the amount of power the battery can handle all the time.

Warranty

How's the Pwrcell's warranty? It's pretty much the industry average, which isn't a bad thing. But if your main consideration when shopping for a battery is the warranty, there are much better options available. Here's an overview of the Pwrcell's warranty. 

Years covered: This is the length of time your battery is covered under warranty. The Pwrcell comes with a 10-year warranty, which is the industry standard.

Throughput: This is the manufacturer's estimate on the total amount of energy the battery is expected to supply throughout its lifetime, measured in megawatt-hours. Since this is a modular battery, each individual battery module has its own aggregate throughput. Generac expects each battery module to deliver 7.56 MWh of energy during its lifetime. Be aware that once a module hits its throughput (7.56 MWh), it is no longer covered under warranty. 

End-of-warranty capacity guarantee: Your battery's overall capacity will start to deteriorate over time. Generac guarantees that each battery module will be able to hold at least 70% of its maximum energy capacity by the time your warranty expires. This is the industry standard.

Customer support

Need help with your battery system? The first person to call is your installer. Since they'll be able to physically visit the installation site, they'll likely be the most helpful. Your installer is also more familiar with your specific battery system. But if you can't reach your installer, Generac provides several ways you can contact them for customer support.

Generac is one of the few battery manufacturers we've seen that offers a 24-hour support phone line. If you don't feel comfortable getting on the phone immediately, you can fill out an online form for support and wait for someone to contact you. Generac also has an online FAQ library to help you assist you as well.

Generac PWRview app

The Generac Pwrcell is compatible with Generac's well-rated energy management app – PWRview. The PWRview app monitors your solar production, shows your battery's state of charge and tells you when you're drawing power from the grid and when you're feeding power to the grid. The app also keeps track of your historical energy data to help calculate estimated savings. 

How much does the Generac Pwrcell cost?

The Generac Pwrcell is estimated to cost between $10,000 and $20,000 before installation. Cost is reflective of how many battery modules you have installed: The higher your battery capacity, the higher the price tag. Other factors affecting price are location, the installer and the amount of solar on your roof. As a rule of thumb regarding battery pricing, you can usually expect to pay between $1,000 and $2,000 per kWh of energy storage.

For the most accurate pricing, you'll need to speak with a Generac Pwrcell-certified installer in your area. We recommend gathering a few quotes from national and local installers to see who will give you the best price possible. 

Is the Generac Pwrcell my best choice?

It depends on what you're looking for in a battery and what your energy storage goals are. In terms of its technical specs, the Pwrcell is a decent battery, excelling in modularity, capacity and efficiency. But don't limit your options to just the Pwrcell. Explore multiple battery storage options on your own or with an installer. Most installers are certified to install multiple brands of batteries, so don't feel like you only have one option. 

Read more: Want something smaller than a whole-home solar system? See our picks for the best portable solar panels and solar generators.

How we evaluated the best solar batteries

First let's be clear: Not every solar battery is right for every home. Solar is a very site-specific and personalized decision process, so it's a little tricky to pinpoint exactly which solar battery is the "best" battery for your home's energy needs without doing an on-site consultation. 

It should also be said that we didn't have any form of hands-on testing with any of the batteries we scored. This methodology also assumes you're purchasing a battery for the main purpose of using it for energy backup. If you mainly plan to use your battery for energy offset or to take part in a virtual power plant, there are likely better options than what we have featured in our reviews and rankings. We strongly encourage you to do your own research, as well as to speak with installers in your area. An installer will be able to get a better understanding of your home's energy use and what sort of system you might need. 

We used a few ways to evaluate and compare these batteries to find the stand-outs. Here's how we developed our list of top solar batteries.

First, we determined which categories would be used to evaluate each battery's performance, capacity and value. We also weighted each category. The weight of each category reflects the importance we felt was relevant to the average consumer: 

• Modularity: 20%
• Warranty: 20%
  
• Round-trip efficiency: 15%
  
• Power output: 15%
  
• Depth of discharge: 10%
  
• Price: 5%
  
• Price transparency: 5% 
  
• Customer support options: 10%
  

We looked at more than 15 of the most widely available batteries on the market and collected the data for each category to compare the numbers. Each category (for every battery) was given a rating (from 1 to 5) to evaluate which aspects of each battery were above average (among our list), just average or below average.

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