The best solar batteries of 2021: find the right one for you

Updated

If you’re in the market for a solar battery, you know it can be overwhelming. There are a ton of options, and it’s hard to parse through it all, especially since there is no one-size-fits-all answer when it comes to energy storage. 

The good news is, we’ve picked our favorite residential solar batteries and listed the best uses for each in order to create a buyers guide that helps you find the best solar battery for your home

Editorial note: This is an unbiased review: we have no financial ties with any of the companies mentioned, nor do we earn money from affiliate advertising. The content of this blog is based on research and information available at the time of writing.

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    LG Chem RESU 16H Prime

    Best: Overall battery

    Price: $8,500 (before installation)

    lg chem resu 16h prime solar battery

    LG’s RESU 16H Prime offers a lot of storage at a great price, making it our pick for best overall battery. Image source: SunWatts

    We give LG’s newest battery, the LG Chem RESU 16 H Prime, the title of the best overall solar battery. The RESU Prime has everything you could possibly need in an energy storage system, without costing you an arm and a leg. 

    Table 1. LG Chem RESU 16H Prime specs
    Specification LG Chem RESU 16H Prime
    Usable capacity 16 kWh
    Power rating 7 kW
    Depth of discharge 100%
    Round trip efficiency 97.5%
    Warranty 70% at 10 years or 54 MWh throughput
    Chemistry Nickel Manganese Cobalt (NMC)
    AC or DC-coupled? DC

    Pros: 

    • With a $8,500 price tag, the LG Chem Prime is one of the cheapest storage options of its size
    • 16 kWh of useable capacity means you can store more than the average home’s daily electrical usage
    • DC-coupling makes the battery more efficient than other batteries on the market, maximizing the amount of solar energy your home can use
    • Most installers are familiar with the brand, making the batteries more widely available and installations a bit easier

    Cons:

    • Warranty isn’t as impressive as compared to other batteries, however, because the starting capacity of the LG Chem Prime is so high, the battery will still hold a substantial amount of energy once the warranty period is over
    • Nickel manganese cobalt (NMC) chemistry means that the LG Chem RESU Prime is more susceptible to catching fire when mishandled than other batteries, but the chances of this happening are extremely low as long as the battery is properly installed
    • Cobalt within the battery makes the LG RESU Prime harder to recycle at the end of its life
    • DC-coupling makes it more difficult to pair an LG battery with an existing solar panel system; it can still be done, so long as the installer is willing to do the work, but it will increase the installation price

    Tesla Powerwall

    Best: Nickel manganese cobalt (NMC) battery 

    Price: $8,500 (before installation)

    tesla powerwall plus

    The Tesla Powerwall nickel manganese cobalt battery comes with an excellent warranty and easy-to-use operating modes. Image source: Tesla

    Perhaps the most well-known solar battery on the market is the Tesla Powerwall, and for good reason. The Powerwall is a great NMC battery with excellent monitoring features.

    However, some of Tesla’s recent decisions regarding the sale of Powerwalls makes them more difficult to get, and therefore less desirable for consumers, especially those who already have solar panels on their roof (that’s because you can only buy a Powerwall along with the purchase of a Tesla solar power system or solar roof).

    Table 2. Tesla Powerwall specs
    Specification Tesla Powerwall
    Usable capacity 13.5 kWh
    Power rating 5.8 kW - 9.6 kW, depending on conditions
    Depth of discharge 100%
    Round trip efficiency 90%
    Warranty 70% at 10 years, unlimited cycles
    Chemistry Nickel Manganese Cobalt (NMC)
    AC or DC-coupled? AC

    Pros:

    • AC-coupling means the Powerwall can easily be integrated into existing solar panel systems
    • Excellent warranty with unlimited cycles
    • Rated to perform better than other batteries in lower temperatures and at higher altitudes
    • Has three operating modes: Backup Power, Solar Self Consumption, and Time-of-Use load shifting, to ensure the battery meets your needs
    • Higher-than-average power output means the battery can handle powering more appliances in your home when the grid is down

    Cons:

    • Production delays, equipment shortages, and a backlog of orders means you could wait upwards of a year to get a Powerwall installed
    • Tesla does not sell Powerwalls for individual sale, they must be paired with a new Tesla solar system. Powerwalls can be purchased individually fom Tesla-certified installers, but usually the wait will be longer. Overall, Powerwalls are hard to get your hands on
    • Because it can be difficult to purchase an individual Powerwall without a new solar system, it doesn’t really matter that the Powerwall is an AC battery because it’s unlikely you’ll find one to pair with an existing system
    • NMC chemistry means it’s more susceptible to catching fire if mishandled and is harder to recycle 
    See what local Tesla-certified installers are charging in your area

    Electriq PowerPod2 10 kWh

    Best: Lithium iron phosphate (LFP) battery

    Price: ~$10,000 (before installation)

    Electriq PowerPod2 10 kWh solar battery

    With multiple models and configurations, the Electriq PowerPod 2 gets our vote for best lithium iron phosphate battery. Image source: Electriq Power

    Released by Electriq in November 2020, the PowerPod 2 is the battery manufacturer's newest product. Although there are plenty of great LFP batteries on the market, we give the title of best LFP to the PowerPod 2 because it comes in both AC and DC models, making it easy to pair with both new and existing solar systems. The PowerPod 2 also comes in a variety of sizes, so you can find the capacity that best fits your energy needs. 

    Table 3. Electriq PowerPod 2 10 kWh specs
    Specification Electriq PowerPod 2 10 kWh
    Usable capacity 10 kWh
    Power rating 7.6 kW
    Depth of discharge Not listed
    Round trip efficiency 96.6%
    Warranty 70% at 10 years or 7.5 MWh throughput per module
    Chemistry Lithium Iron Phosphate (LFP)
    AC or DC-coupled? Both

    Pros:

    • The PowerPod 2 does not contain cobalt, so it can be more easily recycled at the end of its life
    • The LFP chemistry allows the battery to operate at higher temperatures with a lower risk of catching fire
    • The Electriq PowerPod 2 has both AC and DC-coupled models, so it can be installed with new or existing solar panel systems
    • Sizes range from 10 kWh to 20 kWh, giving you flexibility when it comes to choosing a battery
    • In addition to the standard Backup, Self Supply, and Time-of-Use operating modes, Electriq also offers a custom mode with its AC models, so you can set a schedule for how your battery operates based on your lifestyle  

    Cons: 

    • If each of the individual battery packs was completely drained every day, you would reach the warranty throughput threshold before you reach 10 years; however, many homeowners won’t cycle through their battery this often
    • The price, though not explicitly listed anywhere, is estimated to be a bit higher than some of their competitors. Keep in mind, prices can vary greatly depending on the system needs, and the price does include an inverter
    • Electriq is a smaller brand than some others on the list, so there could be limited availability 

    sonnenCore

    Best: AC-coupled battery

    Price: $9,500 (before installation)

    sonnencore solar battery in a garage

    The sonnenCore battery can be easily added to existing solar systems, plus it has high safety ratings. Image source: Solaflect Energy

    The sonnenCore is the newest and most affordable battery from German manufacturer sonnen. We’ve rated the sonnenCore the best AC-coupled system because, unlike the Powerwall, you don’t have to jump through hoops to purchase one. So, if you already have solar panels and you want to add a solar battery, the sonnenCore is a great choice. 

    Table 4. sonnenCore specs
    Specification sonnenCore
    Usable capacity 10 kWh
    Power rating 4.8 kW
    Depth of discharge 100%
    Round trip efficiency >85%
    Warranty 70% at 10 years or 58 MWh throughput
    Chemistry Lithium Iron Phosphate (LFP)
    AC or DC-coupled? AC

    Pros:

    • AC-coupling makes it easy to pair the sonnenCore with an existing solar panel system
    • The sonnenCore’s LFP chemistry does not contain cobalt, so it’s stable at higher temperatures and reduces the risk of catching fire
    • The warranty for the sonnenCore is great - estimating 58 megawatt-hours (MWh) of throughput before the battery will drop to 70% capacity
    • 10 kWh of capacity is the perfect size for most residential uses
    • Three operating modes allow you to choose how your battery charges and discharges to meet your exact power needs 

    Cons:

    • The sonnenCore costs $9,500 before installation, making it one of the more expensive lithium ion battery options
    • Because the sonnenCore is a newer battery, and sonnen’s older models were considered luxury, it may be hard to find an installer familiar with the brand in your area
    • The sonnenCore has a power rating that is slightly below industry standards, meaning that it can’t release as much power to your appliances
    • Because the sonnenCore is an AC battery, it has a lower round trip efficiency rating, which means that you store less of the solar energy you’re producing 

    BYD Battery-Box HVS 10.24 kWh

    Best: DC-coupled battery

    Price: $7,500 (before installation) 

    10.2 kWh BYD B-Box HV Battery Storage w/6kW SMA Sunny Boy Storage InverterThe modular design of the BYD-Battery Box makes it easy to add more storage to your solar system in the future. Image source: SunWatts

    BYD, an abbreviation for “Build Your Dreams”, is a Chinese-based manufacturing company that works in not only the energy storage industry, but also the electric vehicle, rail, and electronics industries. Their Battery-Box residential batteries utilize lithium iron phosphate chemistry, making them more stable, and thus safer, than many other batteries on the market. 

    What makes the BYD Battery-Box stand out from the others is its modular design, meaning you can easily add more battery packs in the future. This takes the sting out of the main drawback of DC batteries, which is that they can be difficult to pair with existing solar systems. The BYD Battery-Box lets you start small if you're unsure about storage, and add more battery packs later on if you need. 

    Table 5. BYD Battery-Box HVS 10.24 kWh specs
    Specification BYD Battery-Box HVS 10.24 kWh
    Usable capacity 10.24 kWh
    Power rating 10.24 kW 
    Depth of discharge 100%
    Round trip efficiency ≥ 96%
    Warranty 80% at 10 years or 24.96 MWh throughput
    Chemistry Lithium Iron Phosphate (LFP)
    AC or DC-coupled? DC

    Pros:

    • Because the Battery-Box does not contain cobalt, it is less susceptible to catching fire and can be more easily recycled at the end of its life
    • Low price for an LFP battery
    • The Battery-Box’s modular design makes it easy to expand the system if you need more storage, with a maximum system size of 38.4 kWh
    • DC-coupling means it has a high efficiency rating
    • The Battery-Box has three operating modes so you can easily choose how you want the battery to operate
    • Can be installed with both grid-connected and off-grid systems
    • BYD offers Battery-Box models with different voltage capabilities, so you can choose which battery is right for your system

    Cons:

    • The Battery-Box warranty falls short of industry standards, operating at only 60% of its original capacity after 10 years or after 30.82 MWh of throughput, which is low compared to other batteries on the market
    • Can be difficult to pair with existing solar systems because it is a DC battery
    • The BYD website is quite difficult to navigate, making it next to impossible to find information about these batteries

    Generac PWRCell 9 kWh

    Best: Modular battery

    Price: $9,999 (before installation)

    Generac PWRCell 9 kWh solar battery

    Generac’s solar battery capacity can be expanded in the future. Image source: Norwall Power Systems

    Generac is best known for their gas-powered generators, but they offer a solar energy storage system, too. The Generac PWRCell is great because it’s modular - meaning it contains many small battery packs. Having small, 3 kWh battery packs means you can easily customize the size of the battery to up to 36 kWh of storage.

    There are a few other modular batteries on this list, but we put the Generac version as the number one because it is so easy to install and is widely available.

    Table 6. Generac PWRCell specs
    Specification Generac PWRCell
    Usable capacity 9 kWh
    Power rating 4.5 kW
    Depth of discharge 100%
    Round trip efficiency 96.5%
    Warranty 70% at 10 years or 7.56 MWh throughput per module
    Chemistry Nickel Manganese Cobalt (NMC)
    AC or DC-coupled? DC

    Pros:

    • Even though it’s a DC battery, the modular nature of the PWRCell makes it easy to expand your energy storage system if you find you need more energy storage after it’s installed
    • Generac is a well-known and successful brand so you can trust that they’ll be around for a while to honor their warranty
    • All PWRCell installations come with a battery cabinet, the battery modules, and an inverter designed specifically to pair with their products

    Cons:

    • The PWRCell contains cobalt, so it can be difficult to recycle and it is more susceptible to catching on fire if mishandled
    • If each of the individual battery packs was completely drained every day, you would reach the warranty throughput threshold before you reach 10 years; however, many homeowners won’t cycle through their battery this often
    • Because it’s a DC battery, it can be difficult to add a PWRCell to an existing solar system
    • The power rating of the PWRCell is lower than industry standards, so it can’t supply as much power as other batteries
    • The price is a little high compared to batteries with similar specifications
    Is installing battery storage worth it in your area?

    What to look for in a solar battery

    Our list for the best solar batteries doesn’t cover all of the energy storage options out there. To find the best solar battery for your specific energy needs, you should look at a few different factors. 

    1. Battery capacity 

    The capacity rating of a battery indicates how much solar energy it can store, measured in kWh. The higher the battery capacity, the longer the battery will be able to power your appliances. The battery capacity that’s right for you depends on your energy usage and what you plan to use the battery for

    In most cases, somewhere between 9 kWh and 15 kWh of capacity will suffice. If you use a lot of electricity, you may need more than that, but that can cost you quite a bit of money. If you’re not sure how much electricity you want to store, then consider a modular battery like the Generac PWRCell or the BYD Battery-Box, as they give some level of flexibility when it comes to installing more storage later on. 

    2. Power rating 

    The power rating of a battery tells you how much power the battery can release for your home to use. Batteries with high power ratings can run more appliances at once. The Tesla Powerwall has one of the best power ratings for a residential solar battery. 

    You want to make sure you look at the battery capacity and the power rating together to make sure a battery will meet your needs. A battery with a high power rating and a low capacity will be able to power more appliances for a short amount of time, whereas a battery with a larger capacity and a lower power rating will power fewer appliances for an extended period. 

    Most homes will be able to power their main loads, like their fridge, WiFi, lights, and outlets during an extended power outage with a battery that has a 5 kW power rating and 10 kWh capacity rating. 

    3. AC or DC-coupled 

    Batteries can either be AC-coupled or DC-coupled. As a rule of thumb, AC batteries are better for pairing with existing solar panel systems because they have their own inverter. DC batteries are best for installing at the same time as solar panels

    AC batteries tend to be less efficient than DC batteries because the electricity produced by the solar panels is converted from DC to AC power more times than it is with DC batteries. 

    You can read our complete guide to AC and DC batteries here to get a better idea of their pros and cons, as well as which is right for your home. 

    4. Warranty 

    One of the best ways to compare batteries is by looking at their warranties. Battery warranties give you an idea of how long the battery will last. 

    Most batteries have a production warranty of 70% capacity after 10 years, or after a certain number of cycles, whichever comes first. A cycle is how many times the battery will be completely charged and discharged, based on the recommended depth of discharge (most lithium ion batteries today have a DoD of 100%). 

    A warranty may also list a throughput measurement, which is how much electricity the battery will discharge before the capacity reaches 70%. Ideally, you want to go with a battery that has the highest warrantied throughput, as it will last the longest

    5. Chemistry 

    Most solar batteries today are lithium ion batteries, which can be divided into two main categories: lithium iron phosphate (LFP) and nickel manganese cobalt (NMC).

    NMC lithium ion batteries have been around longer than LFP batteries, and make up a majority of the lithium ion battery market share. The biggest downside to NMC batteries is that they aren’t as stable at high temperatures, making them more susceptible to catching fire if they’re mishandled. Also, the cobalt within the battery makes it difficult to recycle at the end of the battery’s life. 

    Not only that, LFP batteries are a newer addition to the solar battery market, so they can be slightly more expensive than NMC options. However, because LFP batteries don’t contain cobalt, they are less likely to catch fire and can operate at higher temperatures than NMC batteries. 

    Is a solar battery right for you?

    We’re going to be honest: in most cases, solar batteries don’t make financial sense, especially if you live in an area with full-retail net metering. Batteries add quite a bit onto your upfront costs, and they won’t save you that much extra money. In fact, in many cases, batteries add no additional financial savings. 

    So, why get a solar battery? For many people, the appeal of solar batteries isn’t financial, it’s about energy resilience. Solar batteries ensure you keep your lights on and your solar panels running during a power outage, making them more worthwhile for those who live in areas that experience frequent prolonged power outages. 

    While solar batteries won’t always give you great savings, solar panels will. Solar panels provide significant electric bill savings in almost every state in the U.S. By using our solar panel calculator, you can find out how much a solar panel system will cost and save you, based on just your most recent electric bill. 

    Get a custom cost and savings solar estimate for your specific home
     - Author of Solar Reviews

    Catherine Lane

    SolarReviews Blog Author

    Catherine is a researcher and content specialist at SolarReviews. She has strong interests in issues related to climate and sustainability which led her to pursue a degree in environmental science at Ramapo College of New Jersey.

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