Storage systems are becoming increasingly attractive home upgrades for homeowners across the country. Whether you’re looking for self-consumption, rate arbitrage during peak hours, or back-up power in case of emergencies, storage systems can provide greater independence, resiliency, and savings–especially if you have solar panels and live in a state without net metering.
Because storage systems have become so popular, many companies are now in the market, making it more challenging to compare and decide between the different brands and products available. In this article, we’ll explain some of the most important factors for comparing solar batteries and we’ll discuss some of the best brands and products available now.
- Comparing solar batteries can be challenging, but it’s important if you want to find the storage system that best fits your needs.
- Some of the major metrics for comparing solar batteries fall under: chemistry & configuration, power & performance, warranty, and price.
- The top brands and products for solar batteries include: Enphase’s Encharge, Tesla’s Powerwall, Generac’s PWRcell, Panasonic’s EverVolt, sonnen’s eco, LG Chem’s RESU, Electriq Power’s PowerPod 2.
- Visit the EnergySage Marketplace for custom quotes from pre-vetted installers for solar-plus-storage systems.
How to compare solar batteries
There’s a lot to consider when choosing a solar battery! We’ve broken it down into four different categories: chemistry & configuration, power & performance, warranty, and, of course, price. We’ll explain some of the major considerations for each category and then show how the top brands and products stack up. To get a full breakdown of how to choose your battery, check out this article.
Chemistry & configuration
Understanding the different chemistries and configurations available for solar batteries can be difficult, so we’ve outlined some different factors you’ll want to consider before choosing the battery that’s right for you.
- Chemistry: lithium-ion batteries come in various chemistries, but the top batteries on our list are either Lithium Nickel Manganese Cobalt Oxide (NMC) or Lithium Iron Phosphate (LFP). NMC batteries are perhaps the most common solar batteries, but LFP batteries are starting to gain traction because they tend to have higher power ratings and longer lifespans.
- Integrated inverter: batteries can come with or without an integrated inverter. Storage systems without an integrated inverter need to be paired with an external, third-party inverter. Storage systems with an integrated storage inverter are able to convert the usable alternating current (AC) energy from your home to storable direct current (DC) energy, and back again. If your storage system has an integrated hybrid inverter, it can cover both the production from your solar panels and the requirements of your storage system, providing efficient integration for solar-plus-storage systems.
- Coupling: batteries can be either AC- or DC-coupled. AC-coupled storage systems have traditionally been the most common for residential solar systems because they are easy to install, especially if you already have solar panels and are retrofitting your storage system. However, if you’re planning to install a new solar-plus-storage system, installing a DC-coupled storage system may be a better option because it will provide a higher overall efficiency.
- Flexibility of configuration: many battery manufacturers offer different configurations for your storage system so you can size your system according to your needs. Some offer a series of batteries with different capacities and many batteries can be “stacked,” which means that you can add additional batteries to build the storage capacity that you want.
At a glance: chemistry & configuration of best batteries
|Battery||Chemistry||Integrated inverter||Coupling||Flexibility of configuration|
|Enphase Encharge||LFP||Yes - storage||AC||2 different capacity, can stack multiple|
|Tesla Powerwall||NMC||No, unless you get Powerwall+||AC||Can stack up to 6|
|Generac PWRcell||NMC||Yes - hybrid||DC||4 different capacities, can stack up to 2|
|Panasonic EverVolt||NMC||Yes - hybrid||AC or DC||2 different capacities, can stack up to 6 (DC only)|
|sonnen eco||LFP||Yes - storage||AC||7 different capacities|
|LG Chem RESU||NMC||No||AC||Can stack up to 2|
|Electriq Power PowerPod 2||LFP||Yes - hybrid||AC or DC||3 different capacities, can stack up to 3 (AC) or 4 (DC)|
Power & performance
To choose the storage system that meets your needs, you’ll want to compare the power and performance of the different offerings before making a decision. We’ll explain some of the key factors that impact your battery’s power and performance.
- Usable capacity: measured in kilowatt-hours (kWh), usable capacity is a measure of the maximum amount of electricity stored in your battery on a full charge.
- Power rating: measured in kilowatts (kW), a battery’s power rating determines the maximum amount of electricity that can be output at a single time.
- Depth of discharge: the depth of discharge (DoD) indicates the percentage of the battery that has been discharged relative to the overall capacity of the battery. Many battery manufacturers specify a maximum DoD level for optimal battery performance and generally batteries with higher percentages are considered better quality products.
- Roundtrip efficiency: the roundtrip efficiency is a measure of electrical losses involved with charging and discharging a battery. The higher the percentage, the more efficient the battery is at converting incoming electricity into stored electricity, and then back into usable electricity.
At a glance: power & performance of best batteries
|Battery||Usable capacity||Power rating||Depth of discharge||Roundtrip efficiency|
|Enphase Encharge||3.36, 10.08 kWh||1.28, 3.84 kW||100%||89%|
|Tesla Powerwall||14 kWh||5.0 kW||100%||90%|
|Generac PWRcell||9, 12, 15, 18 kWh||3.4, 4.5, 5.6, 6.7 kW||84%||96.5%|
|Panasonic EverVolt||11.4, 17.1 kWh||4.4, 5.5 kW||Not disclosed||84% (AC), 89% (DC)|
|sonnen eco||5, 7.5, 10, 12.5, 15, 17.5, 20 kWh||3, 4, 8 kW||100%||81.6%|
|LG Chem RESU||9.3 kWh||5.0 kW||95%||94.5%|
|Electriq Power PowerPod 2||10, 15, 20 kWh||7.6 kW||Not disclosed||96.6%|
Sifting through warranties for the information you need can be confusing and time-consuming. We’ll discuss some of the key things to look for in battery warranties and assess how the top brands and products compare. Check out this article for more information on solar battery warranties.
- Warranty period: most popular energy storage systems come with a 10-year warranty that covers the integrity and output of your system.
- End of warranty capacity: many manufacturers promise a certain level of performance by the time your warranty term is up. To calculate the warrantied capacity at the end of the warranty term, multiply the end of warranty capacity by the battery’s usable capacity.
- Cycle clause: each time you drain and charge your battery, it’s called a cycle. Each cycle slightly reduces your battery’s ability to hold a full charge–thus, some manufacturers include a cycle clause which means that if you hit your warrantied number of cycles before your battery reaches the end of its warranty period, it could end your warranty term.
- Throughput clause: the throughput clause includes the total energy a manufacturer expects the battery to deliver throughout its lifetime. Stated in terms of megawatt-hours (MWh), these clauses stipulate that if you reach your battery’s throughput before the end of its warranty period, it could end your warranty term. For easy comparison, we’ve stated the throughput clause by kWh of usable capacity. To calculate the total throughput, simply multiply the number we’ve provided by the usable capacity of the battery.
At a glance: warranties of best batteries
|Battery||Warranty period||End of warranty capacity||Cycle clause||Throughput clause|
|Enphase Encharge||10 years||70%||4,000 cycles||N/A|
|Tesla Powerwall||10 years||70%||N/A||2.7 MWh / kWh|
|Generac PWRcell||10 years||N/A||N/A||2.5 MWh / kWh|
|Panasonic EverVolt||10 years||60%||N/A||2.65 MWh / kWh|
|sonnen eco||10 years||70%||10,000 cycles||N/A|
|LG Chem RESU||10 years||60%||N/A||2.4 MWh / kWh|
|Electriq Power PowerPod 2||10 years||70%||N/A||3 MWh / kWh|
Comparing the price of batteries isn’t exactly straightforward. The cost of your battery will vary based on the factors we’ve outlined so far and could reflect the cost of the total installation or just the Manufacturer’s Suggested Retail Price (MSRP). It’s important to assess the price of batteries next to the usable capacity, as this will have the greatest impact on what you pay. You’ll also want to consider the different configurations that are available because it can sometimes be cheaper to stack two smaller batteries than to install one large one.
At a glance: usable capacity vs. price of best batteries
|Enphase Encharge||3.36 & 10.08 kWh||Full installation: $6,000 to $20,000|
|Tesla Powerwall||14 kWh||Full installation: $9,600 to $15,600|
|Generac PWRcell||9 to 18 kWh||Full installation: starting at $9,999|
|Panasonic EverVolt||11.4 & 17.1 kWh||Full installation: $15,000 to $20,000|
|sonnen eco||5 to 20 kWh||Just battery: starting at $10,000|
|LG Chem RESU||9.3 kWh||Full installation: $9,500 to $13,000|
|Electriq Power PowerPod 2||10 to 20 kWh||Just battery: likely more than PowerPod 1, which is $9,799 to $19,999|
Best solar batteries
We evaluated solar battery brands and products based on the metrics described above to create a list of the best solar batteries available today. Each battery comes with different pros and cons: the best storage solution for you may not be the best solution for your neighbor! Be sure to take a look at what we consider to be the highlights of each battery so you can choose a solution that best fits your needs. If you’re interested in learning more about the batteries we’ve included in our list, you can check out our more in-depth reviews of each product, or you can head over to the EnergySage Buyer’s Guide, where you can compare different types of equipment based on efficiencies, warranties, and more.
Highlights: inverter integration, battery chemistry, and DoD.
Enphase is one of the biggest names in inverter technology, but in 2019 it entered into the battery market with the Enphase Encharge. Thus, it’s no surprise that one of the biggest draws of the Encharge is its fully integrated Enphase IQ Series microinverter technology. The Encharge also uses state of the art LFP chemistry, which generally translates to a longer lifespan for your battery and allows for its impressive DoD of 100 percent.
To read our full review of the Enphase Encharge, check out this article.
Highlights: stackability, DoD, warranty, and price.
Tesla has quickly become one of the biggest names in the home energy storage market after launching the Tesla Powerwall in 2015. The Powerwall has a sleek design and is built to be stackable, meaning you can include multiple Powerwalls in your storage setup to increase your usable capacity. Tesla’s Powerwall also boasts a DoD of 100 percent, and Tesla backs up their battery with a competitive 10-year warranty that includes a throughput clause of 37.8 MWh (2.7 MWh / kWh) and a guarantee of 70 percent capacity at the end of the warranty term. The Powerwall also runs at the lower end of the price range for solar batteries.
To read our full review of the Tesla Powerwall, check out this article.
Highlights: roundtrip efficiency and price.
Generac has long been a leader in the backup power space, but recently made its foray into energy storage when it acquired battery manufacturer Pika Energy in 2019 and subsequently launched the Generac PWRcell. The PWRcell has one of the highest roundtrip efficiencies of the batteries on this list at 96.5 percent. It’s also one of the more affordable storage system options available and is best if you’re looking to install solar-plus-storage because it’s a DC-coupled setup, which means higher overall efficiency.
To read our full review of the Generac PWRcell, check out this article.
Highlights: flexibility of configuration.
Panasonic is one of the world’s largest battery cell manufacturers and in 2019, they officially entered the solar battery market with the launch of the EverVolt. The EverVolt is highly configurable, allowing you to design the storage system that fits your needs. It comes in two different capacities–11.4 kWh and 17.1 kWh–which can both be either AC- or DC-coupled. This means that if you already have a solar system, you can easily retrofit the EverVolt with the AC-coupled model, or if you are installing solar-plus-storage, you might want to choose a DC-coupled model, allowing for higher efficiency. With the DC-coupled version, you can also stack up to six EverVolt batteries if you want to maximize your energy storage.
To read our full review of the Panasonic EverVolt, check out this article.
Highlights: battery chemistry, capacity/power, DoD, and warranty.
In 2016, sonnen, one of the most well known companies in energy storage, announced the sonnen eco. The eco uses advanced LFP battery chemistry, which is known for high power ratings and lifespans. The eco doesn’t disappoint: the largest battery in the lineup boasts the largest maximum power of the batteries in this list at 8 kW and one of the largest usable capacities at 20 kWh. It also has an impressive DoD of 100 percent and a competitive 10-year or 10,000 cycles warranty guaranteeing 70 percent capacity at the end of the warranty term.
LG Chem RESU
Highlights: roundtrip efficiency and price.
LG is a huge name in the home electronics industry and their battery subsidiary, LG Chem, produces one of the most popular solar batteries in the U.S. market: the LG Chem RESU 10H. While the RESU is on the smaller end of usable capacity at 9.3 kWh, it includes a high roundtrip efficiency–the highest of the NMC batteries on this list–at 94.5 percent. It’s also one of the most affordable storage systems in the market, starting at around $9,500 for a full installation and can be a great choice if you’re looking for a smaller storage solution.
Electriq Power PowerPod 2
Highlights: flexibility of configuration, chemistry, capacity/power, roundtrip efficiency, and warranty.
In 2021, Electriq Power, a U.S.-based energy storage company, announced an update to their newest product, the PowerPod 2: instead of only offering a DC-coupled system, similar to the Panasonic EverVolt, they now allow you to choose between DC- and AC-coupled versions. The PowerPod 2 comes in three different usable capacities and you can stack up to three of them for the AC-coupled version, or up to four of them for the DC-coupled version. Electriq Power’s PowerPod 2 uses LFP chemistry, allowing the largest battery in their lineup to have one of the highest power ratings of the batteries on this list at 7.6 kWh. This battery also includes one of the highest usable capacities at 20 kWh and the highest roundtrip efficiency of the batteries in this list at 96.6 percent. Electriq Power includes an impressive 10-year warranty to cover the PowerPod 2, with a throughput clause of 3 MWh per kWh, and guarantees 70 percent capacity at the end of the warranty term.
Choosing the best solar battery for your home
The best way to decide on a solar-plus-storage system is to compare multiple quotes. On the EnergySage Marketplace, you’ll receive free, online quotes from pre-vetted installers and free advice from our team of Energy Advisors. Choosing a reliable installer can significantly reduce your risk of encountering battery issues down the line. Interested in a certain battery product? Simply make a note in your profile so installers know to include that product in your quotes.