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In this article: Best Solar Batteries | Types of Solar Batteries | How To Choose a Battery | The Bottom Line | FAQs | Methodology

Solar batteries store excess energy your solar panels produce to use at night, on cloudy days or during power outages. Adding them to your system allows you to use more of the solar energy you’re creating, reducing overall energy costs and maximizing your savings.

We at the Home Media reviews team have researched dozens of solar batteries from the best solar companies in the industry. This guide compares the top seven brands.

Below are our top seven solar batteries:

The Tesla Powerwall 2 is one of the most popular solar batteries. It’s an AC lithium-ion battery that can be retrofitted into any existing solar power system. It also has one of the best warranties of the batteries we reviewed, with a standard 10-year warranty and an unlimited cycle clause. 

Here are the pros and cons of the Tesla Powerwall 2:

+ Can be retrofitted into existing solar systems

+ Guaranteed 70% capacity at the end of the warranty

– Can’t be purchased directly from Tesla

– Comes in only one size 

The Tesla Powerwall 2 offers a usable capacity of 13.5 kWh. It’s not modular — meaning it only comes in one size — but you can stack multiple batteries to meet your power needs. The battery has a continuous power rating of 5 kW, the industry standard. This measurement represents the amount of electricity that it can produce consistently.

The Powerwall 2 has a round-trip efficiency of 90%, meaning you can use 90% of the battery’s stored energy. The other 10% is lost during the energy storage process. 

The Powerwall 2 has a depth of discharge (DoD) of 100%. This means they can be charged up to 100% of their usable capacity . Many manufacturers limit DoD because fully draining a battery of its capacity shortens its lifespan, b ut the Powerwall 2 can charge to its maximum capacity without affecting its lifespan.

The Powerwall 2 has a 10-year warranty with a guaranteed end-of-warranty capacity of 70%. It also has an unlimited cycle clause and no throughput clause, meaning the battery is covered for the entire term regardless of how many cycles it completes or how much energy it produces.

A cycle clause limits the number of times your battery can drain and recharge, called a charging cycle. This clause can end your warranty early if your battery completes its guaranteed cycles before the end of the term. A throughput clause measures the total potential energy generated in the battery’s lifetime. It can also end your warranty early if your battery reaches this threshold before the end of the term.

You can’t buy the Tesla Powerwall 2 directly from Tesla without buying a new solar panel or solar roof system. You can buy the battery separately from third-party suppliers or solar companies.

The Sonnen Eco is a modular battery with seven size options. Its advanced Lithium Iron Phosphate (LFP) technology gives it a longer lifespan and improved efficiency compared to competitors.

Here are the Sonnen Eco battery’s key details: 

+ Improved power rating and lifespan from advanced LFP technology

+ Seven battery sizes for customized builds

+ 10-year warranty and 10,000 cycle clause

– Heavier than other batteries 

– Not as compact as other batteries  

The Sonnen Eco offers more battery sizes than any manufacturer on our list, making it easier to fit the power output of your solar panel system. Options range from 2.5 kWh modules that can combine to form a small system of 5 kWh to a high-capacity 20 kWh module. Sonnen offers the following battery models:

Sonnen Eco batteries have a DoD of 90% and a round-trip efficiency of 81.6% for all sizes. These batteries are larger and heavier than other solar batteries, ranging from 394 pounds for the smallest battery to 830 pounds for the Eco 20.

Sonnen provides a 10-year warranty with a guaranteed end-of-warranty capacity of 70%. Its battery has a 10,000 cycle clause, much higher than the typical 4,000 to 6,000 range.

Sonnen Eco batteries are available through Sonnen-certified partners and installers in the United States.

Enphase is known for its high-quality inverters. Its solar battery, the Enphase IQ (formerly known as the Enphase Encharge), is integrated with this technology. The battery works with existing solar systems and provides software with insight into your power usage. 

Here are the Enphase IQ’s key features:

+ Can connect to a gas-powered or solar generator 

+ Includes two battery sizes for existing solar systems 

+ Offers an optional five-year warranty extension  

– Designed to work with systems with Enphase inverters 

– Has a lower cycle clause than other batteries in our review 

Enphase offers modular solar batteries in the following four models:

You can customize your storage system by combining the 3/3T and 10/10T models. The 3/3T models have a continuous power rating of only 1.28 kW, and the 10/10T versions have 3.84 kW. All Enphase IQ models have a round-trip efficiency of 96% and a DoD of 100%. They’re LFP batteries, which are safer than Lithium Nickel Manganese Cobalt Oxide (NMC) models and have a longer lifespan.

All four batteries include a 10-year warranty and an industry-standard 4,000 cycle clause. These warranties include a throughput clause of 9.8 megawatt-hours (MWh) for the IQ 3 models and 29.4 MWh for the IQ 10 options. All four models have a guaranteed end-of-warranty capacity of 70%. 

These batteries are made to work with Enphase inverters. Enphase IQ batteries are available through the Enphase sales team, online shop or solar panel installers.

The Generac PWRcell is a modular, DC-coupled battery with one of the highest round-trip efficiencies on our list at 96.5%. It is an excellent option for new solar systems. 

Here are the advantages and disadvantages of the Generac PWRcell: 

+ Has one of the highest round-trip efficiencies of any battery on our list

+ Includes a protective battery cabinet for indoor or outdoor installation

+ Offers small modular battery options 

– Contains cobalt, which is hard to recycle

– Is difficult to install on an existing solar power system 

The Generac PWRcell is one of the few modular DC-coupled batteries on our list. You’ll need to get a separate inverter, unlike AC-coupled batteries that include them. The Generac PWRcell uses NMC technology, the most common type of solar battery storage available. However, NMC batteries are difficult to recycle because they contain cobalt. They’re also more susceptible to fires when misused.

Generac customers can choose from four different system capacities. Each system is built with modules of 3 kWh.

The PWRcell battery has a round-trip efficiency of 96.5%. Its DoD is 84%, which is lower than many of the batteries on this list.

The Generac PWRcell includes a 10-year warranty with throughput clauses that vary between modules. Your warranty’s conclusion depends on which threshold you reach first: the throughput clause or the official warranty end date. Here’s a breakdown of the throughput clauses by model:

Generac PWRcell is available on the company’s website or through certified Generac-certified installers and solar companies.

The LG Chem RESU-10H is a popular solar battery backed by one of the most respected electronics companies in the world. It works with existing solar systems and can be stacked for added storage options. The LG RESU-10H also has one of the highest round-trip capacities for an NMC battery at 94.5%.

We’ve listed the pros and cons of the LG Chem RESU-10H below:

+ Has one of the highest NMC round-trip efficiencies on our list

+ Is a great option for homeowners with lower energy needs 

+ Is one of the most widely used solar batteries

– Guarantees a 60% end-of-warranty capacity, one of the lowest on our list

– Lower throughput clause could end the warranty early

The LG Chem RESU-10H is a good option for homes with lower energy needs. It has a usable capacity of 9.8 kWh, which is on the smaller end of the batteries we reviewed. Customers can add multiple batteries for increased storage capacity up to 32 kWh. The battery has a continuous power rating of 5 kW.

The LG Chem RESU-10H has a round-trip efficiency of 94.5%, one of the highest for NMC batteries we reviewed. It has a DoD of 90%.

LG Chem’s warranty is a little disappointing compared to other batteries. Though the company offers an industry-standard 10-year warranty, there’s a low throughput clause of 22.4 MWh. The battery has a 60% end-of-warranty capacity guarantee, which is standard but lower than other batteries on this list.

The LG Chem RESU-10H is available through LG’s network of licensed installers.

Known for its high-efficiency solar panels, SunPower developed a solar battery in 2019. It’s one of the highest capacity batteries on this list and uses the latest LFP battery chemistry, making it more powerful and long-lasting.

Here are the pros and cons of the SunPower SunVault:

+ Boasts one of the largest usable capacities on our list 

+ Offers two battery options for more customization 

+ Uses LFP technology for longer battery life and improved safety

– Doesn’t provide depth of discharge information 

– Only works with SunPower solar panel systems

SunPower provides two battery options: the SunVault Storage 13 with 12 kWh capacity and the SunVault Storage 26 with 24 kWh. The 26 model has one of the largest usable capacities of the batteries we reviewed and an above-average continuous power capacity of 6.8 kW.

Unfortunately, SunPower doesn’t disclose DoD information. Both batteries have a round-trip efficiency of 85%, the second-lowest in this review.

SunPower backs its solar batteries with a standard 10-year warranty. The SunVault Storage 13 battery has a 38 MWh throughput clause and a 4,000 cycle clause. The SunVault Storage 26 also has a 4,000 cycle clause but increases the throughput clause to 76 MWh. Both batteries are guaranteed a 70% end-of-warranty capacity. 

SunVault systems are exclusive to SunPower solar panel systems. You can only get them through SunPower or its network of authorized dealers. 

To learn more: SunPower Review

Panasonic has a history as a leading battery manufacturer. The company’s solar battery, Panasonic EverVolt, offers AC- or DC-coupling options. You can install the batteries in an existing solar panel system or add them to a new one.

Here are the key features of Panasonic EverVolt:

+ Made by the world’s leading battery manufacturer

+ Offers options for new or existing solar panel systems

+ Has four models that stack for a higher total capacity

– Doesn’t provide depth of discharge information 

– Promises a low 60% end-of-warranty capacity 

The Panasonic EverVault systems offer AC and DC models that can be stacked for improved total capacity. Here’s a breakdown of the four models:

According to Panasonic, its standard batteries provide an average of six hours of backup power, while the Plus options offer nine hours. The standard models have a continuous power rating of 4.6 kW. and the Plus options rate higher at 5.5 kW. 

Panasonic doesn’t provide DoD information. All four models have a round-trip efficiency of 90%, placing them in line with the Sonnen Eco. 

Panasonic’s storage systems have a 10-year warranty with different throughput clauses for each model. The standard models include a throughput clause of 30.2 MWh, while the Plus versions have 45.3 MWh. All four models have at least a 60% end-of-warranty capacity.

We reached out to each brand about the cons listed in this article but did not receive a response.

Solar batteries are differentiated by their chemical composition. Lead-acid and lithium-ion batteries are the two most popular types.

Lead-acid batteries have been around for many years. They take longer to charge and have a shorter lifespan than lithium-ion options. They’re also bulkier and heavier. Lead-acid batteries have become more popular for off-grid systems than residential installations. 

Lithium-ion varieties are the most common type of solar battery, with Lithium Nickel Manganese Cobalt Oxide (NMC) and Lithium Iron Phosphate (LFP) being the most popular. NMC batteries have older technology but are more widely used. They provide ample power but are smaller in size. NMC batteries also contain cobalt, which makes them hard to recycle.

LFP batteries are eco-friendly. They have new technology that provides a longer lifespan and better efficiency than NMC varieties.

You’ll need to consider several factors to find the best solar battery for your system.

Battery capacity is measured in kilowatt-hours (kWh) and indicates the amount of energy that can be stored at once. Usable capacity measures the amount of energy that can be used from the battery. This measurement is lower than the actual battery capacity because a portion of the stored energy is used to run the battery. 

Battery capacity should match your solar power production. Batteries that are too big won’t use their full capacity, while undersized batteries won’t keep up with the amount of energy your system produces. Look for batteries with a capacity of 10 kWh, enough for most homeowners’ energy needs. 

Solar systems generate direct current (DC) electricity that must be converted to alternating current (AC) electricity for your home’s appliances. In an AC-coupled system, the energy is converted to AC electricity at the inverter, converted back to DC to be stored in the battery, and then converted to AC for use in your home. In a DC-coupled system, energy is converted only once.

AC-coupled batteries work best as add-ons to existing solar power systems. However, they’re less efficient than their DC counterparts because some energy is lost in each conversion.

DC-coupled batteries are better for new solar installations. They’re more efficient and can be charged by your solar panels when the grid system is down. However, they’re complicated to install and could increase installation costs.

AC coupling has been used more commonly in residential systems, but DC coupling is becoming more popular as more options become available.

Depth of discharge (DoD) refers to the percentage of the battery discharged relative to its overall capacity. This affects lifespan: Regularly discharging a battery at a lower percentage will yield more useful cycles than frequently draining the battery to its maximum DoD. 

Many battery manufacturers limit DoD to ensure the battery will perform long-term. The industry standard is 80% to 100% for lithium-ion batteries and 50% for lead-acid options.

Power ratings indicate the amount of electricity that can be produced in a specific time frame. These ratings are measured in kW or amps and broken into two categories:

Battery capacity and power ratings shed insight on solar batteries’ power potential. High-capacity batteries with low power ratings can run smaller appliances for longer. Low-capacity batteries with high power ratings offer more powerful bursts of energy but drain quicker.

We focus on continuous power in our reviews because it better indicates how efficiently the batteries will power your home.

Round-trip efficiency indicates the energy that can be used after the battery is charged. According to the U.S. Energy Information Administration (EIA), the industry average is around 80%. The higher the percentage, the more efficiently the battery can generate usable energy. 

A 10-year warranty is the industry standard for solar batteries. However, many companies include a cycle clause or throughput clause that can end the warranty early. Look for batteries that have a higher threshold for both clauses.

Solar batteries help homeowners make the most of their solar power systems. They store the excess energy your system generates so that none of your power goes to waste.

The Tesla Powerwall 2 is our top pick for a solar battery due to its high DoD and unrestrictive warranty. The Sonnen Eco is another excellent option, thanks to its variety of modular batteries. The SunPower SunVault is ideal for those looking for a high-capacity battery.

Residential solar batteries can last 5 to 15 years, with lithium-ion batteries lasting the longest. Solar panel systems typically last 20 to 30 years, so you’ll need to replace your solar battery from time to time.

Lithium-ion solar batteries last the longest. They have the best storage capacity and record the highest depth of discharge levels. They cost more than other types, such as lead-acid batteries, but you’ll need to replace them less frequently.

The average home uses 750 to 1,000 watts of energy per hour, so a 10 kW solar battery can last about 10 to 12 hours without recharging. This is enough energy to run your refrigerator and several small appliances during a power outage. However, a high-power system such as an air conditioner will drain the battery quicker. 

Lead-acid and lithium-ion are the two most popular types of solar batteries. Lithium-ion batteries are the best option due to their longer lifespan and larger solar energy storage capacity. However, lead-acid and saltwater batteries are more affordable.

We spent hundreds of hours researching solar batteries, analyzing cycle efficiency, performance, product longevity, warranty and usable capacity data. We compared each metric to industry standards.

We analyzed customer reviews to gauge each battery’s performance and contacted customer service to understand the buying and installation process. We also assessed each manufacturer’s reputation, dependability and contributions to the solar industry.

Once we gathered all relevant data, we used the following scoring system to grade each solar company on a 100-point scale. We then divided the points earned for each provider’s final score on a 5-point scale.

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