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Solar batteries store excess energy generated by your solar power system for later use. Pairing solar batteries with a high-performing system can boost your energy savings and extend your solar system’s benefits. Our team spent more than 70 hours researching solar batteries from leading manufacturers and top solar panel companies. Our guide compares the six best solar batteries for residential homes and offers guidance on shopping for storage options.
Since solar batteries can be a complex subject, we’ve included a “Solar Battery Shopping” section below our brand recommendations with common terms and considerations. You can jump to it using this page’s table of contents at any time.
Below is a comparison of our top solar battery picks. We’ll go into more detail in the sections below.
BatteryOur RatingBattery TypeUsable CapacityContinuous Power RatingDepth of Discharge (DoD)WarrantySonnen Eco
4.8 out of 5 stars
LFP
5 kWh to 20 kWh (varies by model)
3 kW to 8 kW
90%
10 years, or 10,000 cycles
Tesla Powerwall 2
4.65 out of 5 stars
NMC
13.5 kWh
5 kW
100%
10 years, unlimited cycles, no throughput clause
LG Chem RESU
4.65 out of 5 stars
NMC
9.8 kWh
5 kW
95%
10 years, 4,000 cycles, or 22.4 MWh throughput clause
Enphase IQ
4.65 out of 5 stars
LFP
3.36 kWh or 10.08 kWh
1.28 kW, 3.84 kW
96%
10 years with a 5-year optional extension, 4,000 cycles (coverage varies by model)
SunPower SunVault
4.6 out of 5 stars
LFP
12 kWh or 24 kWh
6.8 kW to 8 kW
N/A
10 years, 4,000 cycles, or varied throughput clause
Generac PWRcell
4.5 out of 5 stars
NMC
9 kWh to 18 kWh (varies by model)
3.4 kW to 6.7 kW (varies by model)
84%
10 years, varied throughput clause
Fast Facts:
4.6 out of 5 stars
Exclusively through SunPower or its authorized dealers
12
kilowatt-hours
, 24
kilowatt-hours
What we like: Known for its high-efficiency solar panels, SunPower offers an exclusive storage solution called the SunPower SunVault. The company provides two battery options for residential installations. The SunVault Storage 13 offers a 12-kilowatt-hour (kWh) capacity and a continuous power rating of 6.8 kilowatts (kW). Continuous power represents how much backup power a battery provides to your home.
The SunVault Storage 26 boasts a much higher 24-kWh capacity but maintains the same continuous power rating. The 26 model is the largest lithium iron phosphate (LFP) battery in our review. LFP batteries have a longer life span and better safety features than other battery types.
Both SunVault batteries provide a round-trip efficiency of 85%, meaning they lose 15% of their power when charging. According to the U.S. Energy Information Administration (EIA), the average round-trip efficiency is 80%. While the SunVault ranks above this standard, its efficiency is still low compared to other reviewed batteries.
SunPower does not disclose the depth of discharge (DoD) for its battery storage units. DoD represents how much a battery can drain before shortening its life span. Most manufacturers include DoD ratings to protect the battery.
Each battery includes a 10-year warranty, which is standard for most solar energy storage options. These batteries also have additional stipulations that could end the warranty early. The SunVault Storage 13 includes a 38-megawatt-hour (MWh) throughput and a 4,000-cycle clause. Your warranty will end if your battery produces 38 MWh of energy or completes 4,000 full charge and discharge cycles before the 10 years.
The SunVault models have an end-of-warranty capacity of 70%, meaning they will maintain 70% of their outlined storage capacity when the coverage ends. The average end-of-warranty capacity falls around 60%, placing the SunVault batteries at an advantage.
Better-than-average end-of-warranty capacity
Battery is exclusive to SunPower solar systems
Compatible with existing solar systems
Lower round-trip efficiency than other models
Largest usable capacity of our reviewed LFP batteries
Undisclosed DoD information
Read more: SunPower review
Fast Facts:
4.65 out of 5 stars
Exclusively through Tesla or its authorized dealers
13.5 kWh
What we like: The Tesla Powerwall 2 is one of the most popular solar batteries. It provides 5 kW of continuous energy but uses older, less efficient lithium nickel manganese cobalt oxide (NMC) technology. Unlike other modular solar battery storage, the Powerwall comes in one battery size: a 13.5-kWh model. However, you can add multiple Powerwalls to create a larger backup system.
The Powerwall 2 offers a 90% round-trip efficiency and a DoD of 100%. The 100% DoD rating means the Powerwall can drain completely without reducing its performance. A 100% DoD rating is rare and helps set the Powerwall apart from other home battery options.
Benefits and Drawbacks
BenefitsDrawbacksCompatible with existing solar systems
Delayed wait times for Powerwall orders
Leading 10-year warranty with unlimited cycles
Limited availability through Tesla and its dealer network
Up to 10 Powerwalls can be added for backup power
No modular options
Read more: Tesla Solar panel review
Fast Facts:
4.65 out of 5 stars
Available through LG-licensed installers
9.8 kWh
What we like: The LG Chem RESU-10H has a usable capacity of 9.8 kWh, making it well-suited for homeowners with lower energy needs. The LG Chem is stackable, meaning you can combine batteries to reach a total storage capacity of up to 32 kWh. This battery provides 5 kW of continuous power.
The LG Chem RESU-10H includes a 94.5% round-trip efficiency, making it one of the most efficient NMC batteries in our review. The battery also offers a 95% DoD, allowing almost a complete battery drain without damaging the battery capacity or overall life span. Although the LG Chem includes a standard 10-year warranty, it has a rather low throughput clause of 22.4 MWh.
The LG Chem RESU-10H also includes a 60% end-of-warranty capacity. Although this capacity aligns with industry standards, it’s still lower than other battery banks we reviewed.
Better availability than other battery systems
Lower end-of-warranty capacity
More efficient than other reviewed NMC batteries
Not suitable for homeowners with high energy needs
Depth of discharge is 95%
Throughput clause is lower than other battery modules
Fast Facts:
4.65 out of 5 stars
Available from
Enphase
’s sales team, website, or authorized installers
3.36 kWh, 10.08 kWh
What we like: Known for its solar microinverters, Enphase has created the Enphase IQ battery to meet varying energy needs. These batteries work exclusively with Enphase inverters. They also work with gas-powered and solar generators, extending your home’s battery backup options.
This modular battery comes in four models:
This heavier
battery option
provides a
usable capacity
of 3.36 kWh.
This model offers the same capacity as the IQ 3 but in a more compact size.
This bulkier backup battery offers 10.08 kWh of usable storage.
This is almost 24 pounds lighter than the IQ 10 but with the same
usable capacity
.
You can increase your stored energy capacity by combining similar units. For example, you can pair the 3 and 3T models and the 10 and 10T options. These batteries have different continuous power ratings to better match customer needs. The 3 and 3T models provide 1.28 kW, while the 10 and 10T batteries offer 1.85 kW. They all share the same 96% round-trip efficiency and 100% DoD. This places the Enphase efficiency higher than SunVault in both efficiency and DoD.
Enphase backs its batteries with a 10-year warranty and 4,000-cycle clause. However, the throughput warranties vary by model. The 3 and 3T models provide a 9.8 MWh clause. The Enphase IQ 10 models offer 29.4 MWh for the throughput clause. You’ll also receive an end-of-warranty capacity of 70% for each Enphase IQ battery.
Benefits and Drawbacks
BenefitsDrawbacksBetter DoD and round-trip efficiency than SunVault
Additional costs for more warranty coverage
Pairs with solar and gas powered generators
Not suitable for higher-capacity homes
Modular battery options
Must be used with an Enphase inverter
Fast Facts:
4.5 out of 5 stars
Sold through the Generac website and certified Generac installers
9 kWh to 18 kWh (varies by model)
What we like: The Generac PWRcell has four system options with varying configurations, usable capacity, and continuous power ratings. Each system is built with 3-kWh modules, offering homeowners more customization options to create the best battery configuration for their homes.
The Generac PWRcell is the only DC-coupled battery on our list, meaning it stores energy as direct current electricity instead of the alternating current (AC) used to power your home. DC-coupled batteries are more efficient because the energy is only converted from DC to AC once. However, they require a separate inverter. AC-coupled batteries include inverters in their design, making them easier to install. DC-coupled batteries work best in new solar installations rather than existing systems.
Below is a breakdown of each Generac energy storage option:
Generac Model Name Number of Battery ModulesUsable Storage Capacity Continuous Power RatingPWRcell M3
3
9 kWh
3.4 kW
PWRcell M4
4
12 kWh
4.5 kW
PWRcell M5
5
15 kWh
5.6 kW
PWRcell M6
6
18 kWh
6.7 kW
The PWRcell battery has a 96.5% round-trip efficiency and an 84% DoD. This places the PWRcell at the top of our list for round-trip efficiency. However, its lower DoD makes it one of the least efficient battery options.
Each Generac PWRcell includes a 10-year warranty but varies its throughput clauses by model. Here’s an overview of each battery’s throughout clause:
The PWRcell M3 includes a 22.6 MWh throughput clause.
The PWRcell M4 offers a higher 30.2 MWh throughout clause.
The PWRcell M5 increases to a 37.8 MWh throughput clause.
The PWRcell M6 comes with the highest throughput clause of 45.3 MWh.
Better customization with smaller modules
Incompatible with existing solar systems
Highest DoD of any other reviewed battery options
Lowest reviewed DoD
Protective cabinet included for indoor and outdoor installations
Poor performance in extreme temperatures
Fast Facts:
4.8 out of 5 stars
Available through
Sonnen
-certified installers and partners
5 kWh to 20 kWh
What we like: The Sonnen Eco offers more modular battery options than other batteries we reviewed. Each battery comes in 2.5-kWh modules that require at least two batteries for the smallest configuration. You can start with a 5-kWh backup system and increase it to 20 kWh. We explain each possible battery configuration below:
Sonnen Eco Battery ModelContinuous Power RatingUsable CapacityEco 5
3 kW
5 kWh
Eco 7.5
4 kW
7.5 kWh
Eco 10
8 kW
10 kWh
Eco 12.5
8 kW
12.5 kWh
Eco 15
8 kW
15 kWh
Eco 17.5
8 kW
17.5 kWh
Eco 20
8 kW
20 kWh
Sonnen Eco batteries are bigger and heavier than other solar batteries, so they’re not ideal for homeowners with limited space. For example, the smallest configuration weighs 394 pounds, while the Eco 20 weighs 830 pounds.
In terms of performance, the Eco models offer an 81.6% round-trip efficiency and 90% DoD. Each battery has a 10-year warranty and a 70% guaranteed end-of-warranty capacity. These batteries also include a 10,000 cycle clause, the second largest clause behind the Tesla Powerwall.
Benefits and Drawbacks
BenefitsDrawbacks10-year warranty or 10,000 cycle clause
Heavier than other battery options
High 90% DoD
Lower continuous power rating than other battery models
Seven modular battery options for more customized storage
Not suitable for homes with limited space or indoor installations
Different types of batteries offer varying advantages, battery life, and efficiency ratings. We’ve detailed the two most popular types, lead-acid and lithium-ion solar batteries, below.
Lead-acid batteries have the longest history within the solar industry. Known as deep cycle batteries, this type of battery can charge and discharge constantly without any issues.
However, lead-acid batteries have their limitations. They have a lower depth of discharge and can only safely discharge up to 50% of their capacity before impacting their life span. These batteries take longer to charge, have bigger and heavier builds, and last only three to five years. Lead-acid batteries work best for off-grid installations.
Lithium-ion batteries are more common for residential installations. They use a newer technology that gives them a higher energy density, meaning they contain more energy in compact sizes. These batteries charge faster than lead-acid options and have a higher DoD that ranges between 80% and 100%. Lithium-ion batteries have a life span of up to 10 years.
Two popular lithium-ion varieties include nickel manganese cobalt oxide (NMC) and lithium iron phosphate (LFP). NMC batteries are more widely used but use older technology. They offer significant power in smaller sizes. However, they contain cobalt which makes them difficult to recycle. LFP batteries use new technology that increases their life span and improves their efficiency. These batteries are more eco-friendly but cost more than NMC options.
The right solar battery provides adequate backup power to your home during emergencies and extends your system’s productivity. Several factors, such as battery capacity, power ratings, and DoD, can impact a battery’s usefulness and solar system compatibility. We’ve compiled the most important factors to consider below.
Most solar batteries are AC- or DC-coupled. Solar panels work by absorbing sunlight, changing it into direct current (DC) energy, and converting it into alternating current (AC) energy for your home. With an AC-coupled system, your solar inverter converts the AC power into DC power for energy storage, then back to AC power when you need to use it. DC-coupled systems only convert this energy once.
AC-coupled batteries are easier to install and work with existing solar systems. DC-coupled batteries are more complicated to install but more efficient. They’re used for new solar installations.
Battery capacity represents the amount of power a battery can store for later use. It’s typically measured in kilowatt-hours. Usable capacity differs in that it represents how much energy can be drawn from the battery. Solar batteries must use a percentage of their stored energy to run, reducing their usable capacity.
Battery capacity should align with your solar panel system’s production levels. Installing a solar battery that’s too small will cause you to lose excess energy. Using one that’s too large will waste valuable storage capacity.
Solar batteries with a high depth of discharge (DoD) maximize your storage capability and improve your energy savings. Using a solar battery with a lower DoD lowers your energy savings potential, leading to wasted energy storage. Lead-acid batteries only offer 50% DoD while lithium-ion storage options range from 80% to 100% DoD.
Battery pricing varies among companies, third-party installers, and authorized dealers. Newer lithium-ion batteries cost more than lead-acid options. Though more cost-effective, lead-acid batteries need to be replaced more often.
Federal and local solar incentives offer additional solar battery savings. Homeowners can receive up to 30% off solar battery costs with the federal tax credit. This includes a solar battery purchased with a solar system or as a stand-alone option. Homeowners who already have a solar energy system can apply for the credit when upgrading their backup power. States, cities, and utility companies offer additional rebates and incentives. We recommend checking the Database of State Incentives for Renewables and Efficiency (DSIRE) for available incentives in your area.
Power ratings, expressed in kilowatts, measure the energy your battery produces. You’ll see two types of power ratings listed for a battery: peak and continuous.
Peak power represents the amount of electricity a battery can produce instantaneously. Batteries with a high capacity but lower power rating can power smaller devices longer. Batteries with low capacities but high power ratings provide stronger bursts of energy for limited time frames.
The continuous power rating represents the amount of time a battery can power a device. Most batteries offer 5 kW of continuous energy. Anything higher indicates a more powerful battery. We focus on continuous power ratings to help homeowners determine the best battery options for running their homes longer and more effectively.
We recommend matching high-performing residential solar panels with efficient solar batteries to make the best use of your excess energy. Look for solar batteries with a round-trip efficiency of 80% or higher. The higher the round-trip efficiency, the less power is lost when your battery charges.
Check each warranty for its time frame and any additional clauses that could end your coverage early. Throughput and cycle clause thresholds could be met before the end of your contract. Consider batteries with only time frame-based coverage or warranties with higher cycle and throughput clauses.
In addition, review the end-of-warranty clauses to determine your estimated battery output after the warranty ends. Constant cycling and discharging will wear down a battery’s production. Most batteries have 60% end-of-warranty capacity guarantees. We recommend buying a solar battery that exceeds this threshold to maximize your solar storage options for longer.
The right energy storage system extends your solar system’s efficiency, provides sufficient backup power, and boosts energy savings. The SunPower SunVault offers the highest usable capacity for a single battery and supports homes with higher energy usage. Tesla Powerwall, one of the most popular solar batteries, includes the best warranty protection with 10 years of battery use. If your home has lower energy needs, the LG Chem RESU is your best option. We recommend comparing at least three solar batteries to find the best fit for your home.
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Lithium-ion batteries have the longest life span, lasting up to 10 years. Lead-acid batteries last three to five years at most.
The Tesla Powerwall 2 solar battery can last up to 10 years with proper maintenance and care.
Lithium-ion batteries are the best batteries for residential solar energy storage. They have a higher energy density, meaning they store more energy in smaller spaces. They offer better efficiency and have longer life spans than lead-acid solutions. However, lithium-ion batteries are also the most expensive.
Yes, you can run your whole house on solar power and batteries with proper planning. By pairing high-efficiency solar panels with large-capacity solar batteries, you can generate enough energy to run your home with panels by day and batteries overnight. Many people choose to go “off-grid,” meaning they cut ties with traditional utility companies completely and live on self-generated solar energy.
We reviewed dozens of solar batteries and their manufacturers. We then formulated a rating system based on several factors. We evaluated cycle efficiency, usable capacity, warranty length, depth of discharge, and end-of-warranty performance. We assessed each manufacturer’s product catalog for size, variety, and stackability. We also compared each battery’s performance metrics to ensure they matched or exceeded industry standards.
We researched each company’s reputation, solar industry knowledge, and business experience. We also spoke directly to representatives to better understand the buying process. Finally, we learned about each manufacturer’s installation process, whether offered directly through the company or a third-party installer.
Read more: Our Methodology
The Tesla Powerwall 2 is CNET's pick for the best solar battery overall. The Powerwall earned an average score in nearly every category, making it the most well-rounded solar battery we've scored; this makes it more likely to be a solid option for more homes. It's also one of only two batteries we've seen that includes an unlimited-cycle warranty. It's important to remember that batteries aren't a one-size-fits-all product. Even though the Tesla Powerwall 2 doesn't have many glaring weaknesses (aside from Tesla's poor customer service reputation), every battery is different. Another battery might suit your home and individual energy needs much better.
If you've got rooftop solar panels, they might produce more energy than you can use. Your utility might pay you for that energy via net metering, but you can also use it to charge a battery to use later. Once you've got a battery full of clean electricity, you can use it to avoid peak charges under time-of-use rates, decrease your reliance on your utility, use solar energy at night or have a reliable source of energy during a blackout. Solar, plus the right amount of storage, can also make a comfortable off-grid life possible.
I've spent countless hours digging through battery specification sheets and spoken with industry experts to get a better understanding of how these batteries work and what really matters for homeowners who are shopping for a home battery. I created a scoring methodology (more on this below) based on my findings to pick out which batteries stand out among the rest. Since the battery is such a large component, it's important to compare all your options -- even ones not featured in this list. Home batteries are an expensive investment, and due to the site-dependent nature of solar, we encourage you to do your own research and get multiple quotes from several installers before making a decision. A mix of quotes from national and local installers will give you a good price variety.
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7
SCORE
How we score solar panels, products, and services.Hands-on testing of solar equipment and companies is difficult. We examine technical specifications, talk with companies and consider customer reviews to find the best product available.
Read our methodology pageThe Tesla Powerwall is the most average home battery on the market, which works in its favor. But its unlimited cycle warranty is a standout. The Powerwall falls short in modularity and customer service. And it's only available in one size. If you need a capacity upgrade, you'll need to buy another 13.5kWh battery.
Performance
6.7 / 10
Warranty
9 / 10
Capacity & Modularity
4.5 / 10
Pros and Cons
Pros
Cons
The Tesla Powerwall is one of the most well-rounded batteries we've seen. One Powerwall holds 13.5kWh, which is decent. Everything about the Powerwall's performance is decent, too. It has a 90% round-trip efficiency, an impressive 100% depth of discharge (which is higher than average) and an on-grid peak power output of 7kW and 5kW continuous.
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7.35
SCORE
How we score solar panels, products, and services.Hands-on testing of solar equipment and companies is difficult. We examine technical specifications, talk with companies and consider customer reviews to find the best product available.
Read our methodology pageThe Sonnen EcoLinx gives you backup power and access to a virtual power plant network -- lowering your electric bill and potentially earning you extra income. This battery is also incredibly modular and offers one of the best battery warranties we've seen. But it comes with a large price tag and lower efficiency ratings.
Performance
6 / 10
Warranty
10 / 10
Capacity & Modularity
8.5 / 10
Pros and Cons
Pros
Cons
The Sonnen EcoLinx holds between 12 and 20kWh and allows you to upgrade your battery capacity in increments of 2kWh. Or you can buy a 30kWh unit. The warranty covers 15 years and 15,000 cycles. The Sonnen EcoLinx has an incredibly high depth of discharge rating (100%) and a solid on-grid continuous power output of 7.2kW, but a low efficiency rating (81.60%).
It's also one of the most expensive batteries we've reviewed. You'll be eligible to participate in the Sonnen VPP, a virtual power plant program that can help lower your electric bill and bring more renewable energy to the power grid.
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6.3
SCORE
How we score solar panels, products, and services.Hands-on testing of solar equipment and companies is difficult. We examine technical specifications, talk with companies and consider customer reviews to find the best product available.
Read our methodology pageThe LGES 16H Prime has solid performance specs at a reasonable price. If you're looking for a larger battery on a budget, the 16H Prime is worth considering. And you won't need solar panels to use it. But the 16H Prime doesn't offer much else beyond large capacity. The warranty is pretty standard, and capacity upgrades are difficult and expensive.
Performance
7.3 / 10
Warranty
5 / 10
Capacity & Modularity
4.5 / 10
Pros and Cons
Pros
Cons
The 16H Prime is large, holding up to 16kWh. But it isn't very modular. If you find yourself needing more than 16kWh, you'll have to buy another 16kWh battery. You can install up to two 16H batteries for a maximum of 32kWh. The 16H's round-trip efficiency is about 90%, and it has a 100% depth of discharge rating. It has a continuous on-grid power output of 7kW. The 16H battery tends to be cheaper than similar batteries, with prices typically falling between $8,000 and $11,000 before installation. The 16H has a pretty standard warranty -- 10 years and a 70% end of warranty capacity guarantee.
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6.95
SCORE
How we score solar panels, products, and services.Hands-on testing of solar equipment and companies is difficult. We examine technical specifications, talk with companies and consider customer reviews to find the best product available.
Read our methodology pageIf it's modularity you're after, the Generac Pwrcell is a worthy choice. The Pwrcell has a battery cabinet that contains small battery modules that are used to steadily increase capacity. Pricing for the Pwrcell is fair too.
Performance
5 / 10
Warranty
5 / 10
Capacity & Modularity
9.5 / 10
Pros and Cons
Pros
Cons
The Pwrcell battery is sold as a cabinet containing individual battery modules that can incrementally increase your battery capacity. One battery cabinet holds between 9 and 18kWh. Capacity is expandable in increments of 3kWh, making upgrades easy. You can install up to two cabinets for a total of 36kWh.
The Pwrcell offers good round-trip efficiency (96.5%) but falls short on depth of discharge (84%). Customers also raised concerns about Generac's customer service in online reviews. The Pwrcell's warranty is about average, covering 10 years and an end of warranty capacity guarantee of 70%.
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6.85
SCORE
How we score solar panels, products, and services.Hands-on testing of solar equipment and companies is difficult. We examine technical specifications, talk with companies and consider customer reviews to find the best product available.
Read our methodology pageBluetti's whole-home battery, the EP900 Home Battery Backup, is a solid option if you're looking for power and modularity. The system's EP900 inverter has an impressive power output at any capacity. And Bluetti's end-of-warranty capacity guarantee is higher than other options. But it isn't the most efficient.
Performance
5 / 10
Warranty
7 / 10
Capacity & Modularity
8 / 10
Pros and Cons
Pros
Cons
The EP900 system is an inverter stacked on top of Bluetti's B500 battery units. Capacity depends on how many B500 battery units you install -- about 9 kWh with two units, about 18kWh with four, up to 39.6kWh if you install an additional system. Where the EP900 shines is its power output -- a continuous 9kW at any capacity size, or 18 kW with two systems. It's backed by a 10-year warranty with an 80% end-of-warranty capacity guarantee. We found this battery to be slightly cheaper than similar options. It has lower depth of discharge (90%) and round-trip efficiency rating (85%) than peers.
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A solar battery's main function is to store excess electricity generated by your solar panels. If you have a solar battery installed, extra electricity from your solar panels doesn't go to waste. Instead, it goes into storage so you can use that energy during periods of inefficient electricity generation, such as nighttime or cloudy weather.
Solar batteries make it possible to have power during outages. With the right battery setup, you can even go completely off-grid. An off-grid system means energy independence and eliminating your electricity bill altogether. You can still opt for a grid-tied solar system with a solar battery, as well. An on-grid solar system with a battery -- a hybrid solar system -- can help you save some money on your electricity bill by using your stored electricity generated by solar panels.
Just like solar panels, solar batteries come with their own pros and cons. A solar battery can help you lower your electricity costs, provide protection against power outages and lower your reliance on the power grid. Solar batteries are also very expensive, too, sometimes costing as much as solar panels themselves.
Depending on your solar system size, you'll likely need more than one battery. If you plan to go off-grid, be prepared to spend even more money on solar storage.
Advantages:
Disadvantages:
There's much more to consider beyond price. You'll want a battery that matches your household's energy usage and can output enough power to support your home's electricity needs. The more large appliances you have, like HVAC equipment, refrigerators or even electric vehicles, the more power output you'll want.
You should also consider battery modularity (being able to add more energy capacity if you need it) and compatibility with your solar panels. Since solar batteries are expensive, it's a good idea to compare battery warranties as well. A solar battery's lifespan is five to 15 years. Most manufacturers will warranty their batteries for 10 years.
Choosing a solar battery isn't easy, and it's not a decision that should be made on impulse. Take your time evaluating all your options and get quotes from different installers to find the best battery for your household's specific energy needs.
Your solar battery system will be either AC-coupled or DC-coupled. The big difference between the two is the path the electricity takes from your solar panels into your battery. DC means direct current, in which electricity flows only one way, while AC is alternating current, in which the current changes directions in intervals.
If you have an AC-coupled system, the electricity stored in your battery needs to be inverted -- switched between AC and DC -- multiple times before it can be used to power your home. In AC-coupled systems, DC electricity flows from your solar panels to an inverter. The inverter transforms the DC electricity into AC electricity that powers your home. The AC electricity then is transformed back into DC electricity to store in the battery.
If you have a DC-coupled system, the DC electricity generated from your solar panels only needs to be inverted once (to AC electricity) so it can power your home, or it can remain as DC electricity and head straight for battery storage.
Each system type comes with its ups and downs. AC-coupled systems tend to be easier and cheaper to install since they have been around longer, but these systems are less efficient than DC-coupled systems. DC-coupled systems are more complicated to install and usually more expensive, but they tend to be more efficient and have better performance metrics.
Not every solar battery is compatible with every solar panel system. Some batteries are only compatible with a few solar panel manufacturers, while other batteries are more third-party friendly. Before deciding on a solar battery, make sure you know which batteries are compatible with your solar panels.
If you already have solar panels installed, but not a battery, be aware that some batteries are not compatible with existing solar systems and can only be installed with a brand-new system. An installer should be able to tell you which solar batteries are compatible with whatever your current solar situation may be.
A battery's capacity is the amount of energy it can store expressed as a unit of power over time, referred to as kilowatt-hours. The larger the kWh capacity, the more energy your battery can store and use. The more energy you use, the larger your battery capacity will need to be. That said, a smaller battery isn't necessarily a bad battery. Its power output ratings are likely going to be much lower, but if you can live with that, then it's fine.
Long story short: Size doesn't always matter. Install a battery that can keep up with your home's energy consumption, and that is modular enough that you can upgrade if you need to in the future. To find the right size battery for your home, consider getting a home energy audit done or ask your installer if they can perform one for you.
A battery's modularity (or stackability) is how flexible the battery's overall capacity can be. Another way to look at modularity is how easy it is to customize your battery to best meet changes in the energy requirements of your home. Your home's energy needs could grow over time, meaning you're going to need a bigger battery.
When it comes to a battery's modularity, here are a few questions to ask: Can I upgrade the same battery? If not, do I have to buy an entirely new battery? How many batteries can I have hooked up at once? Do they have to be the same size?
For example, let's say you bought a battery with a capacity of 12kWh, which is enough for the time being. But if a year later you decided to install an EV charger or build an addition to your home, your energy needs might exceed your 12kWh battery. If your battery is modular, you'll be able to expand your capacity by hooking up another battery of the same size, installing another battery of a different size to the existing system, or upgrading your existing battery's capacity in smaller increments (usually of 2 or 3kWh). How modular your battery is will depend on the manufacturer. Some batteries are built for easy capacity upgrades, while others are not.
A battery's round-trip efficiency is exactly what it sounds like; how efficient the battery is at storing energy. Round-trip efficiency is what percentage of the energy supplied to the battery actually makes it into storage for later retrieval. The higher a battery's round-trip efficiency, the less energy is lost through the storage process, making your battery more efficient. If your battery's round-trip efficiency is 80%, this means 20% of electricity is lost on its way to storage. On the other hand, if you have a battery with a round-trip efficiency of 100%, no electricity is lost or wasted on its way into storage. Most solar batteries have a round-trip efficiency of around 90%.
Depth of discharge is the amount of energy you can use (discharge) from the battery relative to its maximum capacity. Most manufacturers will disclose a battery's maximum depth of discharge. This number represents the amount of energy (in percentage form) you can safely use from your battery without damaging the battery, according to the manufacturer. The closer the battery gets to 100%, the better.
It's not recommended that you completely drain 100% of your battery's usable capacity. This can shorten its lifespan and make it harder for your battery to hold a charge over time. You'll get more cycle life out of your battery by using as little energy from your battery as you can at a time.
Most solar batteries will have a specified maximum (overall) capacity and a usable capacity.
These capacity numbers can be used to calculate the depth of discharge by dividing the usable capacity by the maximum capacity and then multiplying the answer by 100. For example, if a battery has a maximum capacity of 10kWh and a usable capacity of 9kWh, then its depth of discharge is 90%.
All solar batteries will have peak and continuous power output ratings. Your battery's peak power output is essentially how much power the battery can put out all at once without risking damage. A battery can only "peak" for so long though, so each battery should also disclose how long (in seconds or minutes) it can output its maximum power. Continuous power output is the amount of power the battery can output at all times. If you live in a large home or have a lot of large high-power appliances, you're going to want higher power output ratings. A reputable installer will be able to provide power output recommendations for your home based on your energy usage and power needs.
Note that these power output ratings will also be different depending on if your system is grid-tied or off-grid, and some manufacturers are more transparent about providing these ratings on their product datasheets than others. If you plan on going off-grid, you'll likely need multiple batteries.
Since solar batteries are an expensive investment, it's reasonable to expect a good warranty. Most solar battery warranties will cover up to a certain number of years, cycles, end-of-warranty capacity and throughput. You can expect most solar battery warranty periods to last at least 10 years.
Cycles: Any time you drain your battery, it needs to recharge. This process is called a cycle. Like most batteries, your solar battery will slowly lose its ability to hold a full charge over time. Many manufacturers will typically cover a certain number of cycles in the warranty agreement. The average warranty usually guarantees somewhere between 4,000 and 6,000 cycles.
End-of-warranty capacity: Your battery's overall capacity will decrease over time. A solar battery's end-of-warranty capacity is the manufacturer's guarantee that your battery will be able to store up to a certain percentage of energy capacity by the time your warranty is up. Most manufacturers will guarantee that your battery will still be able to hold at least 60% of its original capacity by the time your warranty ends. This means if you buy a battery with a usable capacity of 15kWh, your battery should be able to store at least 9kWh of energy before your warranty expires.
Throughput: Some battery warranties include a throughput number. A throughput number is the overall amount of energy (typically measured in megawatt-hours) that the battery is expected to deliver during its entire lifetime. This means your warranty is valid until your battery hits its throughput number. In some cases, if you manage to hit your throughput number before your warranty period ends, your warranty will expire.
The typical solar battery warranty covers about 10 years, 4,000 to 6,000 cycles and up to 60% or 70% of your batteries' end-of-warranty capacity. As you shop around for solar batteries, be sure to compare warranties and carefully read the fine print in the agreement.
There are four main types of solar batteries: lithium-ion, lead-acid, flow and nickel-cadmium batteries. Most solar batteries you'll encounter are lithium-ion batteries, while flow and nickel-cadmium batteries are more industrial-focused and not suitable for residential use. On the other hand, lead-acid batteries are lower quality, but cheaper. Here's a breakdown of the different types of solar batteries.
If you're installing a solar battery for your home, it will likely be lithium-ion. These batteries are one of the most common types of residential solar batteries and have a high energy density, allowing them to hold more energy capacity in a smaller space. Lithium-ion batteries usually have a higher depth of discharge too, allowing you to drain more energy from your battery with a lower risk of damage. Plus, they require little to no maintenance, which makes them popular for computers, cell phones and vehicles. The downside is that lithium-ion batteries are expensive, and they tend to overheat and become damaged at higher voltages. If not properly installed, this could result in a fire.
Lead-acid batteries have been around for a long time, making them another popular choice for home battery needs. These batteries have a lower energy density and efficiency rating than other battery types, but they do have a long lifespan (with proper maintenance) and a more mature technology base. Lead-acid batteries are generally cheaper as well.
While flow batteries are indeed a type of solar battery, you won't be seeing them in many homes. Flow batteries are larger batteries (around 2.2 MWh in capacity) and are normally used for grid-scale energy storage. Since these batteries are so large, they are incredibly expensive. They are best suited for industrial use and are not intended for household energy storage.
Because nickel-cadmium batteries are very durable and work well in extreme temperatures, they are a popular battery choice for large-scale commercial and industrial projects. Nickel-cadmium batteries have a high energy density, yielding twice the energy of a lead-acid battery. Unfortunately, cadmium is toxic and is banned in certain parts of the world. Nickel-cadmium batteries are very expensive, too. These batteries are generally not appropriate for residential use.
A solar battery could run your solar estimate up quite a bit. In most cases, the battery will cost almost as much as your solar panels. Solar batteries can cost anywhere from $12,000 to $22,000, according to the US Department of Energy. You can usually find smaller batteries (8kWh or less) for less than $10,000 before installation. The larger your home, the more money you'll spend on solar. As a general rule of thumb, you can usually expect to pay between $1,000 and $2,000 per kWh of energy storage. And solar battery installation fees are typically around $3,000 or more.
Want something smaller than a whole-home solar system? See our picks for the best portable solar panels and solar generators.
Panasonic Evervolt Home Battery: The Panasonic Evervolt Home Battery offers homeowners a modular battery without sacrificing power. It's available in 9, 13.5 and 18kWh capacity sizes, and is expandable in 4.5kWh increments. The Evervolt Home Battery comes with a strong 12-year warranty and a solid continuous power output (7.6kW). In our scoring, the battery falls slightly short in its AC round-trip efficiency and depth of discharge.
SunPower SunVault: The SunPower SunVault is a solid battery, with a great warranty. It's also backed by a solar company with a proven track record and the most efficient solar panels on the market. If you're considering SunPower as an installer, the SunVault is a solid choice for a battery. The biggest standouts with the SunVault are its large capacity options and unlimited cycle warranty. The SunVault is sold as either a single unit (13 or 19.5kWh) or a double unit (26 or 39kWh). The SunVault falls short in efficiency and modularity. It also tends to be more expensive than some peer batteries.
Franklin Home Power: The Franklin Home Power battery received average scores in nearly every category. The standouts for this battery are its 12-year warranty and the fact that you can install up to 15 batteries on one system. It's a good battery if you're looking for a well-rounded battery for adding large capacity expansions. Franklin Home Power is more expensive than similar batteries on the market, and it's a fairly new system, so availability and reliable customer reviews are harder to come by.
Enphase IQ 10T: Enphase batteries are a popular budget pick for home battery systems, but you'll be sacrificing power output and efficiency (on AC-coupled systems) for price.
LG ESS Home 8: While the Home 8 isn't necessarily a bad battery choice, it was beaten out by the LG Resu 16H Prime, which had higher efficiency, performance and capacity scores at a lower price. In comparison, the LG ESS Home 8 system is more modular, allowing you to stack up to four Home 8 systems versus only being able to stack two 16H Primes.
SonnenCore Plus: The SonnenCore Plus falls a bit short in just about every category except for its warranty and price. The warranty is good for 10 years or 10,000 cycles, which is pretty substantial in comparison to other battery warranties, particularly the cycles.
Emporia Alpha-ESS DC Coupled: The Emporia Alpha is a good option if you're looking for a smaller battery with good customer service. This battery is decently modular, too. Unfortunately, the Emporia Alpha falls behind its competition due to lower performance numbers.
Delta BX 12.6: Delta's BX 12.6 battery has decent round-trip efficiency (96%) and depth of discharge (98%), but that's about all it has going for it. Lack of modularity, a subpar warranty and poor power output ratings are what held this battery back.
First and foremost, it's important to point out that 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. 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 efficiency, 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.
After a thorough research process, these were the categories we chose to evaluate each battery on.
We looked at 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 tier-style rating (from 1 to 5) to evaluate which aspects of each battery were above average (among our list), just average or below average.
What is the Tesla Powerwall 3?
The Tesla Powerwall 3 is the next generation of the Tesla Powerwall battery. Like the Powerwall Plus, the Tesla Powerwall 3 comes with an integrated solar inverter. It's also not compatible with Powerwall 2 and Powerwall Plus batteries.
Tesla has shared little information about the battery and there's no spec sheet available yet. But we do know it's twice as powerful as the Powerwall 2, and it comes with a 10-year warranty.
The Tesla Powerwall 3 will be available to customers sometime in 2024. Details on pricing and ordering are still unknown.
Do solar batteries qualify for the federal tax credit?
The federal solar tax credit covers 30% of the total cost of your solar system in tax credits. Solar batteries qualify for the federal solar tax credit as long as your battery can hold at least 3kWh of energy and is installed in 2024 or later.
How long do solar batteries last?
A solar battery's lifespan is typically between five and 15 years. Factors affecting the lifespan of your battery include weather conditions (if outdoors), type of battery, depth of discharge (the less energy you use at one time, the better), installation and usage.
How many solar batteries do I need to go off-grid?
Because solar is so site-dependent, there is no definitive answer for the number of batteries it takes to go off-grid. It's going to be different for everybody. Most homeowners are going to need multiple batteries to go completely off-grid. Your home's energy usage and the size of your solar system are two of the biggest factors determining how many batteries you'll need to go off-grid.
Will a solar battery power my house during an outage?
Yes. Protection from power outages is one of the main reasons why homeowners choose to have a home battery installed. If you have solar panels, installing a solar battery will allow you to store excess electricity generated by your solar panels. This stored electricity can be used at any time, even during a grid outage.
Which type of battery is best for a residential solar panel system?
Deep-cycle lithium-ion batteries are the most popular type of solar battery for residential solar applications. These batteries are durable and require little to no maintenance. They also come with a higher energy density and depth of discharge.
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