What is the best solar battery overall?
We’ve evaluated many solar batteries over the course of the year, and the Bluetti EP900 Home Battery Backup is CNET’s pick for the best solar battery overall, overtaking the Tesla Powerwall. The EP900 system earned high marks for its power, warranty, modular design and price transparency. It’s important to note that we scored our batteries based on a backup power use case. Batteries aren’t a one-size-fits-all product. The EP900 system is a solid option for your home, but it might not be your “best” option. Another battery might suit your home and individual energy needs 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. A recent report found the top reason for consumers to consider home batteries was to save money on energy bills — not for backup power. The same report noted that prices are also dropping, making home batteries more affordable.
CNET experts have spent countless hours digging through battery specification sheets and speaking with industry experts to better understand how these batteries work and what really matters for homeowners who are shopping for a home battery. This evaluation methodology assumes you’re using the battery primarily for home backup purposes. If you’re looking to use your battery for time-of-use offset or virtual power plants, then the “best” battery options we have listed might not be right for your situation. Home batteries are a major household purchase and should be treated as such. It’s important to compare all your options, even ones not featured in this list.
Best solar batteries of 2024
Bluetti EP900
Best overall
The EP900 Home Battery’s powerful and modular design gives it a boost over the competition. The system offers three capacity options and an impressive 9 kW of output at any size. The price is available on Bluetti’s website, so there’s no guessing involved. But it’s not the most efficient.
Tesla Powerwall 3
Best well-rounded battery
The Tesla Powerwall 3 is a big improvement from the Powerwall 2. The Powerwall 3 keeps the same 13.5 kWh capacity and warranty as Powerwall 2, but nearly doubles its power output (11.5 kW). The Powerwall still falls short in modularity, price transparency and customer support. It’s only available in one size.
Enphase IQ Battery 5P
Best lower capacity battery
The IQ Battery 5P is a big step up from Enphase’s previous models. It’s a small 5 kWh battery that packs a lot of power. Enphase also offers some of the most robust customer support options that we’ve seen. But the battery falls a bit short in price transparency and modularity.
Generac Pwrcell
Best modular battery
If it’s modularity you’re after, the Generac Pwrcell is a worthy choice. The Pwrcell has a battery cabinet that contains small battery modules. The system’s round-trip efficiency is high as well. Generac also offers plenty of options for customer support. But the Pwrcell’s depth of discharge, warranty and price transparency could be better.
SolarEdge Home Battery
Best warranty
The SolarEdge Home Battery is very well-rounded in its performance. But where it stands out is its unlimited cycle warranty and high round-trip efficiency. It falls a bit behind in modularity, price transparency and customer support options.
How do solar batteries work?
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 goes into storage so you can use that energy later. This stored energy can be used to power your home during periods of inefficient electricity generation, like at night or during cloudy weather.
Batteries also provide other benefits that you don’t even need solar panels for. You can store energy in your battery to use during power outages, or use it to help offset expensive electricity rates.
Pros and cons of solar batteries
Just like solar panels, solar batteries come with their own set of pros and cons. A solar battery can help you lower your electricity costs, provide protection against power outages and lessen your reliance on the power grid. They’re also very expensive, sometimes costing as much as solar panels themselves. Depending on your solar system size and what areas of your home you’re looking to back up, you might need more than one battery.
Pros:
- Backup power during outages
- Offset high electricity costs
- Less reliant on the power grid
- Easier monitoring of your energy consumption
Cons:
- Very expensive
- You might need to buy multiple batteries
How to choose the best solar battery for your home
Your budget is likely the biggest factor at play when choosing a battery, but there’s much more to look for in a battery beyond its price tag. You’ll want a battery that can match your household’s energy usage and has enough output to support the electrical loads in your home that you want to back up during an outage. Keep in mind what exactly you plan to use your battery for. Some batteries are better for backup purposes and others are better for electricity offset and virtual power plant participation.
You should consider modular batteries. These battery designs make it easier to upgrade your energy storage capacity later on, and they tend to be easier to install. Since solar batteries are expensive, you should also compare battery warranties. A lithium-ion-based solar battery’s lifespan is typically anywhere from 10 to 15 years. Most manufacturers offer a 10-year warranty with their batteries, but there are some outliers.
Choosing a battery isn’t easy, and it’s not a decision that should be made on impulse. Take your time evaluating all your options. Local installers are going to be your best source of information on what kind of battery is best for your household’s energy needs and goals. They’ll also be able to provide you with quotes on how much things are going to cost.
The difference between AC and DC coupling
When your installer goes to wire everything up, your battery will be either AC-coupled or DC-coupled. The big difference between the two is the path the electricity travels between your solar panels, battery and home, as well as the number of times that electricity is converted.
DC means direct current, in which electricity flows only one way. AC is an alternating current, in which the current is capable of changing direction. The important thing to note is that your solar panels generate DC electricity, but your house (and the power grid) runs on AC electricity. Then there’s your battery, which can only store DC electricity.
This is where a key piece of equipment known as an inverter comes into play. The inverter acts as a sort of translator between your solar equipment and your house, converting the DC electricity from your panels and battery into AC electricity that your home can use.
In an AC-coupled system, electricity from your battery will need to be converted three times before it reaches your home. Your solar panels generate DC electricity and then are sent to your main solar inverter where the DC electricity is converted into AC electricity. From there, this AC electricity can either go straight to power your home or be sent to the battery for storage. If it goes to the battery, that AC electricity will need to be converted back to DC first. This is where a separate inverter for the battery becomes necessary.
The AC electricity is converted to DC via the battery inverter and is then stored in the battery. When you’re ready to pull energy from the battery to send to your home, it goes through the battery inverter once last time (from DC to AC). Needless to say, this is a pretty inefficient process.
An AC-coupled system.
In a DC-coupled system, things are much simpler. There’s less equipment involved and you’ll only need to convert electricity once. The DC electricity generated from your solar panels will either go into the battery with no conversion necessary, or it goes to the main solar inverter to be converted to AC electricity. Once that conversion happens, the AC electricity is sent to power your home.
A DC-coupled system.
Time-of-use offset
Solar batteries aren’t just good for providing backup power. A battery can help you save money on your electricity bill, especially if your utility charges time-of-use rates. The best part is you don’t even need solar panels for this to work.
Some utilities charge more money for electricity use during hours of the day when the demand for electricity is high, like mornings and evenings. Rates during these specific hours can sometimes be double the normal electricity rate or higher.
A battery can help you avoid these high time-of-use rates by using the stored energy from your battery to power your home during these peak hours. Your solar panels can help recharge the battery. During hours of normal electricity rates, you can charge up your battery using power from the grid as well.
Energy storage capacity
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. Aside from price, a battery’s energy storage capacity should be one of your biggest considerations when battery shopping. Your battery should be sized based on your household’s energy usage and which appliances or areas in your home you want to keep powered up during an outage. Depending on your backup power goals, you might need multiple batteries to achieve what you’re looking for.
The more energy you use, the larger your battery capacity will need to be. Batteries with more storage capacity tend to be more expensive, and powering everything in your home during an outage is a bit unrealistic. Because of this, we recommend choosing a few essentials to send backup power to. Things like your fridge, router, TV, microwave and lights are good choices to keep you comfortable and ensure that the battery won’t run out of juice within the first hour or two. Just pick a few rooms to keep powered up instead of the entire house.
Your installer should be able to size an appropriate battery system for your home based on your energy needs. Make sure that you’re both on the same page about the expectations of the battery and exactly what’s going to have power during an emergency. You don’t want any surprises.
Modularity
Many batteries on today’s market feature a modular design. Modular batteries are essentially a few small battery modules connected together inside one or several enclosures. So instead of one giant 15 kWh battery that weighs 300 pounds, you might have three small 5 kWh battery modules that sit on top of each other in a sort of “battery cabinet” or enclosure. This type of battery design often benefits you and the installer.
Modular batteries offer you a bit more control over your battery’s capacity, allowing you to more easily find a size that’s “just right” for your energy needs. The biggest benefit is the ability to upgrade your energy storage capacity without having to buy another giant battery, as long as there’s room inside the battery enclosure. If you’re at maximum capacity, you’ll have to buy another battery enclosure.
Modular batteries also tend to be easier for installers. The battery modules tend to weigh less than 60 pounds, making them much easier and safer to carry. Some batteries might only require one or two installers. This could save you some money on labor costs. In some batteries, each battery module is monitored separately, so if something goes wrong and you need maintenance, your installer can identify exactly which module is failing more quickly. If a module needs to be replaced, it’s usually as simple as pulling the dead module out and then sliding a new one in. You won’t need to go through the hassle of replacing the entire battery.
Round-trip efficiency
A battery’s round-trip efficiency is exactly what it sounds like; how efficient the battery is at storing energy. Round-trip efficiency is the percentage of energy sent to the battery that actually makes it into storage without getting lost, typically to heat.
The higher a battery’s round-trip efficiency, the less energy you’re losing. If your battery’s round-trip efficiency is 80%, this means 20% of the electricity sent to the battery is lost on its way to storage. You’ll notice most solar batteries have a round-trip efficiency of around 90%.
Depth of discharge
Depth of discharge is the amount of energy you can use (discharge) from the battery relative to its maximum capacity. 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. Most manufacturers will disclose this figure, but some don’t. The closer the battery gets to 100%, the better.
If the depth of discharge is not disclosed, you can get an idea of what it might be on your own as long as you know the battery’s maximum and usable capacities. Most will have a specified maximum (overall) capacity and a usable capacity.
- Maximum capacity: The total amount of energy the battery allows you to store.
- Usable capacity: The amount of energy in the battery that you can use.
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%.
Even if you can drain your battery to zero, It’s not recommended. 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. Some manufacturers have a little energy storage capacity set aside in the battery to be used to revive it if the battery runs out of charge.
Power output
All batteries will have peak and continuous power output ratings, measured in kilowatts. Some manufacturers only disclose the continuous rating. These ratings essentially tell you how much power the battery can handle in certain situations.
Peak power represents how much power the battery can put out all at once without risking damage. A battery can only “peak” for so long; this surge of power usually lasts for less than a minute. Kind of like when your air conditioner or fridge kicks on. Continuous power is the amount of power the battery can support at any given moment.
If you live in a large home or have a lot of large power-hungry appliances that you plan on backing up, you’re going to want higher power output ratings. Larger appliances like your HVAC, refrigerator, pool pump and EV charger are going to require more power to run. The battery in an EV is typically several times larger than the average home battery you use to power your house, so it’ll likely eat up your stored energy a lot faster. A reputable installer will be able to provide recommendations for your home based on your energy usage and power needs.
Your home battery’s power output determines the number of loads you’ll be able to back up.
Warranty
Solar batteries are an expensive investment, so you should be expecting a good warranty. Most battery warranties will cover up to a certain number of years, cycles or throughput and offer an end-of-warranty capacity guarantee.
Years: You can expect most battery warranty periods to last at least 10 years. We’ve seen plenty of manufacturers offering 12-year warranties as well. Anything above 12 years is pretty uncommon, but some batteries on the market offer 15-year warranties. Just keep in mind that once your battery hits a certain cycle count or delivers a certain amount of energy during its lifetime, your warranty will expire, regardless of how many years you have left.
Cycles: Any time you drain your battery, it needs to recharge. This process is called a cycle. Like most batteries, your 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 8,000 cycles.
There are outliers on the market that will cover 10,000 cycles or more. Some batteries, like the Tesla Powerwall and the SolarEdge Home Battery, offer unlimited cycle warranties.
Throughput: Some battery warranties include a throughput clause. The battery’s throughput is the total 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. In most cases, if you manage to hit your throughput before your warranty period ends, your warranty will expire.
End-of-warranty capacity: Your battery’s usable capacity will decrease over time. A 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 by the time your warranty is up. Most manufacturers will guarantee that your battery will still be able to hold at least 70% 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.
How much does a solar battery cost?
A solar battery could run your solar estimate up quite a bit. In some 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. Solar battery installation fees are typically around $3,000 or more.
Because most battery manufacturers don’t ship these products directly to you, they tend to be very nontransparent about price. To a degree, this is understandable. The manufacturer doesn’t know your energy consumption or needs, and they can’t predict how much money every installer is going to charge for installation and labor. Some manufacturers, like Bluetti and EcoFlow will ship their batteries directly to you. When it’s shipped to you, you’ll get to see exactly how much the product costs. It’s up to you to find an installer or hire an electrician to get everything connected to your home.
Manufacturers should know at least the minimum amount that their battery sells for, regardless of upcharges from third parties. Some manufacturers will display a “starting at” price or some form of ballpark estimate on their website, but this is very uncommon. This lack of straightforward pricing information can make shopping around for batteries frustrating and tedious.
Want something smaller than a whole-home solar system? See our picks for the best portable solar panels and solar generators.
Solar batteries are a costly investment.
Other batteries we reviewed
Franklin Home Power: The Franklin Home Power battery is a solid option, receiving an average score 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 for a total energy storage capacity of 204 kWh. It’s a good battery if you’re looking for a well-rounded battery for adding large capacity expansions. Franklin Home Power is also more expensive than similar batteries on the market.
Panasonic Evervolt Home Battery: The Panasonic Evervolt Home Battery didn’t make our top five, but it’s still a great option for those wanting 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.
Emporia PowerStation: Emporia’s PowerStation isn’t a bad option if you’re looking for a modular battery. We found other modular options on the market to be a bit better. The PowerStation is available in 9, 13.5 and 18 kWh capacity sizes and you can install up to four units for a total capacity of 72 kWh. Its best features are its 12-year warranty and 7.6 kW of continuous power. We also found Emporia to be one of the most price-transparent manufacturers. You’ll be able to get a quick quote online without giving away any personal information. There are cheaper options on the market and some of the PowerStation’s performance specifications fall behind the competition.
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 already considering SunPower as your solar installer, the SunVault is a good 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). It falls short in efficiency, power and modularity. We also found fewer options for customer support in comparison to other battery manufacturers.
Savant Power Storage 20: If you’re looking for a battery to integrate with your ever-expanding smart home ecosystem, the Savant Power Storage 20 is likely one of your best options. It’s designed as an intelligent smart energy system, designed to give you more control over your home’s energy use on the circuit level, as well as provide backup power during an outage. Based on the categories we use to score batteries, it didn’t make the cut. The Power Storage 20 has a very impressive 12.5 kW continuous power output, and its efficiency and warranty aren’t too shabby either. It falls short in the depth of discharge, modularity and customer support options. It’s also one of the more expensive batteries on the market.
Sonnen Ecolinx: The Sonnen Ecolinx is a solid option if you want to participate in a virtual power plant. Most of Sonnen’s batteries are designed with VPP functionality in mind first and backup power second. The Ecolinx has an excellent 15-year warranty, covering 15,000 cycles. It also features a modular design. You can install between 12 kWh – 20 kWh, expandable in increments of 2 kWh. In comparison to other batteries, the Ecolinx has poor efficiency (81.6%) and is very expensive. We also didn’t see many options for customer support on Sonnen’s website.
LG ESS Home 8: LG has the benefit of being a household name, and you might already have other LG appliances in your home. The Home 8 isn’t necessarily a bad battery choice, but it lags behind the competition in just about every category we score for. We did find its warranty and price to be a bit competitive.
LGES 10H & 16H Prime: Both the 10H and 16H Prime batteries are pretty barebones in terms of cool features, but if you’re after a fairly standard battery with a standard warranty, then one of these might be for you. These batteries are a bit older, so the performance specs and overall design are starting to show their age a bit. They also tend to be a bit cheaper than other options. The LGES 10H and 16H Prime aren’t modular batteries, and you can only install up to one other unit, making capacity upgrades more difficult. Customer support options are lacking as well.
Sonnen Core Plus: The SonnenCore Plus falls a bit short in just about every category except for its warranty and depth of discharge. The warranty is good for 10 years or 10,000 cycles, which is pretty substantial in comparison to other battery warranties, particularly the cycle life. Like most Sonnen batteries, the Core Plus falls short in efficiency, power and customer support options.
Sonnen Evo: Sonnen’s Evo battery model shares the same pros and cons as the Core Plus. The Evo’s warranty is also 10 years or 10,000 cycles and has a 100% depth of discharge. It falls short in just about every other category, particularly efficiency, power, modularity and options for customer support on Sonnen’s website.
Tigo EI Battery: The Tigo EI Battery landed an average score in most categories and has very few standouts. We found its price and efficiency to be better than other batteries. It lags behind the competition a bit in every other category.
Enphase IQ Battery 3/3T & 10/10T: Both of these batteries scored on the lower end in almost every category. The biggest highlight for the IQ Battery 3/3T and 10/10T is their price, which usually tends to be cheaper than other batteries on this list. Enphase also has a plethora of options for customer support, including live chat and 24-hour availability. Most manufacturers only have a support email and phone number.
Home batteries can help you through a blackout
Whether you have solar panels or not, you might want to consider getting a home battery if you’re worried about power outages. Batteries can run your home for hours or even days when the power goes out, and if you live in an area where that happens frequently, it might be a good investment.
We looked at data from the US Energy Information Administration to put together a map of how many power outages per year, on average, the average utility customer in each state had from 2018-2022 (using all reporting methods). We also put together a map showing the average total duration of outages per year, in hours. Generally, states along the coast and those in the Southeast had the most and longest outages.
A home battery is one way to provide backup power, but it isn’t the only thing. You can use a portable power station for a smaller, more limited backup solution. A fuel-powered generator is also a possibility.
How we evaluated the best solar batteries
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. This list also assumes you’re purchasing a battery for the main purpose of using it for energy backup. If you mainly plan to use your battery for energy offset or virtual power plant purposes, there are likely better options than what we have featured on this list. We strongly encourage you to do your own independent research, as well as speak with installers in your area. An installer will be able to get a better understanding of your home’s energy use and what sort of system you might need.
We used a few ways to evaluate and compare these batteries to find the stand-outs. Here’s how we developed our list of top solar batteries.
First, we determined which categories would be used to evaluate each battery’s performance, capacity and value. We also weighted each category. The weight of each category reflects the importance we felt was relevant to the average consumer.
- Modularity: 20%
- Warranty: 20%
- Round-trip efficiency: 15%
- Power output: 15%
- Depth of discharge: 10%
- Price: 5%
- Price transparency: 5%
- Customer support options: 10%
We looked at more than 15 of the most widely available batteries on the market and collected the data for each category to compare the numbers. Each category (for every battery) was given a 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.
Solar battery FAQs
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 10 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?
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.
Source: CNET
