There are certain specifications you should use when evaluating your solar battery options, such as how long the solar battery will last or how much power it can provide. Below, learn about all of the criteria that you should use to compare your home energy storage options, as well as the different types of solar batteries.
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Whether you choose a battery manufactured by a cutting-edge startup or a manufacturer with a long history depends on your priorities. Evaluating the warranties associated with each product can give you additional guidance as you make your decision.
Many different types of organizations are developing and manufacturing solar battery products, from automotive companies to tech startups. While a major automotive company entering the energy storage market likely has a longer history of product manufacturing, they may not offer the most revolutionary technology. By contrast, a tech startup might have a brand-new high-performing technology, but less of a track record to prove the battery’s long-term functionality.
Your solar battery will have a warranty that guarantees a certain number of cycles and/or years of useful life. Because battery performance naturally degrades over time, most manufacturers will also guarantee that the battery keeps a certain amount of its capacity over the course of the warranty. Therefore, the simple answer to the question “how long will my solar battery last?” is that it depends on the brand of battery you buy and and how much capacity it will lose over time.
For most uses of home energy storage, your battery will “cycle” (charge and drain) daily. The battery’s ability to hold a charge will gradually decrease the more you use it. In this way, solar batteries are like the battery in your cell phone – you charge your phone each night to use it during the day, and as your phone gets older you’ll start to notice that the battery isn’t holding as much of a charge as it did when it was new. For example, a battery might be warrantied for 5,000 cycles or 10 years at 70 percent of its original capacity. This means that at the end of the warranty, the battery will have lost no more than 30 percent of its original ability to store energy.
A battery’s round-trip efficiency represents the amount of energy that can be used as a percentage of the amount of energy that it took to store it. For example, if you feed five kWh of electricity into your battery and can only get four kWh of useful electricity back, the battery has 80 percent round-trip efficiency (4 kWh / 5 kWh = 80%). Generally speaking, a higher round-trip efficiency means you will get more economic value out of your battery.
The depth of discharge (DoD) of a battery refers to the amount of a battery’s capacity that has been used. Most manufacturers will specify a maximum DoD for optimal performance. For example, if a 10 kWh battery has a DoD of 90 percent, you shouldn’t use more than 9 kWh of the battery before recharging it. Generally speaking, a higher DoD means you will be able to utilize more of your battery’s capacity.
Most solar batteries need to retain some charge at all times due to their chemical composition. If you use 100 percent of a battery’s charge, its useful life will be significantly shortened.
A battery with a high capacity and a low power rating would deliver a low amount of electricity (enough to run a few crucial appliances) for a long time. A battery with low capacity and a high power rating could run your entire home, but only for a few hours.
While capacity tells you how big your battery is, it doesn’t tell you how much electricity a battery can provide at a given moment. To get the full picture, you also need to consider the battery’s power rating. In the context of solar batteries, a power rating is the amount of electricity that a battery can deliver at one time. It is measured in kilowatts (kW).
Capacity is the total amount of electricity that a solar battery can store, measured in kilowatt-hours (kWh). Most home solar batteries are designed to be “stackable,” which means that you can include multiple batteries with your solar-plus-storage system to get extra capacity.
As you consider your solar-plus-storage options, you’ll come across a lot of complicated product specifications. The most important ones to use during your evaluation are the battery’s capacity & power ratings, depth of discharge (DoD), round-trip efficiency, warranty, and manufacturer.
As electric vehicles become more popular, more companies are dedicating significant research and development funds to developing batteries, and they’re expanding into the energy storage business. Tesla is the first mainstream example (with their Powerwall battery), but Mercedes-Benz and BMW are also bringing standalone batteries to the market in 2017.
How long do solar batteries last?
There are two ways to answer this question and the first is to determine how long a solar battery can power your home. In many cases, a fully charged battery can run your home overnight when your solar panels are not producing energy. To make a more exact calculation, you’ll need to know a few variables, including how much energy your household consumes in a given day, what the capacity and power rating is for your solar battery and whether or not you are connected to the electric grid.
For the sake of a simple example, we’ll determine the size of a battery needed to provide an adequate solar plus storage solution with national average data from the U.S. Energy Information Administration. The average U.S. household will use roughly 30 kilowatt-hours (kWh) of energy per day and a typical solar battery can deliver some 10 kWh of capacity. Thus a very simple answer would be, if you purchased three solar batteries, you could run your home for an entire day with nothing but battery support.
In reality, the answer is more complicated than that. You will also be generating power with your solar panel system during the day which will offer strong power for some 6-7 hours of the day during peak sunlight hours. On the other end, most batteries cannot run at maximum capacity and generally peak at a 90% DoD (as explained above). As a result, your 10 kWh battery likely has a useful capacity of 9 kWh.
Ultimately, if you are pairing your battery with a solar PV array, one or two batteries can provide sufficient power during nighttime when your panels are not producing. However, without a renewable energy solution, you may need 3 batteries or more to power your entire home for 24 hours. Additionally, if you are installing home energy storage in order to disconnect from the electric grid, you should install a few days’ worth of backup power to account for days where you might have cloudy weather.
Solar battery lifespan
The general range for a solar battery’s useful lifespan is between 5 and 15 years. If you install a solar battery today, you will likely need to replace it at least once to match the 25 to 30 year lifespan of your PV system. However, just as the lifespan of solar panels has increased significantly in the past decade, it is expected that solar batteries will follow suit as the market for energy storage solutions grows.
Proper maintenance can also have a significant effect on your solar battery’s lifespan. Solar batteries are significantly impacted by temperature, so protecting your battery from freezing or sweltering temperatures can increase its useful life. When a PV battery drops below 30° F, it will require more voltage to reach maximum charge; when that same battery rises above the 90° F threshold, it will become overheated and require a reduction in charge. To solve this problem, many leading battery manufacturers, like Tesla, provide temperature moderation as a feature. However, if the battery that you buy does not, you will need to consider other solutions like earth-sheltered enclosures. Quality maintenance efforts can definitely impact how long your solar battery will last.
From backup power to bill savings, home energy storage can deliver various benefits for homeowners with and without solar systems. And while new battery brands and models are hitting the market at a furious pace, the best solar batteries are the ones that empower you to achieve your specific energy goals.
In this article, we’ll identify the best solar batteries in 2024 based on some of the most desired features and some of the things to consider when choosing a solar battery for your home.
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Best Solar Batteries of 2024
Naming a single “best solar battery” would be like trying to name “The Best Car” – it largely depends on what you’re looking for. Some homeowners are looking for backup power, some are motivated to decrease their reliance on dirty electricity from the grid, and a growing number – especially in California – need battery storage to maximize the savings potential of their solar system.
The best solar battery also depends largely on whether you are installing it with a new solar system or adding it to an existing system.
So, after reviewing the technical specifications of dozens of battery models on the market, we’ve identified a few of the best options for each purpose.
Best solar batteries for backup power
Backup power for grid outages is traditionally one of the most desired features of a solar battery. While most batteries have this feature, a few stand above the rest in 2024.
Franklin Home Power
Quick facts:
- AC-coupled
- Lithium Iron Phosphate (LFP)
- Solar self-consumption, time-of-use, and backup capable
What we like:
If you’re looking to back up everything during a grid outage (including central air conditioning), the Franklin Home Power system is clearly the preferred choice among Solar.com’s network of battery installers.
By combining three 13.6 kWh aPower batteries with a single aGate controller, the Home Power system can provide up to 15 kW of continuous power and 40.8 kWh of usable energy, and a single aPower has a peak power output of 9 kW to handle large surges like an AC or freezer kicking on.
Franklin Home Power specs
Feature
Measurement
Usable capacity
13.6 kWh
Peak power
9 kW (10 seconds)
Continuous power
5 kW
Warranty
70% after 12 years or 43 MWh
Round-trip efficiency
89%
Depth of discharge
100%
Drawbacks:
At 408 pounds, a 13.6 kWH aPower battery is significantly heavier than comparable models. For example, at 359 pounds, LG’s 14.4 kWh HBC battery is over 50 pounds lighter.
It’s also notable that 13.6 kWh is the only battery size offered in the Franklin Home Power system, so it’s tough to build the system to a precise size.
LG ESS Home 8
Quick facts:
- AC-coupled
- Lithium Ion
- Solar self-consumption, time-of-use, and backup capable
What we like:
In addition to the comfort of a globally recognized brand name, the LG ESS Home 8 offers 14.4 kWh of usable capacity, 7.5 kW of continuous power, and 9 kW of peak power, which makes it suitable for large backup loads during grid outages.
LG ESS Home 8 specs
Feature
Measurement
Usable capacity
14.4 kWh
Peak power
9 kW (10 seconds)
Continuous power
7.5 kW
Warranty
70% after 10 years or 59.8 MWh
Round-trip efficiency
90%
Depth of discharge
90%
Drawbacks:
While prices vary by installer and project type, the Home 8 tends to be on the expensive side.
Best DC-coupled batteries
The major advantage of DC-coupled batteries is much higher round-trip efficiency, which can add up to longer backup power and greater bill reductions. Higher efficiency becomes especially beneficial if you’re charging an EV from your solar battery.
It’s worth noting that DC-coupled batteries can be difficult to add to an existing solar system. So, if you plan on going the DC solar battery route, it’s best to install the battery at the same time as the solar system.
Panasonic EverVolt
Quick facts:
- AC or DC-coupled
- Lithium Iron Phosphate (LFP)
- Solar self-consumption, time-of-use, and backup capable
What we like: The Panasonic EverVolt has a hybrid inverter that allows it to be AC- or DC-coupled, which makes it a viable option for both existing and future solar systems. It comes in three sizes – 10, 15, and 18 kWh (nameplate power) – which can be combined to accommodate various system sizes and offers a whopping 7.6 kW of continuous power when paired with solar panels.
Panasonic EverVolt specs
Feature
Measurement
Usable capacity
9 / 13.5 / 18 kWh
Peak power
5.5 / 8.3 / 11.1 kW
Continuous power (with solar)
7.6 / 7.6 / 7.6 kW
Warranty
70% after 12 years
Round-trip efficiency
89% (AC); 94% (DC)
Depth of discharge
90%
Drawbacks:
To be honest, we’re having trouble finding a drawback to this battery option!
LG RESU Prime
Quick facts:
- DC-coupled
- Lithium-ion
- Solar self-consumption, time-of-use, and backup capable
What we like:
With 97.5% roundtrip efficiency, the LG RESU Prime appears to be the most efficient solar battery on the market. If you’re load shifting on a daily basis (because of time of use rates or unfavorable export rates) that extra 7-10% efficiency quickly adds up to greater bill savings than a typical AC-coupled battery.
It comes in two sizes – 10H and 16H – which can be combined in parallel for up to 32 kWh of usable capacity and offer 100% depth of discharge.
LG RESU Prime specs
Feature
Measurement
Usable capacity
9.6 / 16 kWh
Peak power
7 / 11 kW
Continuous power (with solar)
5 / 7 kW
Warranty
70% after 10 years or 32MWh throughput
Round-trip efficiency
97.5%
Depth of discharge
100%
Drawbacks: The two apparent drawbacks of the LG RESU Prime battery are a relatively short warranty life (10 years or 32 MWh) and the fact that as a DC-coupled battery, it is quite difficult to add to an existing solar system.
Most modular batteries
Generac PWRcell DCB
Quick facts:
- DC-coupled
- Lithium Nickel Manganese Cobalt (NMC)
- Solar self-consumption, time-of-use, and backup capable
What we like:
At just 3 kWh per module, the Generac PWRcell is the most flexible and customizable solar battery on our list and perhaps the market. Stack three batteries together for 9 kWh of usable capacity – ideal for Solar self-consumption and light backup – and then add up to three more per cabinet as your storage needs increase.
Plus, you gotta love the 96.5% roundtrip efficiency!
Generac PWRcell DCB specs (3 modules)
Feature
Measurement
Usable capacity
9 kWh
Peak power
N/A
Continuous power (with solar)
4.5 kW
Warranty
10 years or 7.65MWh throughput per module
Round-trip efficiency
96.5%
Depth of discharge
84%
Drawbacks:
As a DC-coupled battery, the PWRcell is challenging to add to existing solar systems. There is also something left to be desired regarding the warranty length and depth of discharge.
Goto OMMO to know more.
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Enphase IQ 5P
Quick facts:
- AC-coupled
- Lithium Iron Phosphate (LFP)
- Solar self-consumption, time-of-use, and backup capable
What we like:
The IQ 5P is by far Enphase’s best and most powerful battery offering to date. Better yet, it’s 5 kWh size and stackability make it incredibly versatile. Use a single module for small-scale self-consumption or stack several together to create a large backup system. Oh, and you gotta love the industry-leading 15-year warranty!
Enphase IQ specs
Feature
Measurement
Usable capacity
5 kWh
Peak power (3 seconds)
7.68 kW
Continuous power (with solar)
3.84 kW
Warranty
15 years or 6,000 discharge cycles
Round-trip efficiency
90%
Depth of discharge
98%
Drawbacks:
The drawback to the 5P is that it isn’t compatible with many of Enphase’s second-generation products, including the IQ 3T and 10T batteries. So, if you already have older Enphase batteries, you may stick with your current generation or consider a full lineup change.
Best solar battery warranties
Tesla Powerwall 2
Quick facts:
- AC-coupled
- Lithium-ion
- Solar self-consumption, time-of-use, and backup capable
What we like:
The Tesla Powerwall 2 is a great overall battery with industry-leading efficiency, depth of discharge, and one of the first “unlimited cycle” warranties. Better yet, it’s often one of the most affordable options and pairs seamlessly with other Tesla products (like EV charging).
Tesla Powerwall 2 specs
Feature
Measurement
Usable capacity
13.5 kWh
Peak power (10 seconds)
7 kW
Continuous power
5 kW
Warranty
70% after 10 years (unlimited cycles)
Round-trip efficiency
90%
Depth of discharge
100%
Drawbacks:
Tesla tends to be a polarizing brand, which may play a role in your decision. There are also more concrete issues regarding customer service and availability (although the latter appears to be improving)
SunPower SunVault
Quick facts:
- AC-coupled
- Lithium Iron Phosphate (LFP)
- Solar self-consumption, time-of-use, and backup capable
What we like:
SunPower is a well-known and trusted solar brand and its 10-year/unlimited cycles warranty is on-par with Tesla’s. If you’re not a Tesla fan and a robust battery warranty is high on your list, the SunVault Strage system offers a great alternative.
SunPower SunVault Storage specs
Feature
Measurement
Usable capacity
13 / 16 kWh
Peak power (10 seconds)
10 / 12 kW
Continuous power
6.8 kW
Warranty
70% after 10 years (unlimited cycles)
Round-trip efficiency
86%
Depth of discharge
92%
Drawbacks:
The SunVault’s round-trip efficiency and depth of discharge are a bit lower than the industry averages and SunPower tends to come with a higher price tag than other brands.
Solar Battery Features
Frankly, there is a lot to consider when choosing a solar battery. The industry jargon doesn’t help and neither does the fact that most battery features are things we don’t think about on a daily basis.
In other words: What does it all mean???
in this section, we’ll give a brief summary of some common battery terms and what they mean.
AC vs DC-coupled
It’s important to understand the difference between Alternating Current (AC) and Direct Current (DC) batteries because DC batteries, while more efficient, can be challenging to add to an existing solar system.
This is due to differences in which type of power is generated, stored, and used in each system, shown in the table below.
System
Type of current
Solar panels
Produce DC power
Batteries
Store DC power
Home (lights, AC, fridge)
Use AC power
Utility grid
Distributes AC power
Existing solar systems typically have solar inverters which change the DC power produced by panels to AC power that can be consumed in your home or exported onto the grid. But if you want to store that AC power in a battery, it needs to be inverted again to DC power.
Each time the power is inverted, a little bit is lost during the inversion process (hence the lower efficiency of AC-coupled systems).
In a DC-coupled system, the DC power produced by the panels can be directly stored in the battery and inverted only once to be used in your home or exported to the grid.
Round-Trip Efficiency
Related to AC vs DC coupling, round-trip efficiency is a measure of how much of the original power put into the power can be retrieved later on.
As we mentioned above, a small amount of power is lost each time it is inverted from AC to DC, or likewise. So, for AC-coupled systems with multiple inversions, efficiency is typically around 85-90% while for DC-coupled systems with fewer inversions can boat up to 97.5%.
If you plan to use your battery on a daily basis to charge an EV or avoid peak time-of-use rates, small differences in efficiency can really add up.
Types of Solar Batteries
The next thing to consider is the composition of the battery. Every battery on our list is either lithium-ion or lithium iron phosphate (LFP). While similar, the differences are noteworthy.
LFP batteries typically have longer lifespans and increased thermal stability (aka less heat and fire risk). They also do not use nickel or cobalt, which can be toxic and dangerous to mine.
Batteries can also be categorized as backup versus consumption-only.
Traditionally, the main feature of solar batteries was to provide backup power for grid outages. However, as net metering policies are weakened and removed, there is a growing demand for batteries that allow homeowners to save money by storing and using their own solar production without providing backup power – known as consumption-only or non-backup batteries.
Why would anyone want this? Well, the components, programming, and labor that go into providing backup capabilities are expensive, and removing these things can reduce the cost of a battery by 20-30%.
So, consumption-only batteries enable all of the bill-savings of a traditional backup battery at around 75% of the upfront cost – which can be well worth it for homeowners who aren’t concerned with grid outages.
Peak and continuous power
Most batteries feature two numbers that represent their capacity to provide power.
Peak power is the measure of the battery’s ability to handle surges of power, like when an air conditioner turns on. This is a short burst of energy that can typically only be sustained for 10 seconds or so.
Continuous power is a measure of how much output the battery can sustain over long periods of time. This figure is especially important if you plan on using a battery for backup power during grid outages.
Usable Capacity
Usable capacity is a figure that represents how much power you can draw from your battery at one time. This is different from the nameplate capacity, which represents the total amount of power a battery can store.
The key difference is draining a battery all the way down to 0% can damage the system and reduce its lifespan. It’s typically recommended to leave at least 10% of the nameplate capacity in the battery at all times to prevent damage, hence the term “usable capacity.”
Depth of Discharge (DoD)
Depth of Discharge is the manufacturer’s recommendation for how much power you can pull from the battery at one time relative to its total capacity.
On our list, this figure ranges from 84% to 100%. So, some manufacturers say “go ahead and empty the tank” while others say it is best to keep a minimum charge of 16%.
Battery Warranties
Like solar panels – and everything else – batteries naturally degrade over time. Battery warranties guarantee a certain level of performance over a stated time frame.
For example, every battery on our list has a warranty guaranteeing that it will have 70% of its original usable capacity available after 10-12 years or a certain level of usage (measured in throughput capacity or cycles), whichever comes first.
How to Choose the Right Solar Battery for You
As we’ve shown above, not all solar batteries are created equal, and the best battery is the one that serves your needs. So, it’s important to begin your search with some goals, beginning with your energy needs.
Assessing Your Energy Needs
In 2024, there are several reasons to want battery storage for your solar system. These include:
- Backing up essential systems for outages (lights, refrigeration, Wi-Fi, medical devices)
- Backing up your entire home (air conditioning, EV charging, heat)
- Load shifting to reduce your energy bill
- Reducing your carbon footprint as much as possible
- Adopting new and pioneering technologies
Your energy goal(s) will play a big part in dictating the best solar battery for you. For example, if your primary goal is bill savings, then you will likely be shopping for smaller batteries than if your goal is to backup your entire home.
Comparing Battery Specifications
Once you’ve used your energy goals to narrow down a few brands and models, take a deeper dive into the specifications. If you’re comparing backup batteries, pay attention to usable capacity and continuous power. If you’re comparing self-consumption batteries that will charge and discharge every day, focus on efficiency.
Evaluating Battery Warranties
Finally, if you’re having trouble deciding between two battery models that check all your boxes, use the warranty offerings as a decision-maker.
While the goal is to never have to use your warranty, it can be worth the peace of mind to have a more robust guarantee on your side.
Conclusion
Let’s face it: Choosing a solar battery can be daunting. However, by starting with your energy goals and focusing on two or three batteries that check your boxes, it can be much easier to identify a storage system that meets your needs.
Solar.com’s eight best solar batteries of 2024 are a great place to start. If you’re ready to compare prices, connect with an Energy Advisor to see exactly how much solar batteries cost through installers in your area.
Solar Battery FAQs
Which batteries are best for solar panels?
Solar.com’s top choices for best solar batteries in 2024 include Franklin Home Power, LG Home8, Enphase IQ 5P, Tesla Powerwall, and Panasonic EverVolt. However, it’s worth noting that the best battery for you depends on your energy goals, price range, and whether you already have solar panels or not.
Which is the best solar battery company?
Some of the best solar battery companies in 2024 include LG, Panasonic, Enphase, Tesla, SunPower, and Sonnen. These companies all have a track record of producing quality products and offer some of the most robust warranties on the market.
Which solar batteries last the longest?
Since solar batteries are a relatively new technology, we are still waiting to see which batteries last the longest. However, it’s worth noting that Tesla and SunPower offer 10 year/unlimited cycle warranties, while Franklin and Panasonic offer 12-year warranties.
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