How Long Do Solar Panel Batteries Last?

There are so many benefits to adding battery storage to your solar power system, from increasing energy independence to saving more on utility bills. But solar battery storage can also be a significant investment, and it's important to weigh up your options carefully. One of the most common questions we get is around battery lifespan. 

In this blog, we’ll explain how long solar batteries last, factors that affect solar battery lifespan, and signs that you may need to replace your solar battery. 

Key takeaways:

• Lifespan is largely dictated by recharge cycles, rather than simply time. 
• The typical warranty for a solar battery is 10 to 12 years, but it can vary by manufacturer and product. Some batteries may have a 12 or 15 year warranty.
• There are three types of solar batteries: lead acid, lithium-ion, and flow batteries. The most popular is lithium-ion.
• Factors that affect a solar battery’s lifespan include the type of battery, frequency of use, the environment it's stored in, and how well it’s maintained.  

How long do solar batteries last?

The most common type of solar battery is lithium-ion, such as the Tesla Powerwall. Under average operating conditions users can  expect an operational lifespan of around 10 to 15 years, depending on various factors (we’ll cover this later in the article). While this is a fair amount of time, it does mean you’ll likely need to replace your solar battery at least once within the 25 to 30 years lifespan of your solar panel system. 

Thankfully, solar batteries don’t just suddenly stop working once they reach the end of their lifespan. Instead, their performance will slowly decline over time until it's no longer recommended or feasible to continue using them. As such, monitoring the batteries performance over time will give you some insight into its health and remaining time. 

Battery lifespan can be measured in two ways: 

• Useful life: This refers to the period during which a battery can store and supply enough energy to meet your needs. Useful life usually ends when a battery can only retain around 60% of its original capacity. While it’ll still be able to function beyond that point, it probably won’t provide enough charge to adequately meet your needs. 
• Warrantied life: This represents how long the manufacturer guarantees the battery will perform under normal conditions. Depending on the brand and model, this is usually around 10 years from the date of installation. Many warranties also account for maximum cycle allocations or total energy throughput, meaning your warranty could expire if your battery reaches one of these milestones before the time period is up. Every warranty is different, however, so it’s important to check this before you purchase a solar battery. 

Similar Reading: How To Choose a Home Battery Backup System?

Factors that affect the lifespan of solar batteries

Various factors can affect the lifespan of your solar batteries, including: 

• Frequency of use
• Type of battery
• Environmental conditions
• Maintenance. 

Let’s explore how each of these variables affects solar battery lifespan. 

Frequency of use

Just like your smartphone or laptop, the frequency of your solar battery usage can affect its lifespan. The more you charge and discharge your battery, the quicker it’ll lose its ability to hold a charge. Eventually, after a number of cycles, your battery might struggle to store and release enough energy to be truly useful. 

This is why solar battery lifespans can vary so greatly – the more you use your solar battery, the shorter its lifespan. So if you rely on your battery only during a power outage, it will last longer than a battery that is discharged and recharged every day. 

To help extend solar battery life, pay attention to the manufacturer’s recommended depth of discharge (DoD). This percentage tells you how much of a battery’s stored energy you can safely use without harming its health. For example, the standard DoD of a lithium-ion solar battery is around 90%. This means that with a capacity of 13 kWh, you can use up to 11.7 kWh while limiting battery degradation.

It’s important to not push your battery beyond its recommended DoD as that can significantly reduce its lifespan. Fortunately, most modern batteries have inbuilt protective systems that stop you from draining 100% of their capacity. 

Type of battery

There are three main types of solar batteries: lead-acid, lithium-ion, and flow batteries. Each of these battery types has a different composition, storage capacity, and expected lifespan. 

Lead acid

Lead acid batteries are the oldest type of solar battery, known for a high watt-hour capacity and low price point that makes them popular in off-grid solar systems. However, their lifespan is the shortest on the market at around five years. 

These batteries also have a low depth of discharge (DoD) rate, usually ranging from 30% to 50%. This means you can only use a small portion of stored energy at a time, which can be quite limiting. While the lower price point of lead acid batteries might be attractive, their shorter lifespan and need for more frequent replacements can add up to make them more costly in the long run. 

Lithium-ion

Lithium-ion batteries are the most common solar batteries on the market, with the best storage capacity and longest  lifespan. They have a DoD rate of 80% to 95%, depending on the manufacturer, which means you can safely access  more stored energy without compromising the battery’s lifespan. 

Lithium-ion batteries are more expensive than lead acid batteries, although the long lifespan of around 10 to 15 years can make the added investment worth it by saving you money on replacements over time. 

One thing to note is that lifespans can vary even within the broader category of lithium-ion solar batteries. According to the National Renewable Energy Laboratory (NREL), for example, lithium iron phosphate (LFP) batteries are less affected by certain degradation factors, such as high temperature and DoD, than lithium nickel manganese cobalt oxide (NMC) batteries. On the other hand, NMC batteries are less affected by a high average state of charge (keeping the battery fully charged for extended periods) than LFP batteries. 

This highlights that there’s rarely a clear-cut answer when it comes to solar battery lifespan, and the type of battery you choose – as well as how you use it – can both significantly impact how long it lasts. 

Keep Reading: How Many Batteries Do You Need To Run a House on Solar?

Flow 

Flow batteries are a relatively new player in the solar energy market. They work by storing energy in liquid electrolyte solutions that flow through a cell stack to charge and discharge. This unique design eliminates the need for corrosive materials found in other battery types, with the most common types using vanadium ions or zinc bromide. 

One standout feature of flow batteries is their 100% DoD, which means you can fully deplete the stored energy without damaging the battery. Depending on their specific type, flow batteries can have lifespans of more than 25 years. While they show promise as an alternative to lithium-ion, flow batteries are an early-stage technology and have yet to take over the market – mostly due to their higher costs compared to the other two options. 

Comparing the lifespan of different battery types

Below is a quick snapshot of the lifespan of different solar battery types. 

Environmental conditions

The environment where your solar batteries are stored can also affect their lifespan, especially when it comes to temperature. Generally, solar batteries are best kept out of extremely hot or extremely cold temperatures. If you store your battery outside, exposed to the harsh elements, it’s likely to degrade faster than if you were to keep it indoors in a more controlled environment. That doesn't mean you have to store your solar battery indoors – even a sheltered outdoor area can make a difference. 

When temperatures are too hot, the chemical reaction in batteries happens more quickly. This naturally increases wear and tear and shortens the battery’s lifespan. In colder temperatures, on the other hand, electrons slow down and chemicals don’t last as long as they usually would, making the battery drain much faster. 

Again, the type of battery you choose plays a role here: 

• Lead acid batteries: Tend to be more sensitive to temperatures. Most manufacturers recommend keeping them in temperatures between 40°F to 80°F. 

• Lithium-ion batteries: Less sensitive to temperatures, able to handle slightly below 0°F and even up to 140°F, although storing them in more mild conditions if possilbe is recommended. 
• Flow batteries: Sit in between lead acid and lithium-ion batteries when it comes to temperature sensitivity, performing their best between 23°F and 104°F. 

Most solar batteries are able to handle environmental conditions outside their working range. But if they’re exposed to higher or lower temperatures too often, it can put extra strain on your battery and affect its performance or lifespan. 

See More: Maximizing Solar Efficiency in Extreme Heat: A 2024 Guide

Maintenance

The beauty of solar batteries is that minimal maintenance is involved. In fact, you don’t need to do anything to keep your solar batteries functioning well, unless you notice an issue with their performance or appearance. In that case, you should contact your solar battery installer and ask them to perform an inspection and any necessary repairs. 

That said, there are a few things you can do to make sure your solar battery lasts as long as possible. This includes: 

• Monitoring its depth of discharge (DoD) to make sure it’s in line with the manufacturer’s recommendations. To recap, DoD is the percentage of stored energy you use compared to the overall capacity of the battery. So if your battery has a 90% DoD, then always keep it charged to at least 10% capacity. 
• Regularly checking charge and discharge levels to make sure the battery is working as it should be. Most lithium-ion batteries have Wi-Fi capabilities and can be monitored via smartphone app. Check this regularly to keep an eye on performance. 
• Keeping your battery in a cool and dry environment, away from direct sunlight.

With proper maintenance, solar batteries can maintain optimal performance and last longer.

Similar Reading: How Long Do Solar Panels Last?

Signs your solar battery is degrading

There are a few signs that can signal your solar battery is nearing the end of its lifespan. These can slightly differ depending on the type of solar battery you have and how you use it, however here are some things to look out for: 

• Its capacity is reduced: One of the main signs of an aging solar battery is reduced capacity, meaning it doesn’t hold as much energy as it used to. If you notice shorter discharge times than usual, your battery’s capacity could be reduced. 

• It needs more frequent charging: When a battery’s capacity is reduced, it’ll need to be recharged more frequently. If you notice yourself charging your battery more often, it could be a sign of degradation. 

• It overheats: Sometimes, older batteries can generate more heat than usual when charging and discharging. If your solar battery seems to be unusually hot, it could be nearing the end of its lifespan. 

• It shuts down unexpectedly: An aging battery can struggle to deliver power, leading to unexpected shutdowns. This tends to happen more often during periods of high demand. 

• It flags more issues: Most new solar batteries are equipped with a Battery Management System (BMS) that monitors the battery’s health. If your BMS is constantly flagging issues, it could be time to get a new battery. 

What’s a deep cycle battery?

Deep cycle batteries have a depth of discharge (DoD) of at least 80%. This means you can use 80% of a battery’s stored energy without affecting its health. Most high-quality solar batteries on the market today are deep cycle batteries. 

What’s the lifespan of solar batteries vs solar panels?

With a lifespan of around 25 to 30 years, solar panels last longer than solar batteries. The most popular lithium-ion solar batteries last around 15 years, meaning you’ll likely need to replace your solar battery once throughout the lifetime of your solar panels. That said, when it comes time to change your energy storage, solar batteries will likely be much more affordable than they are today. 

Get the right solar battery for your needs

Solar batteries can help you maximize the efficiency of your solar system and get more out of your investment. With a solar battery, more of your home’s overall electricity use will be fulfilled by your solar array, reducing your utility bill and reducing your carbon footprint. But with so many options out there, it can be difficult to know which choice to make. We’re here to help!

Our expert solar consultants can help you choose the best solar battery setup for your needs, whether you're looking for backup power during an outage or a whole-home storage solution. We’ll also show you how to optimize usage to maximize your battery’s lifespan. If you’re ready to explore solar battery options or have questions about upgrading your system, contact Sun Valley Solar Solutions today for free, no-obligation guidance.