On average, solar batteries last between 5 to 25 years. Lithium-ion batteries are the most prevalent solar battery type and have a lifespan of up to 15 years. Some factors that impact a solar battery’s longevity are battery type, installation, depth of discharge, cycle life, environment and maintenance.
Solar is an investment (and for those who aren’t Plico members paying one low weekly fee, it poses a high upfront cost), so you want to get the longest lifespan possible. This article will look at what you can do to maintain your battery’s health and, for those still looking to buy, what information you need to know when choosing your solar battery.
What factors impact solar battery longevity?
As mentioned, a solar battery’s type, cycle life, depth of discharge, storage environment and maintenance all contribute to how long your solar battery will last.
Solar battery type
In 2022, there are many different types of solar batteries on the market. Some of these are lead-acid and flow; however, lithium-ion is now the most common battery type. You can read more about the difference between each of these types of batteries in this article.
Each solar battery type differs in its projected lifespan.
Lead-acid batteries are the oldest solar battery and have one of the lowest lifespans in the market. Lead-acid batteries have a cycle life of between 1500 - 3000 cycles, equating to around three to five years.
Lithium-ion batteries have come to dominate the market. Cycle lives vary, but quality solar lithium-ion batteries far exceed the lifespan of lead-acid batteries. Plico’s solar + battery systems currently use Pylontech’s US3000, a versatile and durable lithium-ion battery. The US3000 has a cycle life of over 6000 cycles and a design life of 15+ years. On the whole, lithium-ion batteries are built for years of output. So while efficiency will reduce slightly towards the end of its lifespan, your solar battery will work reliably and effectively for years.
Flow batteries are a relative newcomer in the solar battery market. They pump liquid electrolytes through electrochemical cells to store and discharge energy. They have a 100% depth of discharge, which exceeds that of lead-acid and lithium-ion batteries. This means they can export their entire capacity without degrading the battery’s health. This translates to a lifespan on the upper end of the range, somewhere between 15 – 25 years.
Despite these positives, flow batteries aren’t taking over the market. They’re still dwarfed compared to lithium-ion battery installations; why? Flow batteries are expensive. They require vanadium, which is costly to source, as well as toxic fluids to run. Currently, the majority of flow battery use is in large-scale industrial operations. This is because there’s more upfront capital to afford a fleet of flow batteries, which can be housed in a safe, contained environment.
Where you choose to install your battery impacts its lifespan. A solar battery stored outside and in the brunt of the elements will deteriorate quicker than a battery in a controlled environment. That doesn’t mean that your battery necessarily has to be stored indoors – although garages are a typical storage area – a sheltered outside area could be fine as well. The working temperature for solar batteries tends to be quite broad.
For example, Pylontech’s US3000 has a working temperature of 0°c - 50°c. This means that it will perform in most weather conditions in the Australian environment. However, when the environmental temperature is outside your solar battery’s working range, its performance will decline and, in severe cases, malfunction or stop working. If this happens regularly, it has the potential to put undue strain on the battery and negatively impact its longevity.
For more information, read our article on the best location to install your solar battery.
Depth of discharge
Each solar battery has a depth of discharge (DoD) – the percentage of the battery’s capacity that can be discharged without damaging the battery’s health. We’ll use the most common home battery type, lithium-ion, as an example.
Lithium-ion batteries have a depth of discharge of between 80% - 95%. The standard DoD of a lithium-ion battery is 90%, meaning that if your battery’s capacity is 13 kWh, you can use 11.3 kWh without degrading the battery. Modern batteries have inbuilt protective systems that will prevent you from being able to use 100% of your battery’s capacity.
Solar batteries come with a variety of cycle lives. A battery’s cycle life is how many times it can perform a full charge and discharge cycle. The cycle life is one of the main determining factors of a solar battery’s lifespan.
Solar batteries aren’t a particularly labour-intensive piece of equipment. Modern technology is advanced and reliable, but it still pays to monitor your battery’s performance to mitigate any issues preemptively. Monitoring your battery’s performance through an associated app (if it has one) is a good way to check that everything is running well.
Plico monitors and maintains all members’ solar + battery systems for 10 years, ensuring any issues are prevented or quickly resolved. Plus, all members can monitor their battery’s performance in real-time through the use of our solar performance app. Check out Plico's Solar Battery Guide for more information.
What sort of warranty should I get with my solar battery?
Lithium-ion solar batteries usually have a 10+ year warranty. Shorter lifespan solar batteries, such as lead-acid, have shorter warranty periods. Chances are that you’re looking for a lithium-ion battery, so what should you look for in a warranty?
Check to see what number of cycles is included in the warranty (the higher, the better) and how it works in relation to time (e.g. it is usually pro-rated in terms of years used. If your battery fails after five years and you want a refund, the refund will be calculated as 50% of the capital cost of the battery).
If you choose a quality battery, you shouldn’t have any major issues, but it’s always good to know what you’re looking for in a warranty before making your purchase.
Interested in learning more? Read our picks for the best solar batteries in Australia in 2022.
What are deep cycle batteries?
Deep cycle batteries are batteries that have a depth of discharge of 80% or higher. As explained above, a DoD of 80% means that 80% of the battery’s capacity can be discharged and charged without deteriorating the battery.
The term deep cycle battery was originally popularised to differentiate between lead-acid batteries back when they dominated the market, but as technology has advanced and improved, the most prevalent batteries are deep cycle.
So in many ways, the term deep cycle battery has become redundant in the solar industry. Nearly all quality solar batteries on the market will have a DoD of 80% or higher. Lithium-ion batteries usually have a DoD of 90%.
How long do solar batteries last in comparison to solar panels?
Solar panels have a longer lifespan than solar batteries. Solar panels will last between 20 - 30 years, whereas a lithium-ion solar battery will last up to 15 years.
There are two key takeaways from this: firstly, it emphasises the importance of choosing a durable, high-quality battery with a high cycle life and a history of reliability; secondly, the installation process matters. Who installs your battery, how it’s installed, and where it’s installed are all critical components in your battery’s longevity. Given that solar panels have a longer lifespan, you need to get every year you can out of your solar battery.
Is the lifespan of a solar battery the most important aspect?
The projected lifespan of your solar battery is one of the most important things to consider when choosing your battery. Look for historical data on a battery’s reliability and efficiency over time; there are reports from test centres such as Battery Test Centre that can be helpful in gathering this information. Each solar battery’s spec sheet should have an outlined cycle life and design life. You can also gauge a solar battery’s durability from the offered warranty. Be wary of any warranty that is less than 10 years.
Get a new solar + battery system installed and maintained for one low weekly fee.
Plico members get an industry-leading solar + battery system with no big upfront costs from one low weekly fee. Our experience specialists will conduct site visits and ensure that your battery is installed correctly and in the optimal location. We also monitor and maintain your system for 10 years to ensure you get optimal performance from your solar battery.
You can view our different solar + battery systems by clicking here or calculate your projected savings with our Solar Savings Calculator. You can also get in touch with one of our switched-on team members by calling 1300 175 426 to see how a solar + battery system can help you save.
Interested in finding out the market price for solar + battery? Read our article How Much Does it Cost for Solar Panels and a Solar Battery? or How Much Are Solar Batteries?.