If you’re thinking about investing in a solar battery, one of the most important questions you’re likely to have is, ‘How long do solar batteries last for?’
With solar panels lasting around 30 years, it’s important to understand the lifespan of an accompanying battery storage as this will directly impact long-term practicality, cost-effectiveness and energy efficiency of your renewable system.
In this article, we’ll take a look at the average lifespan of a solar battery, the factors affecting longevity, as well as how you can maximise your battery lifespan to get the most return on your investment.
How long do solar batteries last?
On average, solar batteries last between 10 and 12 years. Some high-quality models will last 15 years and longer.
Solar storage batteries are designed for daily charging and discharging cycles. But as you know from your laptop and phone, batteries do experience a decline in performance over time. That said, solar batteries typically have a much longer lifespan than these devices.
Another good way to measure solar battery longevity is through the number of charging cycles it gets through. A good quality solar storage battery will achieve around 6,000, but up to 10,000, cycles before their capacity starts to diminish.
The frequency of these cycles depends on the household’s energy use patterns. They can also vary with the seasons. For example, in the summer you’re likely to get through more cycles thanks to your battery being topped up more often by the sun.
The vast majority of solar storage systems are made with a lithium-ion battery. As a battery storage type, they’ve almost wiped out their lead-acid battery predecessor over the last few years.
Lithium-ion batteries bring extra benefits to the table, such as better energy density, greater depth of discharge and a longer lifespan. On average, lead acid batteries only last between 3 and 7 years.
As technology improves, solar battery lifespans will gradually increase even further. You can read more on the benefits of solar battery storage here.
Factors affecting battery longevity
- Depth of Discharge (DoD) – Measures how much of a battery’s total capacity has been used before it’s recharged. For example, if a 10 kWh battery has discharged 8 kWh, the DoD would be 80%.
DoD is an important factor in determining a battery’s lifespan, as regularly discharging a battery to a high DoD (such as 80% or more) can lead to faster degradation of the battery’s capacity over time. Modern lithium-ion batteries are getting better and can withstand higher DoDs without significant impact on their longevity. Some advanced solar batteries now offer 100% DoD. - Type of battery – Longevity is directly affected by type of battery and quality of materials. Lithium-ion batteries currently lead the market and are known for their extended lifetimes compared to alternatives.
- Conditions – Exposure to extreme temperatures and conditions can affect a solar battery’s performance and longevity. Solar batteries operate most efficiently in a cool, dark location.
- Maintenance – Lithium ion solar batteries don’t need much maintenance, but it’s still important to regularly check the battery, control box and cables to make sure they’re in good condition. Keep an eye on the data from the app too to make sure everything is in good working order.
How to make a solar battery last as long as possible
The last thing you want with your solar battery is a premature replacement. To avoid this, it’s important to keep a few things in mind to help your battery last as long as possible with maximum efficiency.
Firstly, get it installed in the correct place. You want somewhere cool and dry with good ventilation. Keep your battery away from extreme conditions and moisture where possible.
Once in place, it’s a good idea to conduct regular charge and discharge cycles. You might think this sounds obvious as you’ve invested in the technology, but running too many or too few cycles can cause problems with the lifespan.
It’s standard procedure to go through one cycle per day. This will help keep your battery in good condition, without causing excessive wear and tear or leaving it without charge for too long.
Make sure you’re aware of the manufacturer’s guidelines when it comes to DoD. If you drain the battery completely each time, you’ll negatively impact its performance over the long term.
And finally, routinely check the physical state of your battery, as well as the data produced from your app. This should tell you how the battery is performing and if there are any problems.
What’s the warranty on a solar battery?
A standard warranty covers all defects and breakdowns provided the battery is used as intended. Most solar battery manufacturers offer 10 year warranties. This is true for popular batteries, such as the Tesla Powerwall 2, Huawei Luna and LG Resu.
Some brands who are super confident with their product have extended their warranties. GivEnergy’s All in One solar battery offers a 12 year warranty and the Enphase IQ offers a substantial 15 year warranty (or up to 6,000 cycles).
When manufacturers stipulate a maximum number of cycles, it’s usually to cover themselves from overuse by the owner. Warranties may also detail a guaranteed retention of capacity. This explains that the battery will maintain up to a certain amount of its original capacity over the warranty span. For instance, if a customer purchases a 10 kWh solar battery, the warranty typically states that it will retain at least 7 kWh of its initial capacity for the length of the warranty.
Here are the warranties of some of the most popular brands:
- Enphase IQ – 15 years
- Giv Energy All in One – 12 years
- Tesla Powerwall 2 – 10 years
- LG Resu – 10 years
- Huawei Luna – 10 years free, option for 5 year paid extension
How do I know when my solar battery needs replacing?
There are a few key indicators to tell you when a solar battery needs replacing. This isn’t to say your battery will need replacing as soon as you notice a change, but it’s something to bear in mind as you get to the 10 year mark.
- Change in charging times – If the battery consistently takes longer to charge, this could be an issue. On the flip side, a battery that charges up slowly is a sign of reduced storage capacity. This usually goes hand-in-hand with a faster discharge rate than expected.
- Quickly depleting charge – A noticeable reduction in how long the battery maintains power supply compared to its past performance suggests it’s time to consider a replacement. We see this all of the time with our phones and laptops, except a solar battery is on a larger scale.
- Visible damage – Any signs of leakage or corrosion isn’t good. Get these checked out as soon as possible by a professional as they may provide a safety risk.
How long does a fully charged battery last before it’s depleted?
You might also be wondering how long a fully charged battery lasts for before it’s depleted?
This comes down to three main factors:
- Storage capacity of your battery
- Your electricity use
- Whether your battery is paired with solar panels – check out this post on solar panels with or without battery storage
Battery size is characterised by two main components: stored capacity (measured in kilowatt-hours or kWh) and power output (measured in kilowatts or kW). This is distinct from the physical size dimensions of battery storage.
Most standard home battery systems have a capacity between 5 and 10 kWh, with power outputs ranging from 3 to 8 kW. Larger batteries with higher capacities will naturally last longer before depletion. Learn more in our post on what are battery energy storage systems.
The average UK household consumes 6-10 kWh of electricity per day. So generally speaking, you can expect to get around one day of use from a fully charged storage battery. If you have a larger 12kWh battery but only use 6kWh of electricity per day, you’ll get around two days use on a full charge (assuming a 100% DoD).
Of course, the more electricity you use, the faster your battery will deplete. High-energy appliances, such as tumble dryers, washing machines and electric ovens, will drain the battery more quickly than lower-energy devices like light bulbs, kettles and phone chargers. This is why it’s always worth getting energy efficient appliances to reduce your electricity use and costs.
The weather conditions can make a difference. When a battery is paired with solar panels and the conditions are sunny, your battery can be replenished during the day. In this instance, a fully charged solar battery can keep essential home functions running for a couple of days. However, this timeframe will vary for each home depending on actual daily energy usage.
And there you have it. A good quality solar battery should last you at least 10-12 years, if not pushing up to 15 years. With solar panels lasting around double the amount of time as batteries, it’s likely you’ll need to buy two batteries over the total PV lifespan.
