How Long Do Solar Batteries Last? [A Guide]

As the energy and climate crises worsens, now more than ever we’re looking to invest in residential green energy, with the most popular and practical option being solar, but there’s a small catch…

Solar energy may be 100% renewable, but the batteries we use to hold the charge they generate are only reusable up to a certain point.

Like any electronic device, they will slowly degrade and eventually give up the ghost.

If we’re to continue to harness solar energy rather than use it in real-time as it’s generated, we’ll need to replace that spent battery.

But how long can you expect such a battery to last, and do they expire quickly enough to offset the gains you’re making on the free energy? Let’s find out!

What Is A Solar Battery

Before we dive into some cycle lives, let’s briefly discuss what solar batteries are.

Solar batteries are simply batteries integrated into a solar power system, enabling it not only to use solar power, but to store it for use at a later date, and they’re essential if you’re trying to establish a home or mobile backup system.

But these nifty power storage units have uses outside of emergencies.

By collecting all the energy that isn’t used in the moment, they cut solar waste to an absolute minimum, ensuring you’re getting your money’s worth out of that expensive panel array.

In fact, they can actually start to make you money if your panels are producing energy in excess, as you can sell it back to the grid.

How Long Will My Solar Battery Last?

It’s impossible to put a single shelf life on all solar batteries, as there are simply too many variables involved, but generally speaking, you can expect your battery to last between 3 and 10 years, maybe even 12 to 15 in certain scenarios.

To estimate a lifespan for your battery specifically, we need to think about the following:

Battery Technology

There are two common battery technologies used for solar power storage, lithium ion and lead-acid. Lithium is the golden boy of the solar battery world right now.

This type of battery is more efficient in a number of ways. They hold more power for longer, they’re lighter and a lot smaller, and they have beefy cycle lives.

This LiFePO4 solar battery, for example, will run for 10 years. Lead-acid batteries can be great as well, but, generally speaking, they don’t last quite as long.

Battery Quality

We also have to consider the production quality of a solar battery before approximating its lifespan.

In fact, in many ways, battery quality is more important than battery technology, as a well-made lead-acid product will outperform a poorly made lithium battery.

Not to say there aren’t some great deals out there, but with solar batteries, by and large, you get what you pay for.

The more you invest, the more you stand to benefit and save in the long run — it’s always best to buy quality.

Maintenance & Care

Many solar batteries are marketed as “maintenance-free” devices, and for lithium models, there is some truth to that statement, but all batteries need some TLC over a long enough period.

For lithium ion solar batteries, you’ll mostly just have to keep tabs on thermals, providing protection in the event of extreme weather conditions.

You should also make sure you pay attention to the depth of discharge (DoD) threshold, as allowing it to run dry beyond that point will cause stress and diminish overall service life.

You have to be far more hands-on with lead-acid batteries. They require…

Rotation

If you’re linking up a number of lead-acid batteries in order to amass a few days’ worth of backup power, you’ll need to rotate the batteries in the circuit in order to maximize their lifespan.

This is because certain points of the circuit have to work harder, which of course triggers premature degradation.

Frequent Charging

Much like lithium batteries, lead-acid batteries need to be kept charged to a point or their performance will dip quicker than usual. They also need to be charged up before storage.

Distilled Water

Deep cycle batteries require a liquid in their cells to facilitate optimal performance and service life, but you should only ever use distilled water. Anything else will harm the battery’s lifespan.

Ventilation

When lead-acid solar batteries approach full charge, they start “gassing”, which means they expel hydrogen gas and water, and as hydrogen can be very dangerous, your battery bay needs to have adequate ventilation.

Equalization

As well as rotating your lead-acid solar batteries, you’ll need to equalize them, which basically means you’ll carry out controlled overcharges.

This is necessary as the charge throughout the circuit will be uneven, meaning certain parts will not reach full capacity, which, over time, can limit performance and lifespan.

Installation

No matter how good your solar battery is, if the installation is subpar, it’s likely not going to last as long as it could.

Thankfully, it’s not a difficult job for a trained electrician, and it doesn’t involve any complicated roofing issues like the installation of solar panels does.

Realistically, the only time an installation may go wrong is when it’s done DIY, but that’s not to say you shouldn’t give it a try and save some money.

As long as you have experience in the area, and you have a good idea of what you’re doing, you’ll be fine. If you’re not feeling confident, don’t hesitate to call a professional.

How Long Will A Lithium Ion Solar Battery Last?

High quality lithium ion solar batteries often come with a warrantied lifespan of 10 years, minimum or 10,000 charge cycles.

Whichever milestone is reached first signifies the end of the warranty period.

It’s not unheard of for lithium ion solar batteries to reach the 15-year mark, and as they’re far more efficient, they can really save you some money over that period.

How Long Will A Lead-Acid Solar Battery Last?

If we’re talking averages, you can expect your lead-acid battery to last between 3 and 5 years. But if you take good care of it and it’s well crafted, it may just reach the 10-year mark.

The real benefit of lead-acid batteries is the price tag.

Although lithium batteries are more efficient, many opt to increase their solar yield by investing in multiple lead-acid batteries and linking them up.

This will give you more capacity on a per-dollar ratio, but the intensive maintenance schedule is a deal breaker for a lot of solar enthusiasts.

Final Thoughts

Trying to figure out how long a solar battery will last is tough, as there are a number of factors to consider, but generally speaking, service lives span from 3 all the way through to around 12 years, with some holding out even longer.

Your maintenance routine will play a huge role in the overall cycle life, so be sure to be kind to your battery in any way you can, and if you can afford it, choose a premium product.

Perhaps the easiest way to gain an understanding of a battery’s potential lifespan is to assess the warranty.

Many batteries will be warrantied up until a certain period of time, meaning your battery is pretty much guaranteed to last that long.

Do bear in mind though that even the very best lithium ion solar battery will need to be replaced at some point, as solar panel systems tend to last between 20 and 30 years.

Thankfully, the money you’ll have saved on energy in that time will pay for a new battery many times over.