How Long do Solar Batteries Last?

Installing a solar power system gives your home almost free energy for years. But it also requires some time-to-time maintenance and replacements. Like solar panels and solar inverters, solar batteries also have a limited lifespan. With time, solar batteries keep losing their efficiency and eventually need to be replaced.

Most solar batteries work for more than 5 years; some can work for up to 15 years. The lifespan of a solar battery depends on certain factors like its composition, use, maintenance and environment. With proper care, the lifespan can be enhanced.

On a commercial scale, the life of a solar battery is considered in two aspects, its useful life and its warrantied life.

Useful Life of a Solar Battery
Until the storage capacity of your battery drops below 60% of its nominal storage; it is in the useful life. Even though it will not work as well as a brand-new battery, it will still serve the purpose to some extent. However, below this point, the battery has nearly reached the end of its life.

Warrantied Life of a Solar Battery
Every branded solar battery comes with a warranty. The company guarantees to replace the battery or compensate if the battery reaches the end of its life before the warrantied period ends. This warrantied period is the warrantied life of the solar battery.

Typically, the warrantied life varies from 1-20 years depending on the brand and the type of battery. Once you have purchased the battery, its warrantied life starts and expires after a certain period, even if it functions well.

As mentioned, the company replaces or compensates for the battery if it expires before its warrantied life ends. However, every brand mentions some conditions that must be complied with to claim a warranty. These conditions include the cycles used and maintenance.

Factors That Affect The Life of Solar Batteries
Let’s discuss all the reasons that cause the loss of solar batteries and affect their life.

Type of Battery
You might already know batteries exist in many types. Each type has its advantages and limitations. Similarly, their lifespan also varies concerning their use in solar power applications.

Lithium-ion Batteries
Lithium-ion batteries have the longest life among all the commonly used batteries. They also consume less space, require no maintenance and are lightweight, making them ideal for use in products with weight and size limitations. However, they are also expensive, which makes them less suitable for use at home, especially if you are on a budget.

Saltwater Batteries
Saltwater batteries also have a long lifespan and are cheaper than lithium-ion batteries. So, they are a good match if you are on a budget and looking to buy long-lasting batteries.

Lead-acid Batteries
Lead-acid batteries have the shortest lifespan among all the types mentioned. They work for just 3-5 years, depending on other factors. However, they are also the cheapest. So, they are suitable for short-term usage.

Life Cycles
Solar batteries have a limited number of life cycles. Every time a solar battery completely charges or discharges, it counts as one life cycle. So, once the number of life cycles has been completed, the battery deteriorates and reaches the end of its life.

Since life cycles depend on full charging and full discharging, they can be avoided if a battery is not frequently fully charged or fully discharged. This is where a good solar inverter plays its role, and its charge controller ensures the battery’s life cycles are unaffected.

But does a battery never expires if it is not frequently charged or discharged? No, the battery will still expire sometime (depending on the frequency of usage).

Another important detail to note is that most batteries’ life ends with the completion of their life cycles, even if they are in warrantied period.

Depth of Discharge (DOD)
The DOD is the limit a battery should be discharged to maximum. If a battery is drained beyond the DOD, it severely affects its life. For example, most lead-acid batteries have a DOD of 50%, which means they shouldn’t be discharged below 50% of their storage capacity. Similarly, a lithium-ion battery has a DOD of 15%; it shouldn’t be discharged below 85% of its storage capacity.

Frequent discharging beyond DOD also void its warranty.

Energy Throughput
Throughput is the total energy passed through a battery in terms of charging and discharging. It is directly linked to the frequency of use. The life cycles and DOD have no impact on the energy throughput. So, every time you use your battery, it deteriorates a bit. Excessive use will end its life before time.

Once the throughput of a battery exceeds the specified throughput of the battery on its warranty details, it is no longer under warranty, no matter if it is in the warranty period.

Battery Capacity 10 KWh
Useful Capacity 9.48 KWh
Energy Throughput Limit 24,770 KWh
Throughput Cycles 2950
Total life (If charged once a day) 8.08 years

Solar batteries are sensitive to the temperature in their surroundings. Extremely high or low temperature affects their life. The chemical reactions happen more than usual, resulting in higher wear and tear.

Moreover, if a battery operates at extremely low temperatures, it also discharges faster than usual. Extremely high temperatures can cause hazards. Consider the nominal temperature range specified on the battery’s specifications to ensure it lasts long.

Some batteries require routine maintenance, which helps them last longer. For example, the water level of flooded lead-acid batteries must always be maintained. If their water level drops below the specified point, they may not function well, affecting their life. On the other hand, sealed lead-acid and lithium-ion batteries do not require any such maintenance.

Sometimes, the chemical inside flooded Lead-acid batteries also falls below the necessary quantity and needs to be maintained. If not filled in time, it can affect the life of the battery..

How Can You Make a Solar Battery Last For Long?
Even though every solar battery expires after a while, there are ways to slow down its deterioration. I have listed below some tips.

Choose a Suitable Battery
If you are going to put the battery to excessive use and utilize most of its storage capacity, a Lithium-ion or a Saltwater battery may be a more suitable option than a Lead-acid battery. However, if you do not require excessive use for long, a Lead-acid battery will also work fine.

But if you cannot maintain the battery’s water level or need a lot of energy storage and have limited space, choose a lithium-ion battery.

Keep the Battery Charged
Solar batteries shouldn’t be kept discharged for long; they must be charged even if they are not in use.

Avoid DOD and Never Completely Charge or Discharge
Make sure the DOD is not compromised and the charging and discharging limits mentioned on the battery’s specifications have complied.

Maintain Your Battery
If the battery requires maintenance, like water level, ensure it is regularly checked and maintained.

Ensure Your Inverter Works Fine
The charger controller of your solar inverter directly impacts the life of your battery. If it works well, your battery will last longer. Get it checked by a certified professional once in a while.

Final Thoughts
Always choose a solar battery after assessing your need and the battery’s specifications. Also, ensure it is compatible with your solar inverter and get it installed by a professional. Comply with the instructions specified by the brand, and your battery will work just fine.