What is the life expectancy of a solar battery?

How many years will your solar battery last? And what will warranty cover?

Solar panels can be a big investment for your home. A good solar system should last for 20 to 30 years. Whereas, the lifespan of commonly available Lithium-Ion solar batteries lasts from 5 to 15 years

The life span of the battery is affected by several factors. Some of these factors are explained below to make sure that you get the most value out of solar batteries. 

How often a battery is used

How long a battery lasts depends less on the number of years it has been installed, but rather on the number of “Battery Cycles”. The “Battery Cycle” is the number of times the battery goes flat and recharged to full again. 

Batteries generally degrade after every cycle. Degradation occurs slowly at the start of the battery’s life but it gets much quicker at the end. Due to the effect of degradation, the battery loses its ability to hold a charge. After every cycle, the discharge of the battery becomes faster and faster. In the end, this degradation becomes so significant that the battery won’t be able to hold a charge long enough for it to be useful. 

Depth of Discharge

A battery’s depth of discharge (DoD) indicates the percentage of the battery that has been discharged relative to the overall capacity of the battery.

If you want to extend the life expectancy of your solar battery then you should focus on the manufacturer’s recommended DoD. For example, if the recommended DoD by your battery’s manufacturer is around 90%, then you should not drain the battery past the 90% mark. Fully drainage of the battery every time reduces your battery’s life expectancy.

For example, the DoD of the Redback sb7200 is 90%. Here’s a screenshot from the datasheet.

Seeing as the Maximum Capacity is 7.2kWh, the manufacturer does not recommend the battery being discharged past 90%, which is 0.72kWh.

The partial discharge cycle gives the best value. If you charge 20% or 30% of your battery then you can improve its lifetime. If you want the best results, try not to fully charge your battery to 100%.  

Battery Maintenance

Battery maintenance is an important factor in estimating the life expectancy of a battery. If the proper maintenance is not provided to the battery then it is possible you end up with a broken battery in a very short time. 

Lithium-ion batteries have a very simple maintenance procedure. Once in a while check a ‘State of charge reading’. This will update you about the state of the battery and whether it is holding the charge properly or not. Next, check the cables and terminals to make sure that everything is secure and tight. Lastly, dust off the battery so that it does not produce any extra heat. 

Solar Battery Temperature

Solar battery temperature is an important consideration in determining the lifespan of a battery. Both the extreme hot and extreme cold situations are not good for batteries. A temperature-controlled space is the best place for a solar battery. 

However, if the temperature conditions are extreme in your area then you should install your solar batteries in a garage or in the basement. Here’s a look at the best place to locate your battery

Solar Battery Warranty

You should be aware of your battery’s warranty to get more value out of the battery. If something becomes faulty then you can claim your warranty to get a replacement of your dud battery. Usually, manufacturers offer warranties of 10 years or more.

Goodwe technologies provide a performance warranty of 10 years. During this period, the battery either retains 70% of usable energy or for a Minimum Through Output Energy.

Redback technologies also offer a 10 years warranty. During this period if any redback product becomes faulty then Redback will repair the defective one free of cost. 

Does leaving the battery on max charge affect life?

The charging of lithium-ion batteries stops once it reaches 100% of its capacity. But if you are continuously charging batteries on max then your batteries will constantly bounce between ‘full charge’ and a ‘little below full charge’. This trickle leads to higher ambient temperature, thus affecting the battery's capacity. If you keep on charging them and leave them on max charge then the overall lifespan of your batteries will reduce dramatically.  

Does leaving the battery on the flat for a long time affect life?

If you are leaving the house for a long time then you should switch off the solar battery systems. Uncharged batteries for a longer period of time are not beneficial for the lifespan of batteries. Always make sure that your charging source is ‘on’ to charge the batteries continuously. Leaving batteries uncharged can bring damage to them. This can reduce the capacity of the battery significantly.

If you are planning to store your battery (un-used), then you should first discharge the battery around 40% to 50%. Thereafter, you should recharge your battery every 3 to 6 months to avoid any deterioration of cells. 

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