Lithium iron phosphate batteries are designed for a long lifespan with heavy cycle usage, making them a major improvement on many of their predecessors.
In the past two to three years, lithium battery cells have dropped in price significantly, making them as affordable as other battery options but with much better value.
Even with this lower price, batteries are still around half the cost of your solar system, so it is well worth looking after them.
Temperature
Lithium batteries are not fond of low or high temperatures. Generally speaking, here in New Zealand, it is not a major concern, as we have mild temperature ranges.
The main rule of thumb is that if you are going to have ambient temperatures below zero degrees Celsius regularly, you should keep your batteries inside or have some sort of heating system for them.
This could be internal to the batteries, which is common in grid-tied systems designed to sit outside, or it could be that the cabinet they are mounted in has a heating unit.
Cycle Use
Lithium batteries, particularly LiFePO₄ batteries, are designed for many charge and discharge cycles with minimal capacity reduction. This makes LiFePO₄ cells the most popular choice for off-grid systems today.
Although they already have a long life, you can extend it further with proper care.
This type of battery wears faster when fully charged and fully discharged. The most common way to reduce this extra wear is to keep the battery between 20% and 80% charged, as we do in our systems.
This may mean you have slightly less storage to work with, but the prospect of an extra three to five years of service life makes it a worthwhile choice.
Storage
Solar Lithium batteries have a very low self-discharge rate when not in use, so they can last a long time in storage. However, keep in mind that lithium batteries, like all batteries, not only wear down with use but also have a calendar life.
It is best to purchase them as close as possible to when they will be used. Storing them for an extra two to three years, for example, will take a small amount of time off the end of their service life.
If you do have to store them for some time, make sure to charge them to around 75% before leaving them. It is also worth checking on them every six months and keeping them topped up to that level.
Upgrading
If you want to add more batteries to your system later, you will need to consider that batteries of different ages will have different capacities and capabilities. If you add a new battery alongside significantly older ones, the newer battery can end up working harder to compensate.
Fortunately, solar lithium batteries are generally slow to lose capacity, so the window in which you can mix batteries is much longer than with lead-acid batteries. They are also configured in a way that reduces voltage imbalance issues, so problems are far less common.
With our batteries, for example, we recommend upgrading within one year, with an absolute maximum of two years.
Conclusion
Hopefully, this helps you get the most out of your solar lithium batteries. All advice here is relatively general, so for any specific questions, please get in touch with the team here at GridFree. We are always happy to help.
Have a look at our solar packages that include Lithium Batteries: The Pro Series, The Solar Nest Series