Lithium-ion vs Lead for Off-Grid Energy
What makes lithium-ion a game changer for off-grid energy storage?
In recent years there have been many off-grid energy systems on the market with outdated, over sized, and under powered lead-acid batteries. Lead-acid batteries work as designed for a few years if you're lucky, but then they start to lose their depth of charge- impacting the overall effectiveness of the energy system and possibly rendering it useless.
The good news it that we're currently in a transition period between lead-acid batteries, the tried-and-true technology used for decades, and lithium-ion’s promise of better discharges, higher density, improved resiliency, no maintenance, and longer cycle life. Many experts predict within the next 10-15 years society will move away from lead-acid batteries entirely.
But what about the future of lead-acid batteries? They’ve been around for such a long time that they are practically a commodity. Lead-acid battery quality ranges significantly depending on the manufacturer, but the technological differences are minimal. Manufacturers have been running the industry for what seems like forever, so why disrupt this two-century old technology?
Lithium-ion is superior to lead-acid in size and weight
While superior energy density is not critical for stationary applications, it's essential for electric vehicles and portable electronics. Increased energy density greatly improves the deployment and installation process for stationary energy storage.
Lithium-ion batteries are in a league of their own when compared to all other battery types since they are significantly more energy dense.
Undeniable resilience in most environments
It's common knowledge that any battery is vulnerable to damage from excessive discharging and extreme temperatures, but lead-acid batteries are generally less resilient to this kind of abuse and are irreversibly damaged if discharged too quickly or deeply. Usually once this happens they never will perform the same way as before. Lead-acid batteries lose potential cycles if they're discharged below 50% of their state of charge or if discharged faster than C/8. On the other hand, lithium-ion batteries can be discharged to about 80% SOC and at a rate of C/2 without any long term damage. They'll also continue to flow power consistently the entire time.
An easy way to put this into a regular everyday situation of charging and discharging a battery is to think of it like a balloon. If you repeatedly inflate a balloon to its highest capacity and then completely deflate it, the balloon material will certainly fatigue from the massive stress. Next, imagine this with another balloon you repeatedly inflate and deflate it from 50% to 90% full, the material will experience less stress on it and will last longer than the first balloon by leaps and bounds due to lesser impact on the materials. The plates inside the battery undergo the same type of stress as the balloon material. In this example, lithium-ion batteries are simply made from a better, stronger material when compared to a lead-acid battery.
Besides the depth of discharge benefits, lithium-ion batteries have a significantly longer useable life. They can sit idle for an extended period of time and only lose a fractional charge because the self discharge factor is very small.
Yes, it's certainly true that the initial cost of lithium-ion batteries is higher than alternative batteries. Since lithium-ion is a newer technology and less abundant than lead, it's also not likely that the price will reduce in the near future. However you have to ask this, is it fair to compare batteries by the initial price tag and the rated capacity? That is a definite NO!
While the initial cost of a battery is important to consider when budgeting for an off-grid energy system, it's important to note that a more expensive battery will save more money in the long term. Lithium averages roughly six times the number of charge cycles compared to lead-acid.
If lead acid batteries get discharged past 50% frequently or if the maintenance is not handled appropriately, then they will have a very short life span. Lithium-ion batteries require very little to almost no maintenance and are more resilient to irregular discharging. When utilized properly, these factors definitely make lithium batteries more appealing for an off-grid solar energy system.
Lithium-Ion is the champion of the future
For what feels like forever, lead-acid batteries have been the winning choice for off-grid solar systems. With the growth of electric vehicles and portable energy storage solutions, lithium-ion battery technology has improved vastly and become the top option for off-grid solar.
In 2016, lithium-ion batteries were just beginning to be used for large-scale solar systems, but they have been used for portable and handheld solar systems for years. Due to their enhanced energy density and ease of transport as well as smaller size and reduced weight, you need to look at using lithium-ion batteries when planning a portable solar energy system.