1. Lifespan beyond 5000 cycles (equals to 10 - 15 years):

When you discharge a battery (use it to power your appliances), then charge it back up with your panels, that is referred to as one charge cycle. We measure the lifespan of batteries not in terms of years, but rather how many cycles they can handle before they expire.

Many see the price tag of lithium batteries and immediately walk away. However, one of the most important aspects to consider is how long they last. Normal lead-acid batteries can last anywhere from 200 to 900 charging cycles under ideal conditions with proper maintenance. This ends up being around 5 years at most with daily solar charging.

On the other hand, lithium batteries are known for lasting 5000+ charge cycles, translating to 10+ years of use. They come with a high investment but will last you years longer. Not needing to replace lithium batteries as often makes them one of the most cost-effective options for a solar power system battery bank.

2. Depth of Discharge

Discharge depth refers to how much overall energy  capacity is used before recharging the battery. For example, if you use a quarter of your battery’s energy capacity, the depth of discharge would be 25%.

Batteries don’t discharge fully when you use them. Instead, they have a recommended depth of discharge: how much can be used before they should be refilled.

Lead-acid batteries should only be run to 50% depth of discharge. Beyond that point, you risk negatively affecting their lifespan.

In contrast, lithium batteries can handle deep discharges of 80% or more. Meaning that they feature a higher usable capacity.

3. Efficiency

Lithium batteries are more efficient. This means that more of the solar power you harvest is stored and used.

For example, lead acid batteries are only 80-85% efficient depending on the model and condition. That means if you have 1,000 watts of solar coming into the batteries, there are only 800-850 watts available after the charging and discharging process. The rest of the energy is lost in chemical reactions within the battery.

Lithium batteries are more than 95% efficient. In the same example, you’d have over 950 watts of power available.

Higher efficiency means your batteries charge faster. Depending on the configuration of your system, it could also mean you buying fewer solar panels, less battery capacity and a smaller power backup inverter.

4. Faster Charging Rate

With higher efficiency also comes a faster rate of charge for lithium batteries. They can handle a higher amperage from the charger, which means they can be refilled much faster than lead-acid.

Lead-acid batteries are limited in how much charge current they can handle, mainly because they will overheat if you charge them too quickly. In addition, the charge rate gets significantly slower as you approach full capacity. in some cases more than 2x as long as a Lithium alternative

5. Energy Density

The energy density of lithium batteries is much higher than lead-acid, meaning that they fit more storage capacity into less space.

As you can see in the picture above, it takes one lithium battery to power a 5kW system, but you’d need 8 lead-acid batteries to do the same job. When you take the size of the entire battery bank into account, lithium weighs less than half as much.

This is a real benefit especially if you don't have much space to work with. Lithium batteries can even be mounted on a wall as seen in the picture below.