The main difference between Lithium and Lead Acid batteries are the metals used to manufacture them. With this difference come the differences in lifetime, performance, and price. Both batteries have their benefits and drawbacks.
It is important to compare these two batteries against different parameters to choose which battery type is the best when investing in solar energy systems, especially ones with solar panels. Some important aspects to keep in mind when choosing a battery type for solar energy are:
Size and Weight
Lithium batteries are preferred to Lead Acid batteries when it comes to storage. Lead batteries are bigger and heavier, they require a lot of rack space to be installed and are difficult to move or relocate.
Rate of Charge
Usually, the greater the battery´s efficiency, the higher its charge rate. Lithium batteries have a higher charge rate than Lead Acid batteries. Lead Acid batteries take longer to charge (in some cases more than twice the charging time of Lithium batteries). They can't handle as quickly of a charge supply as Lithium alternatives because they overheat.
Lifespan
Batteries, like solar panels, deteriorate with time and become less effective as they age. Generally Lithium batteries last longer than Lead Acid alternatives.
Efficiency
Battery efficiency is an important aspect to consider when comparing Lead Acid and Lithium batteries for solar energy. Batteries with more efficiency charge quicker and have a better battery capacity. At least 95% of the solar energy stored in Lithium batteries is actually usable while a Lead Acid battery has around 80-85% efficiency. Therefore, Lithium batteries are more efficient and can be used to discharge more solar power. Higher efficiency can also imply buying fewer solar panels and a smaller backup generator.
Depth of Discharge
Depth of Discharge of a battery is the precentage of solar energy in the battery that can be drained safely without causing harm to its internal functioning before recharging the battery. A Lead Acid battery should be drained no more than 50% because more than that has negative consequences on the battery, while it is safe to use 85% or more solar energy from a Lithium's total capacity. This means that Lithium batteries have a greater effective capacity compared with Lead Acid batteries, making them a better choice.
Battery Capacity
The capacity of a battery measures how much solar energy can be stored, and eventually discharged by it. Usually, Lithium batteries have a greater capacity than Lead Acid batteries. This means that more solar energy can be stored in a Lithium battery that is the same size and shape as a Lead Acid battery. If you can store more energy, you can also discharge more. Therefore you can supply solar power to your appliances for more time.
Price
When comparing prices, Lead Acid batteries are a better choice for solar storage. A Lead Acid battery system for solar storage costs less than a Lithium battery system of the same capacity and size. However, taking into account the rest of the comparisons mentioned above, even though Lead Acid batteries generally have lower initial costs, the lifespan value offered by Lithium batteries is better long-term.
Which Batteries are Better?
In terms of lifespan, efficiency, discharge depth, and capacity, Lithium batteries are better. However, they are more expensive than Lead Acid batteries. In conclusion, go with Lead Acid batteries if you are looking to power normal household appliances through solar energy. Lithium variants are the way to go if you want long-term, reliable, batteries that can power many appliances at once with solar energy.