Lead Acid vs Lithium Batteries: Which Are Best For Solar Storage?
Battery systems for solar storage are starting to become an increasingly common addition to the solar energy set-ups of usual households.
Two of the most common battery types are Lithium batteries and Lead Acid batteries.
With the difference in the constituent metals used to manufacture the batteries, comes the differences in cost, performance, and lifespan.
Both Lithium and Lead Acid batteries have their individual benefits and drawbacks.
When it comes to investing in solar energy systems, especially the ones with solar panels, it’s important to compare these two battery types against various fitting parameters to decide which type of batteries are the best — Lithium or Lead Acid.
Here are some decisive comparison details to bear in mind when choosing a battery type for storing solar energy:
Cost
In regards to cost, Lead Acid batteries are a better choice for solar storage.
A Lead Acid battery system for solar storage costs much less than a Lithium battery system of the same size and capacity.
However, even though Lead Acid batteries usually have lower initial costs — that is, both pricing and installation charges, the lifetime value offered by Lithium batteries is better in the long run.
Battery Capacity
The capacity of a battery measures the amount of solar energy that can be stored, and eventually discharged by it.
While the exact capacity varies from battery-to-battery, and also depends on the model and manufacturing company; generally, the Lithium batteries massively outperform the Lead Acid counterparts in this aspect.
It is well established that Lithium batteries have a notably higher energy density than Lead Acid batteries. This implies that more solar energy can be stored in a Lithium battery having the same shape and size as that of a Lead Acid battery.
And, since you can store more solar energy, you can also discharge more of it. Hence, you can supply solar power to your appliances for a longer stretch of time.
Depth of Discharge
Depth of discharge of a battery is the percentage of the solar energy in it that can be safely drained without causing any damage to its internal functioning.
In other words, discharge depth is the overall capacity that can be harmlessly used before recharging the battery.
It is safe to use 85% or more solar energy from a Lithium battery’s total capacity, whereas a Lead Acid battery should not be drained of solar power by about 50%, as doing so has negative consequences on the life of the battery.
The higher depth of discharge achievable with Lithium batteries means that they have a greater effective capacity as compared to Lead Acid alternatives, making it preferable.
Efficiency
Similar to solar panel efficiency, battery efficiency is also a significant parameter to consider when comparing Lithium and Lead Acid batteries for solar energy storage.
Batteries higher in efficiency get charged quicker and have more effective battery capacity.
Lithium batteries are usually 95% or more in terms of efficiency, which means that 95% + of the solar energy stored in them is actually usable.
On the other hand, a Lead Acid battery has about 80 – 85% efficiency.
Hence, Lithium batteries are more efficient. This signifies that you can use them to discharge more solar power.
Depending on your specific arrangements, higher efficiency also implies that you need to buy fewer solar panels and a smaller backup generator.
Lifetime
Batteries are similar to solar panels in the aspect that both deteriorate as they age and become less effective over time.
The lifespan of a battery isn’t counted in years but the number of cycles.
Discharging a battery of solar power to run your devices and then recharging it with solar panels counts as one “cycle”.
Lithium batteries, in general, last several times the number of cycles longer than Lead Acid batteries. This means Lithium batteries have a much longer lifespan as compared to Lead Acid ones.
Rate of Charge
Going by the general rule, the greater a battery’s efficiency, the higher is its charge rate.
Thus, Lithium batteries have a higher charge rate than Lead Acid batteries
Lead Acid batteries can’t handle as quickly of a charge supply as Lithium alternatives, mainly because they overheat when being charged too quickly.
Lead Acid batteries take significantly longer to charge, which in some cases can be more than twice the charging time of Lithium batteries!
Size and Weight
Lead Acid batteries require a lot of rack space, as they’re usually bigger in size and need more free area to be installed in.
Thus, if space is a consideration, Lithium batteries are preferred to Lead Acid batteries for solar storage.
In addition to being bigger, the Lead Acid batteries are also cumbersome.
They’re much heavier and difficult to move or relocate as compared to Lithium batteries.
Such inefficient physical characteristics may add to the labor, installation, and replacement charges.
Finally, Which Batteries Are Better?
Lithium batteries are better in terms of battery capacity, discharge depth, efficiency, and lifetime. However, they’re much costlier when compared to Lead Acid batteries.
Thus, if you’re looking to power usual household appliances through solar energy, go or Lead Acid variants.
But, if you want a reliable, long-term battery that can power loads of appliances at once with solar energy, Lithium batteries are the way to go!