For many years, lead acid batteries have been the most dominant battery technology used in solar energy systems. However, in the few recent years things are starting to change as a good number of people are now opting for Lithium batteries. Those still using Lead acid are mainly the people who can not afford lithium batteries.
Lithium batteries have so many advantages over Lead acid and some of these include;
- They have a higher depth of discharge. Depth of discharge (DOD) basically represents how much you can drain the battery before it starts losing its overall charge capacity. Most lead acid batteries can not be drained beyond 50% where as a lithium battery can be drained even up to 0% though it is not advisable
- Lithium batteries are also more durable. Lithium batteries are more durable and they also have more charge cycles than Lead acid batteries. With all factors constant a Lithium battery can be used for almost twice or thrice the time you will normally use a lead acid battery
- Low maintenance costs: In normal circumstances, you will spend almost nothing to maintain a lithium battery apart from regularly cleaning the battery when it is dusty. On the other hand, lead acid batteries will require changing the acid after a certain period of usage. This makes lead acid batteries more costly in the long run
There are several other benefits that lithium batteries have over lead acid but the above are the major ones. The only downside with lithium batteries is their initial cost being high. However, this is changing as more research is now being done to reduce the cost of these batteries.
What type of battery is best for solar panels?
There are several batteries that can be used to store energy from solar panels. The choice one makes will mainly depend on their power requirement, how long they'll use the solar energy and whether solar is being used as the main source of energy or an alternative when grid-power is off.
Some of the common types of battery technologies used to store solar energy include Lead Acid batteries, NICAD batteries, NIFE batteries and Lithium batteries. With all factors constant, the best battery technology amongst all these is Lithium. It is more durable, has more charge cycles and also has a round trip efficiency of up to 98%.
The main reason people opt for other battery technologies is mainly because of the initial cost of the Lithium batteries. If we compare Lithium and lead acid batteries, you will realize that Lithium batteries are almost 3 times more expensive than lead acid batteries. So, people who don't have big budgets and those who want to use solar for a short period of time will always opt for the cheaper option which obviously lead acid.
Can you charge a lithium battery with a solar panel?
Yes, solar panels can charge a lithium battery and, in the end, that charge is stored in these batteries. However, you will need a charge controller to do this. The energy from the solar panel can only be converted to the suitable voltage that can be stored in the battery after passing through charge controller.
Charge controllers are designed for specific types of batteries. For instance, a charge controller designed for a lithium battery cannot be used to charge a lead acid battery. This is because charge controllers are designed to output a particular voltage for a specific battery technology. The charge algorithms of the charge controllers also vary. So, using a different type of charge controller has a lot of safety risks that you need to avoid at all costs
The good charge controllers of Lithium batteries normally have a protection circuit that automatically stops charging the battery when it is full. So, you won't have cases of overcharging which is a common thing among lead acid batteries. If the protection circuit is not present or has some fault, the battery may end up being overcharged that may lead to overheating and in some situations the battery may catch fire.
What performances does a solar battery need?
Before buying a solar battery for your system, there are major performance parameters you need to look at. But first of all, before analyzing the performance parameters, it is always recommended to look at your power needs. It's from these needs that you will derive the battery features you need.
Some of these performance parameters include the following
- The battery power: This is the amount of electrical energy that the battery can provide at a time and it is measured in watts(W). Make sure you buy a battery that has a slightly higher power output than the total power you'll need in your house
- Battery capacity: The capacity of the battery basically represents the amount of electrical energy a battery can be able to store. Battery capacity is normally measured in Ampere Hours (AH). The good thing with batteries, one can add more batteries in future to increase the capacity in case they need more.
- Depth of discharge (DOD): DOD represents how much of the battery capacity you can use without affecting the overall capacity of the battery. This is normally calculated as a percentage for the ratio of the capacity that can be discharged to the total capacity of the battery. The higher the percentage, the better.
- Round-trip efficiency: This represents the amount of energy one can get out of the battery as compared to the amount of energy that was fed into the battery. For instance, if you charge the battery with 8KWH and you are only able to get 7.5KWH, then its efficiency is 7.5/8=93.75%. While buying, aim at getting one with the highest efficiency if you can afford.
- Charge cycles: A charge cycle refers to a complete full charge and discharge of the battery (fully charging the battery and draining it to 0%). This means a battery with more charge cycles can be used longer than one with fewer charge cycles assuming they all have the same capacity. So, aim at getting a battery with as many charge cycles as possible as long as you can afford.
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