Choosing a battery for our solar energy system is essential if we want it to work properly, as well as to avoid unnecessary expenses or that it deteriorates rapidly due to being used in an improper installation. The choice of batteries varies depending on the facility we haveas well as from the number of solar panels and other aspects.
Types of batteries for solar installations
Lead acid batteries are not the same as lithium batteries, just as Monoblock batteries and AGM batteries or stationary batteries are not the same. In this article we explain everything you need to know about each of these batteries so that you can make the right purchase, as well as some aspects of interest that you need to know, first of all. We explain it to you below!
What are solar batteries?
Solar batteries are responsible for storing the electrical energy generated through solar panels. These batteries are used in isolated photovoltaic solar installations, that is to say, those that do not pour the current into the network since they use the energy generated throughout the day to make use of it in the hours of little or no sunlight. In general, batteries are made up of two electrodes that are immersed in an electrolyte where the charge and discharge reactions take place. the way you are must always be connected in series, avoiding parallel connections as this can generate an overload.
You must also be clear that the unit of measurement for batteries —whether they are lead acid batteries, lithium batteries, stationary batteries or any other— is measured in amps/hour. The capacity of a battery can be defined as the amount of energy that is obtained from a battery during a complete discharge.
What are the most used solar batteries?
In general, the most used solar batteries are those that are made with liquid electrolytealthough we can also find other types of batteries that instead of having the ions flowing freely, these are immobilized —they are known as dry batteries, like AGM batteries—.
Lithium battery vs lead acid
One of the most frequent doubts when buying a solar battery is whether we should buy a lithium battery or a lead acid battery. The truth is that lead acid batteries are the most used because they are cheaper, however, lithium batteries have come a long way and are getting closer to establishing themselves as an alternative. These provide a large number of advantages, among which are: a higher energy densityhave much longer lifespan, low self-discharge rate, faster chargeability, no overheating, no maintenance and safer.
Types of batteries for solar installations
Having clarified this information of interest on the use of batteries, we will now explain what the main types of batteries are to clear up all doubts and so that you know which one goes best with your electrical installation.
Monoblock batteries are those that are intended for small facilities such as lighting, television, refrigerator or computer. These are simple installations that do not have motors. It is the cheapest battery that we can find on the market and the simplest in terms of its composition. This is made with lead acid, which involves an evaporation of gases after heating. This implies an annual maintenance to measure the electrolyte. Monobloc batteries should not be installed in closed places.
They are batteries recommended for installations with very high currents in short periods of time, since its resistance is very low. This type of batteries belongs to the type of immobilized electrolyte batteries. They have gas regulation valves through which losses are avoided. It is therefore about maintenance-free batteries, unlike the Monoblock.
What happens with these AGM batteries is that the lead acid is absorbed between the plates and immobilized by mats made of fiberglass. Regarding its use, this type of battery is designed for small isolated installations. They can be used in places with vibration, such as caravans, and exposed to low temperatures —up to -4 ºC—. In general, its use is recommended in spaces where a fully sealed battery is needed for safety reasons. AGM batteries are very safe.
They are batteries that take up very little space and do not emit any type of gas, which is why they can be installed anywhere. These types of batteries are usually more expensive. than the rest, the reason for this has to do with all the advantages they offer. And it is that this type of battery charges much faster and total discharges do not affect its life cycle. These lithium batteries stand as an alternative to lead acid batteries.
The stationary battery, or stationary gel battery, does not require any maintenance, so there is no need to worry about internal acid levels. These are batteries that have a long useful life and are ideal for installations in which a daily consumption over long periods of time. These batteries are made up of 6 vessels of 2v each, so they are capable of storing a high electrical charge.
Deep cycle or gel batteries
These types of batteries are designed, above all, for solar installations with average consumption and use throughout the year. These are batteries very similar to Monoblock batteries, although these have a higher size and are intended for daily use facilities. Although their price is slightly higher, these offer a durability 3 or 4 times higher than the Monoblock. This translates into a useful life that ranges from 6 to 7 years, approximately. It adequately supports full downloads without its useful life being reduced.