Solar energy storage, as the name suggests, is the act of storing energy from the sun for later use. Although there are various systems, generally for private and business use, the storage will be done with the help of solar batteries. These batteries are responsible for storing energy during the day to use at night or during periods when solar radiation is not sufficient.
The batteries are therefore the solar storage system par excellence. By using it energy independence is obtained through the ability to accumulate electrical energy and thus allows to take full advantage of solar energy.
A great benefit offered by batteries from self-consumption installations in homesis the possibility of disconnection from the electrical network to obtain energy independence. Another case in which they are very useful is that of properties located in areas where it is very complex to connect to the electrical network. In addition, they produce almost no pollution, have a long service life of up to 15 years and allow increases the energy consumed from the solar panels and reduces the electricity bill.
Function of a solar battery
As mentioned, the photovoltaic battery allows you to store the energy that is generated thanks to the solar panels during the hours of sunshine, so that you can use it when the production of energy is not possible, such as on cloudy days or at night. So, we will have electricity at any timeeven when the solar panels are not working because they generate surplus energy from solar radiation.
A the solar battery is composed of one or more electrochemical cells by which chemical energy is converted into electricity. Cells have a positive and a negative electrode, as well as electrolytes that allow ions to move between the two electrodes to facilitate the flow of current in the battery.
This process can be summarized in the following steps:
- The photovoltaic solar panel receives radiation from the sun during the day and converts it into electricity that powers the installation.
- Excess energy is stored in the battery or batteries that the installation has to be able to use them at night or on days with unfavorable weather conditions.
Types of batteries for solar panels
They are called batteries that work as a solar energy storage system deep cycle batteries. They are called so because they are charged and discharged frequently and their duration is very long compared to conventional batteries.
The different types of solar cells that exist today are:
Monobloc or monobloc batteries
They are used for self-consumption installations of low and medium power (lighting and low power appliances). Their life is shorter in terms of deep discharge cycles and if the manufacturer\’s instructions are followed, they can have a useful life ranging from 4 to 10 years. They are the cheapest and therefore perfect to start self-consumption.
Monobloc batteries usually have voltages between 6v and 12v. For example, if the installation we are going to make is 48V, we would need 4 12v monobloc batteries or 8 6v monobloc batteries.
Among the monobloc battery models, the gel batteries and AGM batteries in medium power installations. They offer excellent performance and are maintenance-free. Charge-discharge supports the large starts of household appliances, but they are not as powerful as stationary batteries.
stationary batteries
Its use is indicated in medium or large consumption solar installations, such as household appliances with higher power (oven, washing machine…), machinery, etc. They last longer than monobloc batteries as well in terms of deep discharge cycles. Its useful life reaches about 20 years, so its cost is also higher.
This type of battery consists only of 2v cells, so that if the solar installation is 48v, it will be necessary to use 24 2v cells.
lithium batteries
They are currently the most sought after due to their low maintenance and high durability, which is why they are one of the best options or even the most efficient on the market. They can be used at a greater depth of discharge and have a greater number of discharge cycles.
It can even be said that lithium batteries are the future of efficient batteries in the home.
the cost of solar batteries
Before opting for a certain battery for our self-consumption photovoltaic installation, it is necessary consider the power consumption we are about to make in the home and the size of our photovoltaic installation. It is very important to oversize the system by 160% relative to the charging power of the battery to be able to charge and self-consume at the same time. A 2.5kW battery usually has a market price of €1,500 or €2,000, and one with higher power can reach 5,000 euros. As a consequence of this, having a battery in an average self-consumption residential PV installation increases its cost by 30%. If it is a large photovoltaic installation, having a battery increases the price of the installation by almost 70%.
