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Batteries for solar panels: Operation, types and price

he batteries for solar panels are the element that allows the energy generated by the solar panels to be stored during daylight hours. Thanks to them, energy independence from the network is achieved since they allow us to use our energy even when it is not possible to produce it, such as on cloudy days or at night. It is the best way to make the most of the solar energy captured. 

Batteries for solar panels

Batteries for solar panels offer various benefits, such as having the energy that has been generated when we need it (at night or cloudy days), that they emit almost no pollution to the environment, and a long useful life , which can exceed 15 years and where below 80% it continues to function and guarantee energy storage.  

The decision to incorporate batteries in an installation will increase its price by a percentage that will be higher the larger the project, but will allow savings in the increasingly higher electricity bill , so the terms of amortization are shortened. 

Discover the operation, the types of batteries and their cost in the following lines.  

How does a battery for solar panels work? 

Batteries allow you to get the most out of a solar installation as they offer the possibility of storing the energy that is generated and is not used at that very moment, for later consumption. These are energy accumulators that allow you to have a source of electricity for times when there is no light.  

A solar battery is made up of one or more electrochemical cells through which stored chemical energy is converted into electricity . These cells have a positive and a negative electrode . Inside the battery, the electrolytes allow the movement of the ions between the two electrodes in order to facilitate the exit of energy out of the battery. Some battery models require specific maintenance that is necessary to extend their useful life and proper functioning. 

The ability to store energy and generate electrical current is determined by the rate of charge/discharge of the accumulator and the depth of charge of the battery. The faster and deeper the battery is charged, the shorter the useful life of an accumulator will be in theory. Manufacturers recommend that batteries be discharged no more than 50%. 

Types of batteries for solar panels 

Depending on the materials with which they were manufactured, there are different types of batteries for the storage of solar energy depending on their manufacturing technology. 

Monobloc Batteries 

The most common, recommended and economical model to use in low and medium power solar installations are open lead acid monoblock batteries . These batteries are indicated for the use of simple electrical devices without a motor (lights, microwaves, television…). These are high-performance batteries for self-consumption solar installations. Widespread in caravans, “camperized” vans and small houses or sheds for storage or tools.

This type of battery can have 3 or 6 internal cells of 2V each, connected to each other forming a single block of 6V and 12V, respectively. The cells of these monobloc batteries are made of lead and electrolyte. Regarding the capacities of these batteries, it should be noted that there are all kinds of options: from <100Ah to 800Ah. 

Other models of monobloc batteries are AGM batteries and gel batteries , in which the electrolyte is gelled, with which they achieve more performance, and can be used in more complex situations or that require more power. These batteries can be used in solar installations with motorized technological devices, such as washing machines or water jets. These monobloc batteries can withstand high starting peaks, which is what many common household appliances require.  

Depending on the need, they could be used to supply a small home without much electrical equipment. Its great advantage over open lead acid is that it lasts longer. Although the characteristics of these batteries are altered by the use made and the intensity of the discharge, the life cycles of monobloc batteries can be summarized as follows: 

  • Monobloc gel batteries > +1100 charge cycles 
  • AGM monobloc batteries > +500 charge cycles 
  • Open lead acid monoblock batteries > +350 charge cycles 

stationary batteries 

Stationary batteries are very popular for photovoltaic installations of medium and high consumption, they offer a useful life of close to 20 years, thanks to the fact that the lead plate inside is tubular and has more lead than monoblock batteries. , which has the flat plate. The main virtue of these batteries is that they offer great resistance to continuous charge-discharge cycles. 

Like monobloc batteries, there are different types of stationary batteries depending on storage capacities and durability, with open lead acid and gel batteries being the most accessible. Stationary gel batteries have less maintenance than open lead acid batteries, and both are recommended for use in homes, farms or daily use facilities , where the consumption to be carried out is previously known.  

lithium batteries 

Lithium batteries are the bet for the future and little by little their presence is becoming more common in installations as they offer high durability and require little maintenance . They are the most profitable in the long term due to their greater loading and unloading depth (close to 90% of their capacity). Its smaller dimensions also stand out among its features. The drawback, in addition to the fact that they have a higher price, is that for a high starting point, the installation of several batteries is necessary since they do not support the punctual charge of some devices well.  

Unlike conventional batteries, this type of battery offers integrated intelligent management and lasts 6,500 charge cycles.

Lithium batteries can be classified based on their voltage . In this way, we differentiate between Low Voltage (LV) and High Voltage (HV) batteries.

High Voltage (HV) batteries guarantee greater efficiency, although the choice of one type or another will depend above all on the inverter equipment we choose. If it is a hybrid inverter with a backup option, we will need an HV battery. For all other battery-compatible inverters, the best option is the LV lithium battery. HV batteries have a greater voltage range and three-phase connection. 

Price of batteries for solar panels 

We have already seen the main differences between the different types of batteries , which shows the most varied characteristics and functionalities depending on what each installation needs. In addition to the material , the capacity and the useful life , there is a factor that refers to the amortization time that must be taken into account when making calculations. A scenario of an exponential rise in the price of electricity can completely change the perception of the investment cost of an installation.  

As a guide, we can say that monobloc batteries are the cheapest , while lithium batteries can cost twice as much, in absolute terms. In an intermediate place are the stationary batteries . However , there are various grants and subsidies for the installation of batteries. To obtain state aid from European Next Generation funds, it is necessary that the batteries are lithium and that they offer a guarantee of at least 5 years, in the case of batteries offered by POWEN, their guarantee is 10 years. To find out the savings and the budget that best suits your needs, contact POWEN .  

POWEN will give you the ideal and personal advice that your installation needs . POWEN ‘s team of professionals has the necessary experience to indicate the ideal systems according to the characteristics of your home.