Panels photovoltaic solar energy

Installation of thermal solar energy

Solar power plant
Thermoelectric

Solar batteries

Solar batteries

The batteries in a photovoltaic solar energy system is to accumulate the energy produced by the photovoltaic panels during the hours of Sun to be able to use it at night or on cloudy days.

The use of batteries also allows to provide a higher current intensity than a functioning photovoltaic panel can offer. This would be the case if several electrical appliances were used at the same time.

A battery consists of small 2V accumulators integrated in the same element; Has direct current at 6, 12, 24 or 48V. The accumulator is the cell that stores energy through an electrochemical process. Thus, when we talk about a 12V battery, we are talking about a series set of 6 lead-acid cells of 2V each.

Battery operation

The batteries have the function of providing electrical energy in the system at the moment when the photovoltaic panels do not generate the necessary electricity (for example at night or in low light).

At the time that photovoltaic panels can generate more electricity than the demanded by the electrical system all the energy demanded is supplied by the panels and the surplus is used to charge the batteries.

Solar battery type

There are two types of batteries according to your cycle:

  • Low Cycle Batteries
  • Deep cycle batteries

Low Cycle Batteries

Low-cycle batteries are designed to supply a quantity of current for a short period of time and withstand small overloads without losing electrolytes, as in the case of cars.

However, these batteries do not withstand deep discharges. If they are discharged repeatedly below 20%, their service life is shortened considerably. Therefore these batteries are not a good choice for photovoltaic solar systems.

Deep Cycle Batteries

They are designed to be discharged repeatedly up to 80% capacity. This feature makes them the best choice for solar power systems.

Characteristics of an accumulator

One of the most important when choosing an accumulator is the capacity, which is the amount of electricity in amps (A) that can be obtained from a complete discharge of the accumulator when it has a state of full charge.

Another important parameter is the load efficiency, which is the ratio between the energy used to fill the accumulator and the one actually stored. Therefore the closer to 100% the better.

Self-discharge, process of an accumulator that is not in use tends to discharge.

Depth of discharge, amount of energy that is obtained during a discharge while under full load (%).

Factors to consider

The useful life of a battery for solar installations is usually about 10 years, but if frequent discharges are carried out in depth (> 50%) its useful life falls sharply. Therefore, it is convenient to install enough capacity so that 50% of the discharge is not exceeded.

Another very important factor is the temperature, if the temperature is maintained between 20 and 25ºC, the useful life will be around 10 years, but if it is altered in 10ºC, the useful life can reduce to half.

The useful life of a battery for solar installations is usually about 10 years, but if frequent discharges are carried out in depth (> 50%) its useful life falls sharply. Therefore, it is convenient to install enough capacity so that 50% of the discharge is not exceeded.

Another very important factor is the temperature, if the temperature is maintained between 20 and 25ºC, the useful life will be around 10 years, but if it is altered in 10ºC, the useful life can reduce to half.

Battery Types

Batteries are classified according to the type of manufacturing technology as well as the electrolytes used.

The most commonly used batteries in solar installations are lead-acid, for the price ratio for available energy. Its efficiency is between 85-95%, while Ni-Cad by 65%.

Surely the best batteries would be lithium (mobile) but not economically viable.

Acid-lead batteries for solar applications

All lead-acid batteries fail prematurely when they are not fully recharged after each cycle. If a lead-acid battery is left unloaded (for days) at some point, this will result in permanent loss of capacity.

Liquid Batteries - Liquid Electrolyte

They are the most used. There are two types of liquid batteries: open, with lids that allow the water to change. Sealed, they are closed but with valves that allow the outputs of the possible gases during excessive loads.

Advantages of liquid batteries:

  • Oldest
  • Their production allows for economical prices.
  • They are less problematic to overloads.

Disadvantages:

  • There is danger of losing fluid (aggressive).
  • They usually have a short shelf life, between 400 loading and unloading cycles.
  • Very low temperatures can quickly destroy them.

There are other types of batteries, where the electrolyte is not in the liquid state, it has been immobilized. In the case of gel batteries, the electrolyte has been geladificat, and in the case of AGM (Absorption Glass Mat) has been separated by a glass fiber, with great absorption power, which acts as a sponge. Both gel batteries and AGMs are maintenance free, you will never need to add water.

Batteries AGM - Absortion Glass Mat

They are the most modern batteries and the acid is fixed in glass fibers that absorbs it.

Almost all AGM batteries are valve regulated, VRLA (valve regulated lead acid)

They have all the advantages of ice, in addition to the following:

Advantage:

  • Good shelf life.
  • More resistance to cold climates.
  • Your auto download is minimal.
  • Low internal resistance allowing high currents.
  • Deep cycle.

Disadvantages:

  • Price higher.

Increasingly AGM: lead-acid batteries are increasingly being used, because of their lifetime / price ratio, as well as their easy handling.

For someone who can ensure the necessary care, the liquid battery may be the best option, especially considering the price.

Batteries AGM - Absortion Glass Mat

They are the most modern batteries and the acid is fixed in glass fibers that absorbs it. Almost all AGM batteries are valve regulated, VRLA (valve regulated lead acid) They have all the advantages of the ice, in addition to the following:

Advantage:

  • Good shelf life.
  • More resistance to cold climates.
  • Your auto download is minimal.
  • Low internal resistance allowing high currents.
  • Deep cycle.

Disadvantages:

  • Price higher.

Increasingly AGM: lead-acid batteries are increasingly being used, because of their life / price ratio, as well as their easy handling. For someone who can ensure the necessary care, the liquid battery may be the best option, especially considering the price.

valoración: 2.9 - votos 7

Last review: June 8, 2017

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