Energy Storage Systems (ESS) Solar Cells 

The disadvantage of renewable energy systems is the fluctuation of the quantities of energy produced from them throughout the day and the inability to control the quantities of energy produced from them or the times of their production in a way that is consistent with the required loads. For example, in solar energy systems, energy is produced during the day only, in the hours of sunshine, and in the quantities provided by the sun’s brightness and temperatures in the installation location. As for the electrical loads, they are throughout the entire day, although there are peak hours in which the loads increase to the maximum value.

The best use of renewable energy systems is that production is compatible with loads, and this is impossible in most cases. Therefore, we resort to storing the electrical energy produced from these sources in excess of the loads’ needs at times of low demand for electricity in various ways to benefit from it in times when these sources are not available or at peak times and to mitigate the fluctuation of production. Electric energy is stored in various ways, including electric batteries, hydraulic systems, mechanical flywheel systems, ultra-high-capacity capacitors, and electric vehicle systems.

electric batteries:

Batteries:

The solar systems connected to the electricity grid do not need batteries, since the electricity grid represents for us the permanent store of electricity in cases of absence of the sun. As for solar systems that are not connected to the grid, they need batteries to store energy in cases where the necessary solar radiation is not available. Especially in the case of applications that should never be cut off from electricity, such as solar-powered watches. But more than that, this type of application requires batteries with a very large capacity, enough for many days of work without solar radiation. And in the independent systems, there are cases that do not require the use of batteries, including:

– In the case of using machines while there is solar radiation only. In this case, we do not need to store energy, since we use solar energy directly from the panels only, such as irrigating crops during the day, or direct fountains that operate directly from the solar panels. Or if there is another way to store energy, such as a solar water pump system. In this case, water can be stored in a water tank after pumping it while there is sufficient solar radiation. In the absence of the sun, we use the water tank instead of the pump.

The importance of batteries in solar systems is of great importance in the event of a desire to obtain a source of electricity at night or on rainy days with continuous clouds for long hours of the day. Due to the importance of this part in some of the solar systems that were previously explained, especially in the isolated or independent OFF GRID systems, the next part will be devoted to talking about batteries in terms of installation, types, and other related concepts and topics.

deep cycle batteries

A solar battery is a reservoir for electricity just like the water reservoir in a water pumping system. The storage capacity of a battery is measured in ampere-hours. There are three main types of batteries used in solar energy systems: liquid, gel and deep batteries. All of these species have one advantage, which is that they are deep-stored.

Liquid batteries require continuous renewal of water and acid approximately every six months, and if they are carefully maintained, they last longer, and these are more affordable than other types.

Gel batteries have many advantages over liquid batteries, which are closed batteries that do not need filling and do not require any maintenance.

Deep batteries are among the best batteries for solar system applications. They are sealed, hassle-free batteries that require no maintenance

Deep charge batteries are used in off-grid solar power systems as well as wind energy systems and in various industrial and marine applications. And solar energy batteries are of this type, as these batteries can carry out the charging process in a long time and with a low current, as well as they can discharge the charge in a long time. Also, the efficiency of charging and discharging it may reach 90% or even 95%, and this is a very large number that makes it special.

Solar energy batteries are distinguished by the size and thickness of the lead sheets inside them that are large in order to bear the load placed on them during a full charge or a complete discharge. This is what raises its price, given that lead has a high price.

Types of batteries used in solar systems and industry:

There are two main types of batteries used in solar energy systems and industry in general:

FLA – Flooded Lead Acid batteries

As is evident from its name, its lead plates are completely immersed in an electrically ionizable liquid. And you have to take into account that this type, during its work, releases explosive hydrogen gas, so you must be very careful not to have any kind of flame or spark next to it while it is working.

– VRLA Valve Regulated Lead Acid batteries

They almost do not need maintenance, and they release a negligible amount of hydrogen gas, which makes them easier to transport and install, and dealing with them is not considered dangerous.
This type has three main types 

They are   Wet  , AGM  , and Gel.

The AGM stands for Absorbed Glass Mat, which means Electro-ionizable Liquid Absorbed into a Sponge Mat.

As for the gel, it is clear from its name that the liquid has been transformed into something similar to jelly, meaning that it has become less fluid and more cohesive.

Installing the batteries

1- The cover or the outer body: It is made of compressed rubber or plastic, and it is divided from the inside into chambers to contain the plates, and these chambers are called cells. The voltage of each cell is usually about 2 volts.

2- The top cover: It is made of the same material as the outer cover, and works to protect the internal parts of the battery from external factors, and there are holes in the cover with the number of battery cells in order to fill the battery with an acidic water solution through it.

3- Sheets: – They are panels in the form of a grid containing voids that are filled with lead monoxide or lead element, depending on the type of sheets, and the sheets are divided into two main types.

A) Positive plates: The voids of the positive plates are filled with lead monoxide and are distinguished by their dark brown color.

b) Negative plates: – The voids of the negative plates are filled with lead, marked with gray colour, and the number of negative plates exceeds the positive plates by one plate.

It should be noted that each cell of the battery contains a set of positive and negative plates separated by insulating plates, and as we said, the voltage of each cell is 2 volts, and to obtain a 12-volt battery, 6 cells are connected in series.