In hybrid solar power systems however, that is, systems that incorporates both solar panels and a battery bank, batteries store electricity generated from the panels during the day for use by appliances in the absence of production from the solar panels.
All batteries have essentially the same components: electrolytes, positive and negative terminals and separators integrated into 'cells'. These components are often differentiated based on the nature and/or type of the chemical material from which they are made.
In both AGM and Gel batteries, the electrolyte of a lead-acid battery is treated to eliminate constant checks and maintenance and to remove the safety risks that come with the emission of gases and acid fumes from the traditional battery technology in which the acid electrolyte is held in the battery in liquid form. The new adaptations also made transportation and installation safer.
In a Gel cell battery, the acid electrolyte is made into gel-like liquid by adding silica dust to the electrolyte, forming a thick putty-like gel. Gel is usually produced by homogeneously dispersing fumed silica in diluted sulfuric acid. The Gel battery has no liquid inside, the electrolytes is in gel form and stand solid between positive and negative plate inside battery.
In an AGM (Absorbed Glass Mat) battery, the acid electrolyte in the gel form is held in glass mats, as opposed to freely flooding the plates with a glass fibre separator between the plates. The need for performing a standard maintenance, that is, topping distilled water to maintain the acid level is eliminated when the oxygen produced at the positive plates combines with hydrogen produced at the negative plate to give water.
AGM and GEL batteries have similar characteristics and are often mistaken as the same by amateurs. But there are key differences. In comparison, AGM are better because:
They have a lower internal resistance and are thus preferable when a burst of current is required for a short time and are good as starters. They are thus widely found in the automobile and RV applications. On the other hand, GEL batteries are not suitable as starter batteries because their gel form gives them an increased acid resistance.
The pores of the Gel structure are narrow meaning that the ions are more clogged. Therefore, AGM's electrical performance is better than that of Gel batteries.
They can be charged faster, in some cases, up to 5X faster than GEL batteries.
They are produced at a cheaper cost than Gel batteries and are thus cheaper. AGM batteries sell better and are more widely used than Gel batteries.
They perform well at temperatures below freezing point.
Gel batteries are more sensitive to charging and require special chargers while AGM batteries can be charged in conventional ways. Battery chargers with Gel profile will have information about Gel compatibility.
Gel batteries have higher ventilation requirements. They must be well ventilated. AGM has 8% of the gap in the separator, and no electrolyte is filled.
The GEL electrolyte is 20% denser than AGM, giving AGM batteries a higher energy.
On the other hand, Gel batteries are considered better options than AGM batteries because
They are built to operate at higher temperatures. The negative impact of high temperatures on high rate discharges is small as compared with AGM batteries.
Also, they can be discharged up to 90% and still get a much better cycle life in comparison with to AGM batteries.
Gel batteries are very resistant to vibrations and are more popular in the shipping industry.
Gel batteries with positive tubular plates achieve a proven service life in storage applications of more than 15 years.
They come with a battery cycle life that is almost twice than of an AGM battery cycle life.
Also, due to their slow discharge rate which in turn is due to limitation of plate distance and the resistance of the cell, they are excellent for use in emergency applications. This makes them highly reliable for medical equipment and use in hospitals.
An already large and still increasing range of available options can lead to information anxiety and confusion that can result in a poor decision being made. In situations like this, Solarkobo has university-trained engineers who have acquired years of field experience to help users make the best choice of batteries that fit their budgets and meets their power needs. Since majority of our installations are for homeowners and businesses, we recommend AGM batteries over Gel Cell batteries. They are cheaper and are more widely available in markets.