Solar Battery Technology

There are various types of batteries that can be used to store the energy from a solar system, including; Lead acid, AGM + Gel Batteries, AGM batteries, Lead Crystal batteries, Flow batteries or lithium Ion batteries.


1) Lead acid

Deep-cycle, lead-acid batteries have been utilised in Solar energy systems globally for decades. Due to existing and improved manufacturing technologies over the years deep-cycle, lead-acid batteries cost less than lithium-ion or Flow batteries.

Valve-regulated lead-acid (VRLA) batteries encompass AGM (absorbed glass mat) and gel models. AGM batteries were mainly manufactured for standby purposes such as emergency backup, but not deep cycling. Newly available deep-cycle AGM battery designs provide better performance and output which makes them a superior choice for solar applications at a better price point than gel batteries.

Many different elements such as design and continued maintenance influence the life of a battery, which makes it a challenge to predict the life cycle of a battery. Lead-acid batteries require diligent, regular maintenance and battery enclosures should be well ventilated to reduce hydrogen gas accumulation. AGM and gel technology batteries are maintenance free and as there is no acid in them, they can be installed in any position except upside down. Solar applications are often in isolated areas so using maintenance free batteries often negates the extra initial cost.

The correct disposal of lead-acid batteries is extremely important and should be handled professionally so they can be recycled in the correct way.


2) Lithium-ion

Power tools, smartphones and Hybrid & Electric motor vehicle among many other devices all use Lithium-ion batteries making them the most popular form of energy storage regardless of the application. Prismatic or pouch cell (soft pack) designs can be utilised for solar energy storage, specifically lithium iron phosphate (LFP) batteries. The soft pack design increases efficiency, reduces weight and cost.

Lithium-ion batteries are more expensive that lead acid batteries although as the number of applications for their use increases, prices are steadily dropping. Until such time the pricing is in line with Lead acid batteries, the best way to lower the ROI is to ensure that the sizing requirements are correctly calculated which can in turn reduce the cost of secondary devices such as charge controllers negating the higher outlay price.

Lithium-ion batteries provide more charge than lead-acid over the battery lifecycle. The most important benefit that lithium-ion batteries provide solar systems is high charge and discharge proficiencies, which assist in harvesting more energy. When inactive Lithium-ion batteries lose less of their capacity, which is beneficial in solar installations where energy is used infrequently.

As Lithium-ion batteries are typically lighter and more self-contained than lead-acid batteries, they can be place indoors or outdoors, require far less space and can be wall mounted, which can make a big difference where space is at a premium. They are also maintenance free.

Recycling of Lithium-ion batteries is not straight forward and depends whether the technology uses organic or inorganic cells. Batteries with organic cells are not toxic so can be easily recycled. Due to recycling process of batteries with non-organic cells is often not commercially viable than obtaining brand new material for manufacture

 

Flow batteries

Flow batteries sometimes referred to as a redox flow battery, are emerging as an alternative to other batteries. The battery uses a chemical reaction (two chemical elements dissolved in liquids) to produce energy.

Vanadium (a chemical element) sourcing more cost effectively, from sources such as “flyash” (a derivative produced by coal-fired power plants) and increasing power density is the key to reducing pricing in the future.

The complex chemistry nature of these batteries, necessitate equipment such as control units and peripheral containment vessels, requiring significant space for installation compared to other battery technologies.

Flow batteries have a much longer life-cycle than other technologies as the vanadium electrolyte doesn’t degrade over time. Another benefit of this technology is; to increase battery size all that is required is to add more electrolytes. Batteries can be charged and discharged an unlimited amount without affecting battery life.

The vanadium in the batteries is non-toxic and is easily recycled.

 

Lead Crystal batteries

Overcoming the deficiencies such as a short lifecycle, the water loss rate, poor low temperature performance is why Betta Batteries developed Lead Crystal® batteries. 

Lead Crystal batteries can be cycled far more and discharged deeper than traditional lead acid batteries. They are safer than lead acid batteries, they contain an electrolyte solution that when charged and discharged solidifies into a white crystalline powder.  

Lead crystal batteries are 99% recyclable. One major disadvantage is they are only manufactured by Betta batteries in the USA.

 

Lead Crystal batteries

Overcoming the deficiencies such as a short lifecycle, the water loss rate, poor low temperature performance is why Betta Batteries developed Lead Crystal® batteries.  

Lead Crystal batteries can be cycled far more and discharged deeper than traditional lead acid batteries. They are safer than lead acid batteries, they contain an electrolyte solution that when charged and discharged solidifies into a white crystalline powder.  

Lead crystal batteries are 99% recyclable. One major disadvantage is they are only manufactured by Betta batteries in the USA.


How do I select a battery? Should this section and the one below not be first before Technologies?

The key to selecting the correct battery type and size of battery is determining what you intend to use the battery back-up for:

  1. As back-up for electricity outages,
  2. In an off-grid system where storage is required and
  3. For use during the evenings, where charging takes place during daylight hours.


What affects the battery life?

The “depth of discharge” (how much energy you use from your battery before you charge it up again) affects battery life.  The lower the depth of discharge (D.O.D) the longer the battery will last, for example; if only 20% of the capacity at full charge is utilised, the battery life will be significantly longer than a battery that continuously uses 40% of its capacity, this is another reason that has to be considered when calculating battery capacity for a system or the battery type. Battery life is also affected by continuously high and low temperatures in the space they are stored.