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OPzS and OPzV Batteries

Updated: Jul 7, 2020

In an inverter system, batteries play very important roles. First, they provide the needed DC that will be converted to DC for use in appliances. And second, in off-grid situations, they help store excess electricity generated from solar panels for use at a subsequent time.

While all batteries have essentially the same components, electrolytes, terminals and separators integrated into 'cells', they are often differentiated based on either the nature of their most basic component, their electrolytes, or their plate technology. Based on their plate technology, inverter batteries can either be Flat Plate or Tubular.

Differences Between Tubular and Flat Plate Technologies

The definitive features of the tubular battery are the multi-tube bag gauntlet and increased surface area of the positive plate.

Due to increased positive plate surface area, tubular batteries have 20% more electrical capacity than flat plate batteries of comparable size and weight. With less positive plate shedding, tubular batteries also provide up to a 30% longer service life than flat plate batteries. Generally, tubular batteries are the preferred of the two types of batteries.

Based on the nature of their electrolytes, batteries can either be

  1. Flooded Lead Acid (FLA)

  2. Valve Regulated Lead Acid (VRLA)

A Victron Energy OPzV Battery

Flooded Lead Acid

Flooded lead acid (FLA), is the traditional battery technology. As the name implies, the liquid electrolyte in the battery is in the liquid form. FLA batteries require constant maintenance checks which may be a heck to some people. Also, the increase the risks of spillage, explosions and domestic accidents. Read how to maintain FLA batteries here.

Valve-Regulated Lead Acid

VRLA batteries are batteries constructed to eliminate the need for constant checks and to eliminate the emission of fumes or gases on a continuous basis and the attending dangers. To remove the need for constant maintenance, they are adjusted in these three ways:

  1. 1. FLA batteries have openings at top from where distilled water is to be added for maintenance and safe running. This can be sealed off and replaced with a self-regulating valve.

  2. By holding the acid electrolyte in glass mats, as opposed to freely flooding the plates. A battery constructed in this way is called Absorbent Glass Material (AGM) battery.

  3. By making the acid electrolyte into gel-like liquid. This is done by adding silica dust to the electrolyte, forming a thick putty-like gel. A battery constructed in this way is called a Gel Cell battery.

OPzS and OPzV batteries are both types of the tubular-plated battery. The differences is in the nature of their electrolytes. While the acid electrolyte of OpzS is FLA, the OPzV is VRLA. It electrolyte is made into gel by the addition of silica dust. Hence they are also referred to as "silicone batteries". Also, the OPzV is valve-regulated, sealed and thus, maintenance-free. Read more about maintenance-free batteries here.


They have a cell voltage of 2V and have to be connected in series to produce higher voltages. Also, they are differentiated from the other types of batteries by their upright and vertical orientation.

(OPzS is an abbreviation of O 'Ortsfest' (stationary), Pz 'PanZerplatte' (tubular plate), S 'Flüssig' (flooded). OPzV stands for Ortsfest (stationary) PanZerplatte (tubular plate) Verschlossen (closed).)

Victron, Outback, Sunlight, Hoppecke, NorthStar, Microtek and other solar and inverter manufacturing companies have a range of OpzS and OPzV inverter batteries. Check out our list of battery prices here.

Read about another type of batteries, Lithium-ion batteries, here.


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