One of the most important component parts of any solar system is the solar battery which effectively is used as backup or the unit to store solar energy for use at a later time. Solar batteries work in a similar way to ordinary domestic batteries.
How Batteries Work
Batteries generally have three component parts, an anode, a cathode and the electrolyte. The battery has chemical reactions within it which cause the buildup of electrons at the anode. When this happens it also creates an electrical difference between the cathode and the anode.
The electrolyte is there to keep the electrons from going straight from anode to cathode in the battery. When this circuit is closed, perhaps by connecting the anode and cathode by a wire, then the electrons will get access to the cathode.
But the electrochemical processes change the chemicals within the battery so that they stop supplying electrons, thus there is only a certain amount of power in one battery.
But in a solar battery there is a capacity to recharge it, this is done by changing the direction of the flow of electrons using another power source such as a solar panel.
Types of Batteries Used Today
There are three main types of batteries that are in use today:
Lead Acid – Deep Cycle, VRLA, AGM, Gel
NiCad – Nickel-cadmium battery vented cell type
Lithium-ion – Polymer
New Technologies Emerging
The world of the battery is ever changing and there are new developments and technologies happening all the time. For instance there are now improved Lithium-ion, salt and even solid-state lithium-ion batteries that are currently being tested for the market.
As for Kunini, we are moving towards the Lithium type battery technology for Solar Storage. We have seen that the normal VRLA or Solar Gel batteries are not suitable for the temperatures in Thailand, and do not last very long.
Initial costs for Lithium batteries are higher but the ROI is far better because they last much longer. These types of batteries also give much better Depth of Discharge (DOD).
Kunini advise clients that if they opt for a VRLA or Solar Gel battery source they will need to be swapped over in three to four years. But a well maintained Lithium battery can last a decade.
The price differential between the two types of batteries is not that large, so here at Kunini we advise opting for Lithium batteries from the start. If your thinking is to start with VRLA/Gel batteries and swap them later for Lithium then you need to make certain that the solar inverter is able to accept both kinds of technology.