What Is A Solar Charge Controller?

When you purchase a solar home installation with battery backup, one of the components you will need to select is a solar Charge Controller. What is this object and why is it necessary?

solar panels produce direct current, meaning the electricity from the panels flows in only one direction. They must do, as they cannot produce any other form of current. This current is passed to both the charge controller to top up the batteries and operate household items or to the inverter, to pump electricity into the grid if there is excess.

The quality of the charge controller will directly affect the life of the backup batteries. This is due to the particular chemistry involved in the depletion and recharging of the Lead Acid Accumulator batteries. When the battery is depleted of charge, the lead plates inside the battery are corroded. It is this corrosion that provides the electricity. When the battery is recharged, the plates are rebuilt, the opposite of the depleting reaction.

Sufficient charge delivered in the right volumes at the right time will allow the terminal plates inside the battery to be restored to as close to their previous condition as possible. This happens through growth of metal crystals on the surface of the plate. If this crystal growth does not happen at the optimum rate to generate large stable crystals, chunks of the metal will drop off the plate and build up at the base of the battery. This is the cause of the slow degeneration of car and other types of lead acid batteries.

Lead Acid Accumulator batteries are expensive and also contain a great deal of material and so have a high manufacturing energy. Selecting a good quality charge controller will maximize the life of these batteries in a solar home system. Buying a cheaper controller will result in shorter battery life and a greater long term cost as you will need to replace the batteries sooner than you should. Then, unless you want the same thing to happen, you will also need to replace the charge controller.


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