Solar Charge Controllers Explained

Solar Charge controllers or voltage regulators protect the batteries from overcharging, subsequent gassing, loss of electrolyte and possible plate damage. Power from the solar panels is high voltage and can be damaging to batteries if not regulated.

By monitoring battery voltage solar charge controllers regulate the charging current from the solar arrays enabling the batteries to be charged properly and safely but not over-charged. They also contain a suitable protection to prevent any current drain from the battery to solar array eg. at night. This is usually best done by gradually reducing the flow of energy into the battery as a full charge is reached so achieving a more complete charge.

A switching technology known as Pulse Width Modulated (PWM) control or Maximum Point Power Tracking (MPPT) is used to control and monitor battery charge. Some solar charge controllers also include a low voltage warning or disconnect function to switch off loads if the batteries become very low preventing excessive discharge. Discharging batteries to very low levels can be very damaging and can potentially cut the battery cycle life. The Charge controllers can also have optional displays that indicate charging currents, load currents and battery voltage, or separate meters and system monitoring can be used.

In choosing the proper solar charge controller the main consideration is the peak charging current you need to regulate. It is worthwhile selecting one that will handle extra power if needs change in the future. So, there is a need to consider oversizing to cater for any future energy expansion. Controllers should not be used with more modules than they are rated for. However, solar panels can be split into sub-arrays each with its own charge controller, in order to accommodate increasing numbers of modules. For the smaller output panels, or where a relatively large battery store is used, regulators may not be necessary.

At Fotis energy we carry both the PWM and the MPPT from 10A to 60A. Please get in touch with one of our Reps who will recommend you the best one for your needs.