Charge Controller

Why you need a charge controller

The main function of a charge controller or regulator is to fully charge a battery without permitting overcharge while preventing reverse current flow at night. If a non-self-regulating solar array is connected to lead acid batteries with no overcharge protection, battery life will be compromised. A simple charge controller contains a transistor that shunt the PV charging circuit, terminating the charge at a pre-set high voltage and, once a pre-set reconnect is reached, opens the shunt, allowing charging to resume.A more sophisticated charge controller utilize pulse width modulation (PWM) or maximum power point tracking (MPPT) to assure the battery is being fully charged.The first 70% to 80%
of battery capacity is easily replaced, but the last 20% to 30% requires more attention and therefore more complexity.

How to size a charge controller

Charge controllers are rated and sized by the array current and system voltage.
Most common are 12, 24, and 48-volt controllers. Amperage ratings run from 1 amp to 60 amps, voltages from 6-60 volts. For example, if one module in your 12-volt system produces 7.45 amps and two modules are utilized, your system will produce 14.9 amps of current at 12 volts. Because of light reflection and the edge of cloud effect, sporadically increased current levels are not uncommon. For this reason we increase the controller amperage by a minimum of 25% bringing our minimum controller amperage to 18.6. Looking through the products we find a 20-amp charge controller, as close a match as possible. There is no problem going with a 30-amp or larger charge controller, other than the additional cost. If you think the system may increase in size, additional amperage capacity at this time should be considered

You can browse through several models of charge controller below

Charge Controller