Solar Charge Controllers and Regulators

What is the function of a Solar Charge Regulator?

The main function of a controller or regulator is to fully charge a battery without permitting overcharge and at the same time preventing reverse current flow at night. Simple controllers contain a transistor that shunts 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. More sophisticated controllers 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 do solar regulators work?

The electronic circuitry in a controller monitors the voltage of the connected battery and determines the state of charge of

 the battery.  As the battery nears full charge the amount of current flowing to the battery is reduced until the battery reaches

its full state of charge.

Advanced functions.

Some solar controllers have advanced functions, these may include low battery disconnect, timers and output control.

More expensive controllers have the ability to measure amps and battery state of charge to give the user more control over

power usage and battery management.

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