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Solar Charge Controllers. Alison Ray and Scott Hamshaw. Basic Functions. Prevents battery overcharge Blocks reverse current Prevent over-discharge from batteries (some models) Prevent electrical overload (some models) Displays battery status. Blocking Reverse Current.
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Solar Charge Controllers Alison Ray and Scott Hamshaw
Basic Functions • Prevents battery overcharge • Blocks reverse current • Prevent over-discharge from batteries (some models) • Prevent electrical overload (some models) • Displays battery status
Blocking Reverse Current • To prevent night discharging of batteries, controllers pass current through a semi-conductor only allowing current to flow in one direction. • Some controllers use a relay to switch off at night • Very small systems can use a simple diode to prevent discharge.
One and Two Stage Charge Controllers • Most basic form of charge controller • Work by simply switching current fully on/off (1 stage) or reducing current in two steps (2 stage) • Utilize relays to act as a simple disconnect
Pulse-Width Modulation (PWM) Controllers • Battery is charged using pulses of energy that can vary in length and speed according to battery condition. • As the battery reaches capacity, the flow of energy is slowly tapered off as opposed to sudden cut off to reduce battery overcharging • Ideal for situations where excess energy is often present • higher charging efficiency • rapid recharging • healthy battery at full capacity
Maximum Power Point Tracking Controllers • A MPPT controller adjusts the voltage output to take advantage of the Vpp and charge the battery more • Peak Power Voltage (Vpp) is the maximum power point that a PV system can deliver; varies with temperature and sunlight intensity • Vpp is higher in colder and sunnier conditions therefore, MPPT controllers are ideal for cold climate use where battery use is high
Prices for Typical Charge Controllers For a list of Charge Controller Manufacturers visit http://www.solarbuzz.com/solarindex/RegulatorManufacturers.htm