Download Charge Controllers

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
Brand/Model
Type
Amperage
Price
Xantrex C40
PWM
40
$159.
Blue Sky Energy
Solar Boost 3024i
MPPT
30
$299
Morningstar
SHS
PWM
10
$40
For a list of Charge Controller Manufacturers visit
http://www.solarbuzz.com/solarindex/RegulatorManufacturers.htm