- Outback Power Systems, Inc. Battery Charger User Manual
10
PB
2. Determining Wire Sizes
Open Circuit Voltage/Wire and Disconnect Size
Maximum Open Circuit Voltage (VOC)
• VOC is the
unloaded voltage generated by the solar array.
• Greater than 145VDC
g FLEXmax 80 suspends operation to protect components
• 150DC
g max open circuit voltage with the coldest environment
NOTE: Although the FLEXmax 80 shuts down at a voltage greater than 145VDC, it can withstand up to
150VDC from the array; anything higher than 150VDC will damage the FLEXmax 80).
• As every brand of panel is dierent, be sure to know the manufacturer’s specications.
• Weather conditions vary and will aect panel voltage.
• Hot weather: lower open circuit voltage/lower maximum power point voltage
• Cold weather: higher open circuit voltage/higher maximum power point voltage
• Allow for ambient temperature correction using the following table:
25° to 10° C (77° to 50° F) multiply VOC by 1.06
9° to 0° C (49° to 32° F) multiply VOC by 1.10
-1° to -10° C (31° to 14° F) multiply VOC by 1.13
-11° to -20° C (13° to -4° F) multiply VOC by 1.17
-21° to -40° C (-5° to -40° F) multiply VOC by 1.25
• Check the PV array voltage before connecting it to the FLEXmax 80 (see page 76)
Wire and Disconnect Sizing
• The output current limit of the FLEXmax 80 is 80 amps.
• Use a minimum of 4 AWG (21.15 mm
2)
wire for the output between the FLEXmax 80 and the battery
bus bar conductors.
• Install OutBack OBB-80-150VDC-PNL breakers for disconnect and overcurrent protection.
• The largest PV array that can connect to an FLEXmax 80 must have a rated short-circuit current of 64
amps or less under STC (Standard Test Conditions).
• Input conductors and circuit breakers must be rated at 1.56 times the short-circuit current of the PV
array. OutBack 100% duty continuous breakers only need to be rated at 1.25 times the short-circuit
current.
• Please see the wire Distance Chart and complete Wire and Disconnect Sizing on pages 77-79 for
other suitable conductor/wire sizing.