900-0209-01-00 Rev A
65
Applications
Array Design
Sizing Guidelines
Below is a list of maximum array wattages for the FLEXmax 100 for various nominal voltage batteries.
This should be used for sizing an array. Note that every PV module is different. The specifications for
every model should be consulted before designing or assembling a PV array.
Table 13
Maximum Input Wattage Per Charge Controller
Nominal Battery Voltage
Maximum Array Size (Standard Test Conditions)
24 V
3000 W
36 V
4500 W
48 V
6000 W
Maximum-Power Voltage (V
mp
)
Maximum-power voltage (V
mp
) is the operating voltage for the PV array at which the array generates the
most wattage. To perform battery charging, the V
mp
must always be higher than the battery voltage.
When designing the PV array, use the following rule: For optimum charging performance, the V
mp
should
be at least 6 to 10 volts higher than the highest charging voltage for that battery model.
IMPORTANT:
Check the PV array voltage before connecting it to the FLEXmax 100.
Open Circuit Voltage (V
oc
)
Open-circuit voltage (V
oc
) is the
unloaded
voltage generated by the PV array. The FLEXmax 100
controller can withstand V
oc
of up to 300 Vdc. However, if the V
oc
exceeds the following voltages, the
controller will suspend operation to protect the system components. (See pages 38 and 57.)
24-volt
system
≥
275 V
oc
36-volt
system
≥
283 V
oc
48-volt
system
≥
290 V
oc
CAUTION: Equipment Damage
Although the FLEXmax 100 shuts down at high DC voltages, this will not prevent the array
from generating voltage. Anything higher than 300 Vdc will damage the controller, whether it
has shut down or not. The array should be designed so that voltage never exceeds the
voltages listed here in order to prevent equipment damage.
