Outback FM60 User Manual
Applications
102 900-0009-01-00 Rev D
Hydroelectric and Fuel Cell Applications
Performance Optimization
The FLEXmax Charge Controller is designed to work with PV arrays. Although it will work with
hydroelectric turbines and fuel cells, OutBack Power Technologies can only offer limited
technical support for these applications due to variance in turbine and fuel cell specifications.
IMPORTANT:
The FLEXmax Charge Controller is not usable for direct regulation of wind turbine input and
OutBack cannot warranty its use in these applications. In wind turbine applications, the
FLEXmax is recommended as a diversion controller. (See page 38.)
The FLEXmax maximum power point tracking (MPPT) function can be set to Auto Track or
U-Pick% mode as described on page 51. The MPPT function is based on the open-circuit
voltage (V
oc
) of the DC source. This is the unloaded voltage displayed by the source when it is
disconnected. MPPT values are expressed as a percentage of V
oc
. Auto Track mode allows
the FLEXmax to sweep the range of percentages. The Auto Track mode begins at the
maximum value and loads the array, working its way through lower voltages, until it locates the
input voltage that yields maximum wattage.
Auto Track Mode
The default minimum value of Auto Track is 1/2 (50% of V
oc
). The default maximum is 90% of
V
oc
. This is the standard maximum-power range for PV. A hydroelectric or fuel-cell system’s
operating voltage may operate in a different range and often have a maximum-power voltage
close to the battery voltage. The FLEXmax allows a user to set a sweep range more
appropriate for the source. The minimum setting can be changed to FULL, which is 40% of the
V
oc
. The maximum value can be set from 80% to 99% of V
oc
if necessary.
This adjustment only affects the initial tracking at the beginning of the day and any subsequent
trackings caused by Auto-Restart or any forced restart of the FLEXmax.
U-Pick Mode
If an optimal voltage is known for a given DC source, then this voltage can be set as a
designated V
oc
percentage in U-Pick% mode. This percentage is assigned in the Park Mpp set
point, which allows a range of 40% to 99% of V
oc
. If U-Pick % Voc is chosen, the FLEXmax will
load the source to operate continuously at the designated voltage. It will not sweep for the
maximum power point and will ignore all Auto Track values.