Outback Power Systems FLEXmax 80 Owners Manual - Manual (Page 102)

Applications
100 900-0009-01-00 Rev C
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 35.)
The FLEXmax maximum power point tracking (MPPT) function can be set to Auto Track or U-Pick%
mode as described on page 48. The MPPT function is based on the open-circuit voltage (Voc) 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 Voc. 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 Voc). The default maximum is 90% of Voc.
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 Voc. The maximum value can be
set from 80% to 99% of Voc 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 Voc
percentage in U-Pick% mode. This percentage is assigned in the Park Mpp set point, which allows a
range of 40% to 99% of Voc. 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.