Outback Power Systems FLEXmax Extreme Owners Manual - Manual (Page 77)

Applications
900-0150-01-00 Rev A 75
Grid-Interactive Settings
When using an OutBack inverter, FLEXmax Extreme, HUB Communications Manager, and system display, set
the Grid-Tie Mode menu to Y in the system display. This mode allows the inverter to manage the charge
controller’s Float setting. It ensures the controller always keeps the battery above the sell voltage of the inverter.
(See page 39.)
When using a FLEXmax Extreme charge controller with an inverter without the use of a HUB, GT mode will not
work because the charge controller cannot communicate with the inverter. In this situation, when selling
electricity back to the grid, keep the inverter’s “sell” voltage setting below the charge controller’s Float setting.
In a 24-volt battery system, the difference should be at least 0.5 Vdc. In a 48-volt system, the difference should
be at least 1.0 Vdc.
Hydroelectric and Fuel Cell Applications
Performance Optimization
The FLEXmax Extreme 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.
Using the MATE3 system display, the maximum power point tracking (MPPT) function can be set to Auto or
U-Pick VOC mode. (See page 37.) 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 mode allows the FLEXmax Extreme to sweep the range of percentages. The Auto 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 is Half (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 Extreme 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 Extreme.
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 U-Pick VOC set point, which allows a range of 40% to 99% of
V
oc
. If U-Pick is chosen, the FLEXmax Extreme 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 values.