Gridzero - Outback FXR2012A Operator's Manual

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Mini Grid mode is also incompatible with the Grid Use Time and Load Grid Transfer functions of the MATE3
system display. These functions do not have similar priorities to Mini Grid or HBX, but they do control the
inverter's connection and disconnection with the grid. Mini Grid should not be used with these functions.
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When deciding whether to use Mini Grid mode or HBX, the user should consider the aspects of each.
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Mini Grid logic is based in the FXR inverter. After programming, it can function in the absence of the
MATE3. HBX logic is based in the MATE3. It cannot function unless the MATE3 remains operating.

Mini Grid can use utility grid power to fully recharge the batteries every time it reconnects to the grid.
HBX can only do so under specific circumstances.
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HBX set points have a wide range of settings. Mini Grid uses settings intended to protect the batteries
from excessive discharge; however, most of its settings are automatic and do not allow customization.
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HBX works more efficiently with a larger renewable source, but there is no specification for renewable
size. Mini Grid cannot work properly unless the renewable source is larger than the size of the loads. If
this condition is not met, Mini Grid will not disconnect the inverter from the utility grid.

Mini Grid is one of seven inverter-level functions (modes) which share a single input. Selecting it
prevents any other input mode from being used. HBX is a system-level function which can be
combined with the settings of other input modes.
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See Table 6 on page 54 for a comparison summary. Pages 53 and 54 have more information on HBX,
Grid Use Time, Load Grid Transfer, and other functions of the system display.

GridZero

In GridZero mode, the FXR inverter remains grid-connected, but prioritizes the use of battery or
renewable sources to run loads. It uses only renewable energy to recharge the batteries. The inverter
tries to "zero" the use of the utility grid, drawing on AC power only when needed to supplement
stored DC sources. Note that the inverter draws up to 1 Aac regardless of the DC sources.
In the MATE3 system display, the selectable options are DoD Volts and DoD Amps. The inverter sends
battery power to the loads when the batteries exceed the DoD Volts setting. (12-, 24-, and 48-volt
systems must exceed the setting by 0.2, 0.4, and 0.8 Vdc respectively.) As the battery voltage decreases
to DoD Volts, the inverter reduces the current toward zero. It will maintain the batteries at this setting.
The FXR inverter can manage large quantities of power. To prevent damage to the batteries from
rapid discharge, the rate of discharge can be limited using the DoD Amps setting. This item should be
set lower than the current provided by the renewable source.
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When DoD Volts is set low, this mode allows more renewable energy to be delivered from the batteries to
the loads. However, it will also leave less of a battery reserve in the event of a grid failure.
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When DoD Volts is set high, the batteries will not be discharged as deeply and will retain more of a backup
reserve. However, not as much renewable energy will be sent to the loads.
The renewable energy source needs to exceed the size of all loads and possible losses. The renewable
source must also charge the batteries. The inverter does not charge the batteries in GridZero mode.
BENEFITS :
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This mode seamlessly blends the use of battery power and grid power. It puts renewable energy to the
most effective use without selling power to the utility grid.
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GridZero mode minimizes dependence on the grid as long as certain conditions are met.
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The inverter remains connected to the utility grid in case the grid is needed. If large loads require the use of
grid power, no transfer is necessary to support the loads.
900-0167-01-00 Rev A
Operation
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