Gridzero - Alpha OutBack Power Radian Series Operator's Manual

Operation

GridZero

In GridZero mode, the Radian 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 grid use, 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 a MATE3-class system display, the selectable options are DoD Volts and DoD Amps. Any
time the batteries exceed the DoD Volts setting by 0.8 Vdc, the Radian will send power from
the batteries to the loads. As the battery voltage decreases to the DoD Volts setting, the
inverter will reduce the rate of flow toward zero. It will maintain the batteries at this setting.
The Radian inverter can manage large quantities of power. To prolong cycle life and increase
battery capacity, 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.
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 battery reserve in the event of a grid failure.
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 energy demand 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:
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.
GridZero mode minimizes dependence on the grid as long as certain conditions are met.
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.
This mode utilizes the Grid Support settings. See page 37 for more information on this function.
NOTES:
IMPORTANT:
Setting DoD Volts too low will severely discharge the batteries. The battery bank may not
have sufficient reserve to provide backup in the event of a grid failure. To prevent the loss
of power, load use and the DoD Volts setting should be planned accordingly.
If the renewable energy source is not greater than the size of the inverter loads, this mode will not
work well over time. The renewable source must be capable of charging the batteries as well as
running the loads. This occurs when renewable energy production exceeds the DoD Amps setting.
The inverter will offset the loads with excess renewable energy if it is available from the batteries.
See page 36 for more information on Offset operation. However, the behavior of Offset in GridZero
mode is different because it uses the DoD Volts exclusively.
The inverter's battery charger cannot be used in this mode. However, the charger menu settings and
timer operations are not changed when this mode is selected.
The battery should be discharged whenever possible in the attempt to "zero" the grid usage. If the
DoD Amps setting (or load demand) is too low, the renewable source will be prematurely curtailed.
The system will be unable to use the renewable energy and will then be more dependent on the grid.
The DoD Amps setting should be raised periodically until the renewable energy is fully utilized.
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