Product Manual

Operation
36 900-0161-01-01 Rev B
Offset
Offset
is an automatic operation which occurs in certain conditions. It is not a programmable
inverter function.
This operation uses excess battery energy to power the loads when an AC source is present.
The system can take advantage of renewable energy sources, “offsetting” dependence on the
AC source.
The battery voltage increases as a renewable energy source charges the batteries. When the
battery voltage exceeds a designated reference voltage, the Radian inverter begins inverting.
It draws power from the batteries (discharging them) and uses that power to offset the use of
the AC source.
The Radian inverter uses excess DC energy for this function under the following rules:

If the load demand is higher than the exported power, the inverter’s use of the AC source is reduced.
The exported amount of power has “offset” the same amount of demand on the AC source. (This is
sometimes known as “selling to the loads”.)

If the excess DC energy (and exported power) is equal or greater than the load demand, and the
Radian is in the
Grid Tied
input mode, the inverter will sell the additional power to the utility grid.
This is the key priority of the
Grid Tied
mode.
The Radian inverter uses several set points as reference voltages for the offsetting operation,
particularly the battery charger settings.

The charger settings
Absorb Voltage
,
Float Voltage
, and
Equalize Voltage
(as shown in the
system display) are all used as reference voltages. Normally the charger regulates to these set
points by adding power to the batteries. Offsetting does the opposite; it uses the same set points but
regulates the voltage by removing power from the DC side of the system.

If none of the battery charger’s timers are active, the reference voltage is
Sell Voltage
in the
Grid-Tie
Sell
menu. This is true in any input mode where
Offset
is used, not just the
Grid Tied
input mode.

The
GridZero
mode only uses a single reference voltage for
Offset
, the
DoD Volts
setting.
NOTES
:

The
Offset Enable
menu item must be set to
Y
(yes) for
Offset
to work.

Offsetting operation is available in the
Support, Grid Tied
, and
GridZero
modes.

Offsetting operation is available in the
Mini Grid
mode. However, it may not be used often since the
Mini Grid
priority is to avoid grid use.

Offsetting operation is not available in the
Generator, UPS,
and
Backup
input modes.
Table 3 Offset Interaction with AC Source
Mode Excess DC ≥ loads Excess DC < loads
Generator
Does not function
Support
Offsets load use, but also uses DC to support the AC source based on
Support
mode settings
Grid Tied Sells excess to AC source (grid); remains
connected
Offsets loads with whatever power is available
UPS
Does not function
Backup
Does not function
Mini Grid Offsets loads with whatever power is available; inapplicable if disconnected from utility grid
GridZero
Offsets load use, but only according to the
DoD Volts
setting