Conext SW 4048-120 Manual Addendum

Documentation Update
2 976-0315-01-01 Rev E
Conext SW New Features
Load Shaving
Load shaving (Load Shave) allows the CSW to support (or assist) the AC source
in powering local loads during a defined window of time (LoadShaveStart and
LoadShaveStop). See “Time-of-Use Metering” on page 3. It allows the inverter to
control how much current can be drawn from the AC source. When the CSW
inverter detects that the AC input current is over a set limit called Load Shave
Amps, it uses battery power to limit the peak load on the AC Input by providing the
difference in amps between the actual load current and the current limit set in
Load Shave Amps. However, when the battery is in charge mode, the total AC
input current is limited by 80% of Load Shave Amps to avoid the quick swing
between battery charge and discharge. This quick swing phenomenon is
described in the following instance.
If the AC input current limit is the same value as Load Shave Amps in battery
charge mode, the charge current can be higher than the limit value due to
the charge dynamics. Under this condition, the battery will enter into
discharge mode because the AC current is higher than Load Shave Amps.
After the battery is in discharge mode, the battery will go back into charge
mode again because the load current is smaller than Load Shave Amps.
Therefore, the battery will be in the charge and discharge modes back and
forth - the quick swing. In order to avoid this phenomenon, a hysteresis band
is set by limiting the AC input current to 80% of Load Shave Amps when the
battery is in the charge mode.
When Load Shave is enabled and within LoadShaveStart and LoadShaveStop
times, it will automatically transition into and out of load shaving operation.
• To transition into the load shaving state, the inverter must first detect that the
AC Input current exceeds the Load Shave Amps. It will then turn on the
inverter and source current so that the AC Input current matches exactly the
current in Load Shave Amps.
• To transition out of the load shaving state, the inverter detects that the input
current is below the Load Shave Amps and it no longer needs to support the
loads with power from the battery.
In a grid-interactive backup system Load shaving combined with time-of-use
metering helps reduce utility peak demand surcharges.
In an off-grid system with generator Load shaving can be used to support the
generator. If the generator is unable to provide enough current to run loads in the
system, load shaving ensures that the system does not exceed the generator’s
current rating. This is done by matching the generator’s manufacturer
recommended current rating with the Load Shave Amps setting.
See “Load Shave Setting” on page 14 for a sample scenario.