Peak Load Shaving; Time-Of-Use Metering - Xantrex XW4024-120 Operation Manual

Peak Load Shaving

Time-of-Use Metering

975-0240-01-01
Grid support enabled, Sell enabled In this mode all available excess DC
power is first used to power local loads, and any excess is exported to the utility
grid.
Note:
Running and Start-up (Peak) currents are limited to the maximum current limits
of the inverter.
Many utilities impose a surcharge on their customers based on the peak load used
by a facility. To reduce utility peak demand charges, the inverter can be
configured (using the Load Shave Amps setting) to limit the maximum draw the
AC loads place on the utility. The inverter can be programmed to provide power
above a specified level, eliminating the surcharge. When the utility current draw
reaches the maximum level, the inverter assists by providing battery powered AC
to the loads.
For Peak Load Shaving to be effective, all loads must be connected to the inverter.
For large loads, multiple (or stacked) inverters may be required.
To further ensure the batteries are able to supplement the power requirements of
the connected load, an additional source of power (solar, wind or hydroelectric) is
recommended.
Peak Load Shaving can also be used in addition to the time-of-use metering.
Utilities use time-of-use metering to determine utility charges during peak usage
hours and to impose a surcharge. The XW Inverter/Charger can be configured
(using the Load Shave Start, Load Shave Stop and Charger Block settings) to
overcome these peak charges by using utility power to charge the battery bank
during the inexpensive energy hours and consuming the battery energy during
expensive energy hours.
For example, if Charger Block is set between 9:00 AM and 10:00 PM and Load
Shave is set between 6:00 PM and 9:00 PM, charging on AC1 stops at 9:00 AM
and continues to pass utility AC through to the loads. If charging is required
during the charger block period, and AC Priority is set to AC2, the XW Inverter/
Charger can use any AC source connected to AC2. Loads will transfer to the AC
source on AC2 as well. The inverter connects to the utility grid at 6:00 PM and
supports loads using the batteries. The inverter continues to run until 9:00 PM.
The XW Inverter/Charger then stops supporting the utility grid and passes utility
AC through to the loads. At 10:00 PM utility AC begins maintaining the batteries
based on the battery charger settings.
The above example allows an external renewable energy source to be utilized as a
primary charging source during a desired time window. The charger (using utility
AC connected to AC1) can then be used to supplement the battery charging when
the rates utility rates are low.
Grid Support Settings
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