Shave a demand peak
Scope
A peak shave rule lowers the grid import ceiling during set hours. Thus the battery supplies the load. See Build a rule list and What a rule condition can read field definitions.
Location
- Path: My Devices, Plant Control, then the Diagram tab.
- Settings: in the three-dot menu of the diagram, set Edit to on. Then double-click the point.
Permissions
- See the settings: all access levels. A Viewer double-clicks a device on the diagram and sees its settings without the Save button.
- Change and save the settings:
Editor,InstallerorFull control.
Step 1: Storage Point
- On the Target Power tab, set the Default to a charge. A charge is a negative value.
- Give the Default a Grid/Storage Priority equal to or higher than the grid Target Power Default.
- Add the hold rule below, with the same Grid/Storage Priority.
- Click Save.
| Hours | Condition | Value |
|---|---|---|
| Peak window | Storage % <= floor | small charge |
- Priority: the battery leads the loop and charges again when the time is not in the peak hours. If the grid has the higher priority, the battery follows the grid Target Power. See How plant control works.
- Hold rule: without it, the charge Default charges the battery from the grid during the peak, after the floor.
Step 2: Grid Point
- On the Basic tab, set Rated Power to the physical maximum of the grid connection.
- On the Max Limit tab, set the Default to the usual import ceiling, in W.
- Add the peak rule below, and set Must hold for.
- Click Save.
Examine the peak rule before you click Save. The logger applies it at the next control cycle and starts to discharge the battery with no confirmation step.
| Hours | Condition | Value |
|---|---|---|
| Peak window | Storage % > floor | 0 |
- In the window, above the floor: the import ceiling is 0 W. PV and the battery supply the load.
- At the floor: the rule stops. The Default ceiling applies for the rest of the window.
- Must hold for: one short change of the reading at the floor does not change the ceiling.
Troubleshooting
- The rule applies at incorrect hours: the window includes midnight. Split the window into two rules.
- Grid import changes between 0 and the ceiling again and again during the peak: the battery hold rule is missing.
- The battery does not charge again when the time is not in the window: the battery Default is not a charge, or the grid has the higher priority.
Tips and Gotchas
- A single rule with From after To applies only from To to From, at the opposite times. For a window that includes midnight, make one rule to 23:59 and one rule from 00:00, with the same condition and value.
- The ceiling is a control target, not a breaker. If the battery cannot supply the load, the grid supplies the rest.
- The Max Limit list has no priority column.