What is the difference between main meter and meter topology (parent-child)?

These are two related but distinct concepts that control different parts of the platform:

Main Meter (is_main_meter) controls the building overview consumption chart:

When set to true, the building overview chart uses only this meter's data for its energy type
Sub-meters of the same type are excluded from the chart to prevent double-counting
This is a simple on/off flag — it does not create any relationship between meters
Set it on the intake meter that represents total building consumption

Meter Topology (parent_meter_id) controls the hierarchy view in Analytics → Formula Meters:

Creates a parent-child tree showing how consumption flows from main meters to sub-meters
Enables unmeasured consumption calculation (parent minus sum of totalized children)
Allows visual hierarchy editing via canvas drag-and-drop or table dropdowns
Used for detailed sub-meter breakdown analysis

How they work together

A well-configured building typically has both:

The intake meter is marked as is_main_meter = true (so the building overview shows correct totals)
The same meter is the root of the topology tree with sub-meters as children (so you can drill into the breakdown)

Key difference: is_main_meter answers "what total should the building chart show?" while topology answers "how does consumption break down within the building?"

Example setup

Building main electricity meter: is_main_meter = true, parent_meter_id = null (root)
- Floor 1 meter: is_main_meter = false, parent = main meter, is_totalized = true
- Floor 2 meter: is_main_meter = false, parent = main meter, is_totalized = true
- Common area meter: is_main_meter = false, parent = main meter, is_totalized = true

Where to configure: is_main_meter → Analytics → Meters → meter detail. Topology → Analytics → Formula Meters → Canvas or Table view.