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What do I need to know about technical diagrams for inverter energy systems?

Single line diagram

A single line diagram (SLD) needs to contain information on the installation wiring from the point of supply off the Western Power network, through to all the inverters on site, including where the customer’s load is connected. 

It also needs to contain information on all protection devices and switches, as well as any communications required to achieve the desired operation of the system (i.e. self-consumption, export limit, etc.).

SLDs must use correct electrical symbols and should contain at least, but not limited to, the following information specific to the site in question:

  • Point of supply off the Western Power network
  • Western Power meter
  • show site main switch is a circuit breaker rated to the sites supply allocation (or will be at time of installation)
  • any private/customer smart meters
  • distribution boards
  • loads
  • all inverters – new and existing
  • energy source (PV array, batteries, etc.)
  • any communications and controls/monitoring equipment*
  • protective devices
  • cable size and length between all the above
  • description of the working/operational philosophy of the proposed system

* Where monitoring equipment is required for site generation limiting or self-consumption control, the following need to be indicated in the SLD:

  • monitoring equipment such as Current Transformers (CT) or energy meters
  • the phase/s that the equipment is monitoring
  • any links between the monitoring device and the battery storage device (refer to sections 2.1 of the Battery Inverter Energy System (IES) Requirements for more details)

Electrical symbols - AS/NZS 3000:2018

Switch (general symbol)

Transformer (single line)

Mechanically interlocked changeover switch

Switch disconnector (on-load isolating switch)

Disconnector (isolator)



Circuit breaker

Circuit breaker, earth leakage type, current operated (RCD)

PV array



3 pin socket outlet or cord
extension socket

Protective earth neutral (PEN) conductor

3 pin socket inlet or plug

Neutral conductor (N)

Protective earthing conductor (PE)

Connection to earth

Generation frame connection

Earth or neutral bar

Whole current (direct connecter)meter (non CT)

LV current transformer meter (LV CT)

HV current transformer metering unit (HV CT)

Connection block

Combination fuse switch

LV links or HV/LV load disconnector

Drop out fuse (DOF)


Site diagram

Identify on an aerial site diagram e.g. Landgate property search photo:

  • supply type (overhead or underground)
  • property/lot boundaries
  • point of supply for the private installation:
    • if underground, Western Power pillar/dome
    • if overhead, mains connection box (typically next to point of attachment) or
    • Western Power distribution substation e.g. transformer kiosk (strata and larger commercial)
  • if overhead supply, the Western Power service cable run from the network to point of attachment
  • transformer in rural or sole use cases
  • Western Power meter

Examples of site diagrams

Example site diagram

Example site diagram

Example site diagram

 Example site diagram