Assessment criteria

Some applications to connect a micro embedded generating (micro EG) unit to our network require a technical assessment. This is because we have an obligation to operate, maintain and protect our network to ensure the adequate, economic, reliable and safe connection and supply of electricity to our customers.

These assessments can also help customers avoid over-investing in systems that are too large to operate effectively at their point in the network.

Why some applications need to be technically assessed

Micro EG units have the potential to compromise the efficiency of the electricity network and cause voltage levels to fall outside the statutory ranges.

An inverter capacity that is too large will trip off when the voltage rises above the set limit, and the system will not generate or export to the grid until the voltage comes back into an acceptable range.

Assessment thresholds

We may require up to eight weeks to technically assess applications for total inverter capacities rated greater than:

• 5 kVA exporting for a single and two-phase premises on our network
• 15 kVA exporting for a three-phase inverter on a three-phase premises on our network
• 2 kVA exporting on SWER networks
• 0 kVA exporting or non-exporting on Isolated networks.

For total inverter capacities up to and including these thresholds, a minority will require assessment due to high PV penetration locally.

Assessments will not be required on applications for non-exporting total inverter capacities:

• up to 30 kVA on the Main network
• up to 10 kVA on the SWER network

All proposed connections, including for non-exporting and battery units, still require an application and an offer from us before installation can occur.

Please note:

• If an application isn't assessed, that does not imply our guarantee of effective operation
• It remains the installer's responsibility to do their testing and be confident the proposed micro EG unit will meet customer performance expectations
• Similarly, our assessment and any subsequent offer are provided at a point in time and are not a guarantee a unit will operate effectively
• The Mount Isa-Cloncurry network is a combination of three-phase and SWER network and is not treated as an isolated network in the context of micro EG unit applications.

Applications to connect an embedded generating unit larger than 30 kVA must be made through our Major business connections group.

We reserve the right to assess any application and to change these thresholds at any time.

The technical assessment process

Our initial evaluation considers the capacity of the inverter, the attributes of the local network servicing the premises, and the penetration of other micro EG units on the local network. If that initial evaluation identifies a risk, a full desktop assessment is undertaken.

The assessment references information including:

• The National Metering Identifier (NMI) number for the premises
• The Registered Plan (RP) number and Lot number of the premises
• The capacity of the inverter
• The capacity of the distribution transformer and local network that supply the premises
• The total capacity of individual micro EG unit already connected to the same transformer.

Occasionally, we may need to visit the premises and inspect the local network serving it to check the attributes of particular parts, particularly in rural areas.

Assessment exclusions

The assessment does not consider:

• The condition of the household wiring. To determine whether the existing wiring is suitable for the proposed micro EG unit, we encourage customers to engage a licensed electrical contractor
• The number of solar PV panels that are planned for installation. The assessment only considers the capacity of the inverter, which determines the maximum amount of electricity that can be exported to the network at any point in time
• The amount of electricity that is typically used by the occupants of the premises during the day.