Interconnector Watch: Saturday 6 June 2026

Across the NEM at 06:30 AEST, the most significant interconnector story is Heywood (V-SA), which is binding at 529 MW toward South Australia against an export limit of 533.44 MW — utilisation of 99.2%. This is directly consistent with SA's price sitting at $124.33/MWh, the highest of the mainland regions, while Victoria clears at $110.50/MWh. The $13.83/MWh spread reflects the cost of sourcing the marginal MW into a constrained SA network, and with Heywood at its effective ceiling, there is no headroom to arbitrage that differential away. The constraint notice from 2 June confirms AEMO has been conducting internetwork testing on Heywood with a temporary SA-to-VIC test limit raised to 600 MW, but current flow direction is VIC-to-SA and the binding constraint is on the export side at 533.44 MW. Murraylink (V-S-MNSP1) is also flowing VIC-to-SA at 51.69 MW against an export limit of 62.82 MW — 82% utilised — providing a supplementary path into SA but with limited additional capacity available.

On QNI (NSW1-QLD1), flow is 896.75 MW northward from NSW into Queensland, representing 82% of the import limit of 1,090 MW in that direction. This flow is consistent with Queensland pricing at the lowest mainland level of $105.50/MWh against NSW at $122.30/MWh — Queensland's lower-cost generation is not the direction of flow here; rather, NSW surplus is moving north to serve Queensland demand of 5,996 MW. The $16.80/MWh NSW-QLD spread is the widest mainland differential and is being compressed but not eliminated by QNI's substantial northward transfer. QNI is not binding against its 1,090 MW import limit, so further flow is theoretically available, though the two lightning-related reclassification notices from 2 June — affecting the Armidale–Dumaresq and Armidale–Sapphire WF 330 kV lines — have since been cancelled, and constraint set N-ARDM_ARSR_1PH_N-2 has been revoked, removing a prior restriction on QNI and the DirectLink MNSP.

VIC-NSW (VIC1-NSW1) is carrying 379 MW northward from Victoria into NSW, at 43.7% of its 867.4 MW export limit — well below its ceiling and not binding. This flow aligns with Victoria's $110.50/MWh price undercutting NSW's $122.30/MWh, with the $11.80/MWh spread driving a predictable southward arbitrage opportunity that the market is partially but not fully exhausting. It is worth noting that a negative settlement residue constraint (NRM_VIC1_NSW1) was active on 1 June but ceased at 20:00 that evening; no equivalent constraint is currently active on this interconnector. Basslink (T-V-MNSP1) is at zero flow with Tasmania pricing at $87.24/MWh — the lowest in the NEM — and a $23.26/MWh differential to Victoria. With Basslink's export limit at 125 MW and no flow occurring, traders should monitor whether this persists through the morning peak or whether the Tasmanian