EPEC Group takes grid connection contract for Lightsource bp's 843 MWh Lower Wonga project in Queensland

EPEC Group has been awarded the high-voltage grid connection contract for the Lower Wonga Solar Farm in Queensland's Gympie region, appointed by EPC contractor INTEC Energy Solutions on behalf of developer Lightsource bp.^[1] The project pairs a 380 MWdc solar array with a 281 MW / 843 MWh battery energy storage system and is targeting commercial operations in late 2028.^[1]

What EPEC will build

Under the contract, EPEC will design, engineer, procure, construct, test and commission a 275/33 kV substation and an associated 275 kV overhead transmission line connecting the site to the Woolooga Powerlink substation.^[1] That connection point determines when the project can begin exporting power and participating in the National Electricity Market (NEM).^[1]

The scope covers the full chain from design through to energisation - work that, in Australia's utility-scale market, is typically one of the more time-consuming elements of project delivery, requiring close coordination between the developer, EPC contractors, and the network operator Powerlink Queensland.

Project structure and supply chain

Lower Wonga sits on a 600-hectare site along the Wide Bay Highway near Gympie, on previously cleared grazing land adjacent to the Woolooga substation and transmission corridor. Lightsource bp commenced site works in mid-2026.

The solar and storage EPC work is being delivered through a joint venture between INTEC Energy Solutions and battery manufacturer Gotion Hi-Tech Australia. Key supply-chain appointments to date include:

• Grid connection: EPEC Group (substation and 275 kV overhead line)
• Solar and BESS EPC: INTEC Energy Solutions / Gotion Hi-Tech Australia JV
• Solar tracker: GameChange Energy (Genius Tracker 1P Terrain Following system, appointed July 2026)

The BESS provides approximately three hours of storage duration, sized at 281 MW / 843 MWh.

Revenue stack

Lower Wonga has secured two layers of revenue certainty. Lightsource bp has signed a hybrid offtake agreement with Rio Tinto covering 40% of the project - equivalent to 112 MWac of solar capacity and approximately three hours of associated battery storage - to supply renewable electricity to Rio Tinto's Queensland operations. That deal forms part of Rio Tinto's broader effort to decarbonise its Boyne aluminium smelter at Gladstone, where total contracted Queensland renewable power now exceeds 2.8 GW.

The project has also secured support under the Australian government's Capacity Investment Scheme (CIS), which provides long-term revenue certainty for new generation and storage capacity.^[1]

What to watch

Lower Wonga is one of the largest co-located solar-plus-storage projects currently under construction in Australia.^[1] Lightsource bp reports a pipeline of more than 9.5 GW of solar, wind, and storage projects across the Asia-Pacific region. The grid connection milestone is the critical path item: energisation of the 275 kV line and substation will set the earliest date the project can begin NEM dispatch, making EPEC's delivery schedule the key variable between now and the late-2028 commercial operations target.