EPEC Group has been awarded a contract to cover the high-voltage connection works for the Lower Wonga Solar Farm in Queensland, Australia, by the EPC contractor INTEC Energy Solutions.
Under the contract, EPEC will handle the design, engineering, procurement, construction, testing and commissioning of a 275/33kV substation and an associated 275kV overhead line connecting the project to the Woolooga Powerlink substation.
Lower Wonga is located on the Wide Bay Highway in Queensland’s Gympie region. The project combines a 380MWdc solar PV power plant with a battery energy storage system (BESS).
According to project developer Lightsource bp, the plant pairs the solar array with a 281MW/843MWh BESS and is one of the largest co-located solar-plus-storage developments currently under construction in Australia, with commercial operations targeted for late 2028.
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The connection contract follows a series of supply and construction milestones at Lower Wonga over the past year.
Lightsource bp broke ground on the project in mid-2026, with the EPC contract for the solar and storage components handled under a joint venture between INTEC Energy Solutions and battery manufacturer Gotion Hi-Tech Australia.
In July, US tracker manufacturer GameChange Energy was selected to supply its Genius Tracker 1P Terrain Following system for the site, chosen for its ability to reduce earthworks across variable terrain, as well as hail-stow and generation optimisation technology.
Grid connection infrastructure of this kind typically constitutes one of the more complex and time-intensive elements of utility-scale project delivery in Australia, given the coordination required among developers, EPC contractors and network operators such as Powerlink Queensland.
EPEC’s scope covers the full chain from design through to energisation, work that determines when a project can begin exporting power and participating in the National Electricity Market.
Lower Wonga has also secured support through the Australian government’s Capacity Investment Scheme, which provides long-term revenue certainty for new generation and storage capacity, and Lightsource bp has signed a hybrid offtake agreement with mining company Rio Tinto to supply renewable energy to its Queensland operations from the site.
Part of a wider pattern of solar-plus-storage build-out
Lower Wonga forms part of a broader shift toward co-located solar and battery storage in Australia’s utility-scale market, as developers increasingly favour hybrid projects over standalone solar.
Lightsource bp has pursued a similar approach with its 450MW Goulburn River Solar Farm in New South Wales, which received federal environmental approval in 2024 and includes a 49MW/392MWh BESS.
The company’s strategy has also involved divesting standalone solar assets to concentrate on hybrid development.
In February 2026, Lightsource bp sold a 1GW portfolio of five operational solar PV projects in Australia to Aula Energy, with the company’s Asia-Pacific chief operating officer, Adam Pegg, noting that Lightsource bp has increasingly prioritised projects with a battery storage component as its regional strategy has evolved.
That shift has coincided with mounting curtailment across the National Electricity Market (NEM), which reached more than 7TWh in 2025, a year-on-year increase of over 60%, according to figures reported at the time.
Falling battery costs have also reduced the incremental cost of adding storage to new solar developments, a factor cited by industry figures as accelerating the transition from standalone solar to hybrid projects across the country’s utility-scale pipeline.
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