TGOOD Australia has supplied two transformer skids to FlowPower for its Coonawarra BESS project in the Coonawarra region of South Australia. The in the first quarter of 2025 and Practical Completion was achieved in November 2025, following factory manufacture, testing, transport and on-site commissioning.
Project background
The Coonawarra project pairs a solar farm with a grid-scale battery energy storage system (BESS), giving FlowPower the ability to store solar generation and discharge it back to the grid when it is needed most, while also supporting frequency control and grid stability services in the region. TGOOD’s Coonawarra contract was awarded alongside a sister project at Monarto, South Australia, with both sites following the same equipment design and delivery program.
For Coonawarra, TGOOD’s scope covered the primary and auxiliary power infrastructure connecting the site’s battery containers and inverters into the wider distribution network, delivered as two purpose-built, transportable skids—the same proven configuration TGOOD has now deployed across multiple FlowPower BESS sites in partnership with Brunstock Australia.
Equipment supplied
TGOOD supplied a Brunstock 33 kV, 4.6 MVA main transformer skid, forming the primary step-up connection between the site’s inverter system and the grid. Alongside this, TGOOD supplied a second Brunstock 33 kV, 315 kVA auxiliary transformer skid incorporating a BGS 40.5 kV SF6-free ring main unit (RMU), housed in a weatherproof enclosure together with the associated secondary protection and control panels.
As with TGOOD’s other BESS projects, both units were fully assembled and factory-tested as complete skids before leaving the factory, rather than being built up on site. This limits the amount of live electrical work required in the field and gives FlowPower a consistent, quality-controlled outcome regardless of site access or weather. The SF6-free ring main unit also avoids the use of sulfur hexafluoride, a potent greenhouse gas used as an insulating medium in conventional switchgear, without any compromise to safety or protection performance.
On site, the transformer skids sit between the battery containers and inverters and the grid connection point, stepping down voltage for site auxiliary loads such as controls, communications and services, while the main transformer skid carries the bulk power exported from the BESS. Coordinating this interface with the inverter, control and battery equipment supplied by other vendors was a key part of our design process, requiring ongoing collaboration between Brunstock/TGOOD’s engineering team and FlowPower’s wider project and equipment suppliers.
A repeatable model for FlowPower’s BESS rollout
Coonawarra is one of several BESS developments FlowPower has underway, and TGOOD’s factory-first delivery model is well suited to a program of this kind. Rather than engineering each site from scratch, TGOOD carried the primary and secondary design developed for the first FlowPower site through to Coonawarra, adapting it where needed for local conditions while keeping the core transformer and switchgear configuration consistent. This let TGOOD move more quickly from contract award to manufacture, and gave FlowPower a predictable, repeatable outcome across sites rather than a one-off bespoke build.
For a battery storage developer running multiple projects in parallel, this kind of standardisation also simplifies spares holding, maintenance planning and operator familiarity, since site teams are working with the same equipment layout and control philosophy from one project to the next.
Engineering, manufacturing and testing
Delivery of the Coonawarra skids followed TGOOD’s standard project process: primary electrical design of the transformers and switchgear, followed by detailed secondary design covering protection, control and SCADA integration, with drawings issued to FlowPower for review and approval at each stage before manufacture began.
Manufacturing was carried out under TGOOD’s factory quality program, with the equipment progressing through defined inspection and test points, including prototype and type testing of the switchgear, wiring checks, and full Factory Acceptance Testing (FAT) prior to despatch. On arrival in Australia, the transformer and RMU skids underwent a further round of local inspection and testing, confirming the equipment had not been affected during transport and remained ready for installation, in line with TGOOD’s factory and local Inspection and Test Plans (ITPs).
This two-stage testing regime—full FAT in the factory, followed by local electrical work at our assembly facility in Rocklea Australia—is standard practice across TGOOD’s skid-mounted and containerised equipment, and is designed to pick up any issues well before the equipment reaches site, where rectification takes longer and costs more.
Delivery and commissioning
Once manufacturing and factory testing were complete, the transformer and RMU skids were shipped to Australia and finalised by TGOOD Australia’s local electrical team in our Rocklea assembly facility. After pre-commissioning the step-up skid stations were transported to the Coonawarra site for final installation. On-site commissioning was carried out jointly with FlowPower’s project team, covering electrical testing, protection relay commissioning, and integration checks with the site’s wider control and SCADA systems ahead of handover.
About FlowPower
FlowPower is an Australian energy retailer and renewable energy solutions provider, working with commercial, industrial and generation customers across the National Electricity Market. FlowPower supports its customers with electricity retail, power purchase agreements and the development of renewable generation and battery storage assets, helping drive the transition to a more flexible, lower-carbon grid.
About TGOOD
TGOOD is a global manufacturer of medium and high voltage electrical equipment including prefabricated substations, ring main units, gas-insulated switchgear and associated infrastructure. TGOOD supplies equipment to utilities, contractors and developers across transmission, distribution and energy storage applications. Visit TGOOD Australia’s completed projects list.
For enquiries about TGOOD’s substation kiosks and MV switchgear for Australian projects, contact our local team:
Email: australia@tgood.com
Phone (AU): 1300 061 299
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