TGOOD Australia has supplied two transformer skids to FlowPower for its Monarto BESS project in Monarto, South Australia, as part of the customer’s broader renewable energy and battery storage program. The equipment was contracted in December 2024, the project commenced early in 2025 and Practical Completion was achieved on in October 2025, following factory manufacture, testing, transport and on-site commissioning.
Project background
The Monarto project forms part of FlowPower’s growing portfolio of battery energy storage system (BESS) developments supporting the National Electricity Market. Grid-scale batteries like this one help firm up variable renewable generation, provide fast-response grid services, and allow energy to be stored when it is abundant and cheap and dispatched when it is needed most. Projects of this type increasingly rely on compact, factory-built power infrastructure that can be manufactured, tested and shipped as complete units, minimising the amount of specialist work required on site and shortening overall project timelines.
For Monarto, TGOOD worked in partnership with Brunstock Australia, which also supplied the energy storage system for the solar farm. Our scope centred on the primary and auxiliary power infrastructure connecting the site’s battery containers and inverters into the wider distribution network, packaged as two purpose-built, transportable skids.
Equipment supplied
TGOOD supplied a Brunstock 33 kV, 4.6 MVA main transformer skid, which forms the primary step-up connection between the site’s inverter system and the grid. Alongside this, TGOOD supplied a second 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.
Both units were designed and built as fully assembled, factory-tested skids rather than being constructed piecemeal on site. This approach reduces on-site installation time, limits the amount of live electrical work required in the field, and gives the customer a consistent, quality-controlled outcome regardless of site conditions. The use of SF6-free switchgear technology in the RMU also supports FlowPower’s sustainability objectives, eliminating the use of sulfur hexafluoride—a potent greenhouse gas commonly used as an insulating medium in conventional switchgear—without compromising on safety or performance.
On site, the transformer skids connect into the broader BESS power train, stepping down grid voltage for the site’s inverter and battery systems and supplying auxiliary loads such as controls, communications and site services. This kind of interface work—matching Brunstock’s primary and secondary design to third-party inverter, control and battery equipment supplied by other vendors—is a routine but critical part of delivering DER infrastructure, requiring close coordination between TGOOD Australia/Brunstock’s design team and FlowPower’s broader project and equipment suppliers throughout the design phase.
Why prefabricated substations for BESS projects
Battery storage developments like Monarto typically operate on tight construction schedules, with civil works, battery containers, inverters and grid connection infrastructure all needing to come together on a fixed timeline. Prefabricated, skid- and kiosk-mounted substations are increasingly the preferred approach for this kind of work because the bulk of the electrical assembly, wiring and testing is completed under controlled factory conditions rather than in the field. This shifts risk away from the site—where weather, access and sequencing with other trades can all cause delays—and into a factory environment where TGOOD can closely manage quality, schedule and safety.
For a customer running multiple BESS developments concurrently, as FlowPower is, this repeatable, factory-first delivery model also makes it easier to standardise design, procurement and commissioning practices across sites, supporting a more predictable rollout as each project moves from contract award through to energisation.
Engineering, manufacturing and testing
Delivery of the Monarto skids followed TGOOD’s standard project process, beginning with primary electrical design of the transformers and switchgear, followed by detailed secondary design covering protection, control and SCADA integration. Design documentation was issued to FlowPower for review and comment at each stage, with drawings progressively updated and approved before manufacture commenced.
Manufacturing was carried out under Brunstock’s factory quality program, with 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 to confirm the equipment had not been affected during transport and remained ready for site installation, in line with TGOOD’s factory and local Inspection and Test Plans (ITPs).
This staged testing regime—factory FAT followed by local re-verification—is standard practice for TGOOD’s containerised and skid-mounted equipment, and is intended to catch any issues well before equipment reaches site, where rectification is more time-consuming and costly.
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. Finally they were transported to the Monarto 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 before the equipment was handed over.
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 and Brunstock’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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