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Entura celebrates major step forward for Tonga’s sustainability and electricity access

18 July, 2025

After 8 years of involvement and extensive efforts by more than 50 of Entura’s personnel, Entura is celebrating the successful conclusion of a transformational project in the Pacific.

The Tonga Renewable Energy Project – or TREP – is now revolutionising life for many small communities who have had little or no access to reliable electricity. It is also reducing the nation’s heavy reliance on imported diesel fuel.

TREP was established to provide more renewable generation and energy storage to increase electricity access, improve service quality and reliability, and support Tonga’s energy transition, climate resilience and environmental sustainability.

Tonga aims to be powered by 70% renewable energy by 2030. The nation comprises 171 South Pacific islands, 45 of which are inhabited, with a population of a little over 100,000.

The project – funded by the Asian Development Bank (ADB), Green Climate Fund (GCF) and Australia’s Department of Foreign Affairs and Trade (DFAT) – has delivered new solar and battery systems on Tongatapu (the main island), grid-connected renewable energy generation on ‘Eua and Vava’u islands, electrification of 9 outer islands with solar-battery systems, and capacity-building support.

“We are proud to have provided a range of expert support to this important project over an extended time, from inception to implementation,” said Entura’s Managing Director, Dr Amanda Ashworth.

Entura was initially engaged by the ADB to conduct technical, financial and economic feasibility assessments and due diligence on the key project components, supporting Tonga’s applications for project finance. This was followed by support for the tendering, evaluation and selection processes, resulting in construction contract award.

Subsequently, Entura was engaged as construction supervision consultant for TREP. In this role, Entura provided a full Owner’s Engineer suite of services including design review, procurement verification, factory inspection and test witnessing, inspecting site works, witnessing and reviewing completion and commissioning tests, reviewing EPC contractors’ management plans and quality assurance, as well as monitoring and reporting on environmental, social and gender safeguards.

Entura’s capacity-building activities for TREP included a range of training that supported capability uplift in tariff policy/approaches, development of operations and maintenance (O&M) plans, and building skills in power modelling, control systems and SCADA within the utility.

“All the training we provided had, at its heart, the future sustainability of operating and maintaining renewable energy systems in Tonga,” said Dr Ashworth.

Entura’s work has now concluded, and TREP was officially deemed complete at the end of June 2025.

All TREP project outputs have been achieved. Both battery energy storage systems (BESS) in Tongatapu are operating, providing storage for excess solar and being controlled automatically by the new generation and distribution management system. ‘Eua and Vava’u main islands are running at higher contributions of renewable energy.

Nearly 500 households across 9 islands have been provided with 24/7 grid electricity for the first time, powered only by solar and battery systems.

“For our people involved in TREP, seeing life-changing benefits emerge from our work is deeply satisfying,” said Dr Ashworth. “The project has created new employment opportunities for Tongans, including many women who have been trained as carpenters, electricians and line workers. Thanks to reliable electricity and new electric appliances, many community members have reported being able to better manage their work-life balance and studies, start micro-businesses that use electric appliances, earn more income, and eat fresher food.”

Dr Ashworth says that Entura’s contribution to TREP demonstrates the practical implementation of the business’s vision of ‘a sustainable energy future for all’.

“Through our involvement in TREP, we’re proud to have furthered Tonga’s goals of improving lifestyle, health, educational and financial outcomes,” said Dr Ashworth. “We remain deeply committed to making a significant contribution to the global energy transition and our Pacific neighbours.”

Entura has provided specialist support for renewable energy solutions across the Indo-Pacific region, including energy roadmaps, hybrid renewable microgrids, and capacity building in the Federated States of Micronesia, Tuvalu, Cook Islands, Solomon Islands and Marshall Islands.

For more about TREP, read our TREP case study, or see Tonga Power’s website, the TREP Facebook page and the ADB website.

Find out more about Australia’s commitment to strengthening climate and disaster resilience in the Pacific here.