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Asian Development Bank

100 Climate Actions from Cities in Asia and the Pacific


Tonga’s renewable energy project is combining investment in grid-connected renewable energy generation, battery energy storage systems, hybrid systems, and capacity building.

The $53.2 million project will install 650 kilowatts (kW) of grid-connected solar photovoltaic (PV) capacity with 1.4 megawatt-hours (MWh) battery storage on the islands of ‘Eua and Vava’u, and mini-grids totaling 501 kW PV with 4.3 MWh storage in the five outer islands of O’ua, Tungua, Kotu, Mo’unga’one, and Niuafo’ou.



To absorb additional 22 MW of PV and wind power systems to be funded by independent power producers, the project will also install in the capital Nuku’alofa, the country’s first large-scale battery systems. The batteries, with a total capacity 19.9 MWh, will store excess renewable energy to supply demand when the sun is not shining. This smart use of battery systems will enable Tonga to increase renewable energy penetration close to 50% nationwide without negatively affecting the island grids.

The investments will avoid over 13,000 tons of CO₂ equivalent emissions annually. The final project component focuses on capacity building, which will help the country to better plan for the green transition to reduce reliance on imported fossil fuels and encourage private investment in renewable energy projects.

The project was funded through an ADB grant of $12.2 million, a Government of Australia grant of $2.5 million, a Green Climate Fund grant of $29.9 million, and government counterpart financing of $8.60 million.

Tonga has a total of 1,151 kilowatts of new grid-connected PV capacity and over 20 MWh of battery energy storage on the main island of Tongatapu and 7 outer islands (photo by Andrew Richard Kautoke).

The Challenge

While 97% of households in urban areas in Tonga have access to electricity, about 90% of this power generation is from imported diesel. Transitioning to cleaner energy sources will help the government meet their 70% renewable energy target by 2030.


Economic The project will help to reduce the cost of levelized electricity from $0.40 to $0.30 on Nuaru by reducing the reliance on expensive, imported fuel.

Social The renewable energy project will increase clean energy access of marginalized populations by about 3% in the outer islands, where access is limited.