The Asian Development Bank and Australia are to fund and install solar power systems on nine of Tonga's outer islands.
The project aims to provide a clean, affordable supply of electricity and trim the country's imported fuel bill.
It follows the establishment of a solar energy farm on the main island Tongatapu a year ago, providing 4 percent of the island's energy needs.
The Outer Islands Renewable Energy Project will fund solar systems on Eua, Vava'u and Ha'apai, along with four outer islands in the Ha'apai group, as well as on Niuatoputapu and Niuafo'ou.
The ADB will provide a two million US dollar grant while Australia's AusAID will give four and a half million with the Tonga government making a contribution of 300 thousand dollars.
The project will build solar generating facilities able to generate up to 1.25 megawatts anc cut diesel imports by nearly half a million litres a year.