This report was prepared by the Asian Development Bank and Tonga Electric Power Board. The Asian Development Bank (the Bank) is providing a technical assistance grant to the Government of Tonga for financing consulting services to define the next phase of the Tonga Electric Power Board's (TEPB) power system development program. Monenco AGRA Inc was engaged by the Bank to provide the consulting services. The main goal of the Second Power Development Study is to define the next phase of TEPB's generation and distribution development program and formulate a project for possible Bank financing.