It did not disclose the terms of the deal.

Zach Struyk, senior director of SunPower's East Asia operations, told Recharge at PV Japan 2014 that the order is the company's biggest so far in Kyushu.

Independent power producer (IPP) Nangoku did not say when it expects to finish building the solar plant in Hioki, Kagoshima prefecture.

It chose California-based SunPower's E20/327 panels because it felt that they would be the most efficient modules to use in the hilly, constrained confines of the northern end of the Satsuma peninsula, where the project will be situated, Kagoshima-based Nangoku said in an online statement.