Chinese solar panel maker Trina Solar is planning to invest an additional $420 million in Vietnam's northern province of Thai Nguyen, raising its total investment in the country to nearly $900 million, the provincial government said on Sunday.

Reuters in September exclusively reported that Trina, one of the world's biggest solar panel makers by sales, would invest $400 million in a new plant in Vietnam.

In a statement released after a meeting between Trina's chairperson Gao Jifan and Deputy Prime Minister Tran Luu Quang, Gao said he expected to get support from the authorities to research and invest in rooftop solar power projects locally.

Trina, which was founded in 1997, is one of the biggest solar panel makers in Vietnam and operates two plants in Thai Nguyen, about 82 km from capital city Hanoi.

The statement did not say whether the investment would include a third Trina Vietnam facility, or whether it could be used for other projects such as expanding existing plants.

Trina's Vietnam investment follows an investigation by the U.S. Department of Commerce that concluded in August Trina was among five Chinese solar firms who used plants in Thailand and other Southeast Asian countries to dodge punitive tariffs on Chinese-made panels.

China and Hong Kong combined were the biggest foreign investor in Vietnam in the first 10 months of this year, according to Vietnamese government data.