It accounted for 13 percent of total power generation, behind coal-fired power at nearly 50 percent and hydropower at 23 percent, according to a recent report by national utility Vietnam Electricity (EVN).
Total power generation rose 4.1 percent year-on-year to 59.65 billion kilowatt-hours, the report said.
Hydropower generation rose 55 percent year-on-year, while that of gas and coal fell 21 percent and 12 percent, respectively.
EVN has announced plans to cut solar and wind power generation by up to 1.74 billion kilowatt-hours in the second half of this year to deal with national grid overload.
It is installing the third circuit of the 500 kilovolt north-south transmission line, the backbone of the grid, which has been operating since 1994.