Eskom has linked unit four of its Medupi coal power station, which has been marred by delays, to the grid, the State-owned power utility said on Tuesday.
The coal-fired unit in South Africa's Limpopo province is a rare example of a Medupi project that has been completed ahead of time. It was scheduled for completion in July of 2018.
Medupi will contribute 794 MW to the national grid and join the already linked units five and six, Eskom said in a statement.
Medupi, which was started in 2007 in an effort to boost the national electricity supply, has been plagued by labour disruptions, technical faults and cost overruns.
South Africa had regular power cuts in 2015 that hit key industries when demand exceeded capacity.