For the first time on Sunday Kusile Unit 3 produced power, according to an internal memo to Eskom staff.
According to the note from Eskom's chief operating officer Jan Oberholzer, sent out to staff on Monday, the synchronisation of the unit happened eight months ahead of the scheduled December 2019. This is the third out of six Kusile units which have been synchronised to the national grid.
"The first synchronisation of Unit 3 marks a key milestone towards the full commercial operation of the unit.
"The next step will be the testing and optimisation of the unit which will result in it generating full power of 800MW of electricity, to be fed into the national grid for the country's consumption," Oberholzer said.
The unit is expected to be commercially operational, six months after the first synchronisation - or November 2019.
The first Kusile unit went live in August 2017. Each of the six units will produce 800MW of electricity, Fin24 previously reported.
At a previous briefing earlier in April on the status of the electricity system, Eskom board chair person Jabu Mabuza said that the construction of Kusile and Medupi Power stations would not be halted. The construction of both plants costs R36bn (R18bn each).
Mabuza explained that the benefit of concluding construction would outweigh the cost of stopping the projects.
Construction started as far back as 2007.