Kusile and Medupi, the third and fourth largest coal power plants in the world, were originally due to come online in 2014 and 2012 respectively, which would have given the country an extra 9 600MW of power, enough to avoid blackouts.
In 2019 both are still under construction.
When Eskom announced in 2007 that it was to build the two new mega coal power plants, the cost of Medupi was just under R70-billion and Kusile R80-billion.
The latest costs are now R208-billion for Medupi and R239-billion for Kusile.
While some of the units have come online and are generating electricity, they have been plagued by problems. Eskom calls these "design faults" and says it will cost R8-billion to rectify.
Some experts say that is par for the course with mega projects worldwide, now regarded as outdated because of the almost inevitable time delays and cost overruns that go with massive projects.
Others, while acknowledging this, say there was a lack of oversight and control over the projects from an early stage, which paved the way for corruption.
Energy expert Hilton Trollip of the University of Cape Town's (UCT's) Energy Research Centre, said there were serious problems with Medupi almost from the start, but they were not investigated.
When the problems around lack of transparency became systemic, National Planning Commissioner Anton Eberhard had recommended a probe, but nothing had been done.
"Once the conditions for both corruption and impunity had been established at the levels they were in Eskom, and as it become clearer that this impunity persisted, it became increasingly likely that things would develop along the path they have. By now there are so many beneficiaries, large and small, throughout the Eskom ecology, and the culture is so entrenched, that rooting them out within the existing institutional structure is not credible," Trollip said.
Jesse Burton from UCT’s Energy Research Centre agreed that corruption and State capture had been serious underlying factors in the delay and cost overruns of Medupi and Kusile.