Eskom also warned of possible load-shedding last week.
The Sunday Times reported at the weekend that former Eskom boss Matshela Koko allegedly guaranteed multinational engineering company ABB R6.5bn in future contracts if it subcontracted work on the Kusile power station to Impulse International, a company part-owned by his stepdaughter.
The National Energy Regulator (Nersa) announced on Thursday that South Africans will pay 9.41% more for electricity in 2019/20, followed by an 8.1% increase for 2020/21 and another 5.22% hike for 2021/22.
Eskom had applied for hikes of 17.1% for 2019/20, 15.4% for 2020/21 and 15.5% for 2021/22.