The high cost of Eskom using diesel turbines to provide electricity has to be weighed against the cost of load-shedding to the economy.
Since 2008 when wet coal led to the country's mines being shut down, it has been clear that the country has been in an energy crisis.
The Johannesburg Stock Exchange has introduced contracts that allow investors to protect against changes in diesel prices.
The price of all grades of petrol will increase by 39 cents, and all grades of diesel by 24.2 cents a litre on Wednesday, says the energy department.
Kenya's energy regulator had to raise its retail price of petrol and diesel due to a weaker local currency and rising global oil prices.
The retail price of all grades of petrol will increase by 41 cents per litre, says the department of energy.
Refiners in South Africa are seeking nearly 80 000 tonnes of diesel for delivery in January through spot tenders issued late last week.
A little too late to benefit most motorists returning from their end-of-year holidays, the price of petrol and diesel is to drop next week.
The retail price of all grades of petrol will rise by 45 cents a litre on Wednesday next week, the Department of Minerals and Energy said on Friday.