Eskom had a debt of R333-billion at the end of last year, according to a written parliamentary reply by Public Enterprises Minister Lynne Brown.
The power utility's approved borrowing programmes in the 2015/16 corporate plan was R237-billion.
"Consequently it is envisaged that the Eskom debt will exceed R350-billion over the next five years," Brown wrote.
The corporate plan made provision for the power utility to continue with the Medupi, Kusile and Ingula build programme that would add over 9 600 MW to the grid.
Eskom would be able to carry on providing almost all the country's electricity requirements through the acquisition of additional coal-fired stations.
"The future nuclear build programme will be dependent on an appropriate funding model being developed by Eskom and government," she said in response to the questions by DA MP Malcolm Figg.
On March 1, 2016, the National Electricity Regulator of South Africa said it had approved an average 9.4% electricity price increase for Eskom for the 2016/17 financial year.
It said no to Eskom's request for a higher tariff increase to make up for unbudgeted costs of diesel during the 2013/14 financial year, saying this had happened because of poor maintenance.
Eskom CEO Brian Molefe hinted that this attitude by Nersa might influence Eskom's approach to keeping all the lights on if the grid started taking strain.
Nersa announced it would not grant Eskom the R22.8-billion variance it requested for the costs incurred in the production of electricity in the 2013/14 financial year. It has instead approved R11.2-billion, which amounted to a 9.4% tariff hike for the 2016/17 financial year.