Does Eskom care about its customers?
Eskom should not be expected to shoulder the entire risk on its own, he told reporters in Johannesburg.
Maroga said while Eskom's long-term coal contracts - over 30 to 40 years - showed a measure of predictability, price volatility occurred in short-term contracts.
Eskom also wanted to pass on the risks of the fluctuating fuel price, especially the costs of the diesel it used to run on at least one plant.
Maroga's remarks came a day after the power utility began "pre-emptive" power cuts to cover shortfalls in the electricity supply.
He said on Wednesday the situation was being assessed every two weeks.
"When is the shortage going to end? I wish I could tell you it's going to end on... (a) particular date."
He said the more power consumers saved, the faster Eskom would be able to build its coal stockpile ahead of winter.
At present, Eskom had on average twelve days worth of coal in reserve. It aimed to increase this to twenty days before the start of the cold months, Maroga said. - Sapa