Many heeded the call and switched to solar panels, and now Eskom wants those generating their own power to pay for using the grid as a back-up.

South African Institute of International Relations (SAIIR) says customers can't be punished for complying with Eskom's pleas.

"I wouldn't be surprised if solar panels might become less attractive due to some punitive measures on tariffs or costs. Other measures might receive similar treatment from Eskom because the core of Eskom's argument here is that alternative energy sources are bad for the Eskom revenue stream", said SAIIR's Herman Pretorius.

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