Eskom has confirmed it terminated electricity supply due to non-payment following the surprise temporary suspension of the entire rail service in the Western Cape on Thursday afternoon.
"We have engaged the customer [Prasa] over a lengthy period of time trying to get them to settle their account and today we terminated supply," Eskom spokesperson Sikonathi Mantshantsha told News24.
"However, at this point, we have received a proof of payment which brings Prasa's account to current."
Mantshantsha said they had now started the reconnection process, which would take effect within hours.
However, it was possible that some sites might only regain power by tomorrow.
Hundreds of thousands of commuters in the Western Cape were stranded on Thursday afternoon.
At Cape Town station, people were seen joining extremely long queues for a minibus taxi back home.
There were also long queues for buses.
Passenger Rail Agency of South Africa (Prasa) spokesperson Makhosini Mgitywa earlier said that Eskom disconnected power to Metrorail because payment was 34 days overdue.
"Prasa was not aware of Eskom's action as the rail agency was in constant contact with the power utility regarding the account. Eskom wants Prasa to pay within 14 days of receiving an invoice, which is currently practically impossible. This point has been raised with Eskom, and Prasa will reiterate it as we engage them further.
"We also wish to assure affected commuters and other stakeholders that, while Prasa is facing a cash-flow crunch, it is however not bankrupt," said Mgitywa.
Prasa said it was processing the payment and was optimistic that power would be restored soon.
The DA-run City of Cape Town has been fighting to take over management of the rail service.
The party's provincial transport and public works spokesperson, Daylin Mitchell, again called on national government to devolve rail to sub-national governments.
"What happened today to the commuters of the Western Cape is an absolute disgrace. It is completely unfair that passengers were left with no trains because Prasa didn't pay its Eskom electricity bill," said Mitchell.
"Prasa has essentially pulled the plug on train services – the very mandate for which it exists."
Transport Minister Fikile Mbalula is expected to brief media on the situation on Thursday evening.