Johannesburg - South Africa's national grid came within a hair's breadth of overloading last week, suggesting the region's top economy is going to battle to keep the lights on with the approach of the southern hemisphere winter.

State-run power utility Eskom said on Monday that demand last Thursday peaked at 32,081 MW and was met by a supply of only 32,103 MW - a gap of just 0.06 percent.

This means that an unexpected problem at a power station or a surge in demand on that day would have tripped the national grid.

Eskom said last month it was prepared to introduce rolling blackouts this winter in some parts of the grid to prevent a complete system collapse, which would inflict far greater damage on the economy.

Eskom, which provides 95 percent of the power to the world's top platinum producer, has been walking a tightrope for five years as it tries to bring long overdue new power plants online after the system was brought close to collapse in 2008.

Margins will be tight this winter though Eskom said capacity on Monday was seen at almost 35,000 MW against a peak demand forecast of around 32,700 MW. - Reuters