Vincent Xaba is not a happy man.
As a restaurant manager in Johannesburg, he's had to throw away more than $500 worth of food, which was spoilt because of rolling electricity blackouts.
(SOUNDBITE) (English) MANAGER AT TSA AFRICAN RESTAURANT, VINCENT XABA, SAYING: "We bought a generator, but it's not up to standard electricity.
It is the real commodity, which we are supposed to use.
So, now we don't know when is this going to end.
So, I am losing a lot of money, I am losing a lot of customers because of electricity.
Our meat is getting spoiled, our drinks are getting warm.
Everything is just in a big mess." Eskom - which supplies over 90 percent of South Africa's power - is struggling with capacity shortages.
Following faults at its coal-fired power stations, low water levels at hydroelectric plants, and diesel shortages.
It's also lost electricity imports from neighboring Mozambique after a powerful cyclone - which has ravaged parts of Zimbabwe and Malawi too.
On Tuesday, Public Enterprises Minister Pravin Gordhan said he could not give a date for when power cuts will end.
For small and medium-sized business owners, frustration is mounting.
(SOUNDBITE) (English) OWNER OF AUTHENTIC SNEAKERS CLINIC, TUMELO, SAYING; "Without electricity it's going to be hardship, it's going to be hard.
So, going forward, I don't know what we can actually do.
It's actually killing us.
It really frustrates me a lot." Eskom's power station performance has deteriorated steeply because of delays to critical maintenance work on ageing power plants.
And long-term neglect means there are no quick fixes.
The crisis presents a threat to President Cyril Ramaphosa's efforts to boost investments and economic growth.
And it's likely to be a hot topic for voters ahead of a general election in May.
The rolling blackouts - known locally as 'loadshedding' - started last Thursday.
Up to 4,000 megawatts is being cut from the grid on a rotational basis.