In the midst of escalating cold weather pressures on regional grids, Eskom, South Africa’s power utility, has issued an urgent plea to its customers. If you have a backup power system, the company advises, keep it offline for at least an hour following load shedding to prevent potential circuit trips.
The “Cold Load Restoration” Issue
Eskom sounded the alarm on Friday, 21st July, alerting that customers might face extended durations of power outage due to a phenomenon known as “cold load restoration”. This issue arises from higher evening peak demands, caused by extremely cold weather in certain areas of the country, as well as the cumulative effect of illegal connections in some regions.
Certain areas of the Western Cape, specifically Blackheath, Bluedowns, Delft, Silversands and Khayaletshia, have been identified as particularly susceptible.
Eskom’s Practical Guidelines
In the face of this crisis, Eskom has provided some practical advice for its customers. To alleviate the burden on the grid, stoves, geysers and pool pumps should be turned off, only to be re-engaged half an hour after power restoration.
Equally important, backup power solutions like inverters, UPSs and others should be disconnected from the main supply during load shedding, and only reconnected an hour after the outages have concluded.
A Broader Grid Stabilisation Strategy
While this alert is specifically targeted at the problem in select areas, it forms part of Eskom’s larger strategy to alleviate grid overload following load shedding. During a system status presentation in May, Eskom implored South Africans to delay charging their inverter systems post-load shedding to lessen the demand on the grid.
The delay in charging inverters is one of the many demand-side energy reduction strategies proposed by the utility, alongside powering down unneeded electronics, preventing “izinyoka” (cable theft), and ensuring electricity fees are paid promptly.
The Role of Inverters
Eskom warns that charging inverters during peak times could spike the demand by as much as 1,400MW, equivalent to an entire stage of load shedding.
The company suggests, “If possible, set the inverters to charge batteries during the night, when the demand is at its lowest. Also, where solar panels are used, charge batteries 10h00 to 14h00, when the maximum output is achieved from the panels.”
Inverters are critical during rolling blackouts, supplying electricity to power garage doors, keep a few lights on or maintain wifi connectivity for work, among other uses. They switch on automatically during power outages, providing uninterrupted electricity. However, in more severe stages of load shedding, they may drain completely, and recharging could take longer than usual.
Grid instability in certain parts of the country may lead to post-load-shedding outages due to the surge in demand when power is restored.