Eskom explains why town with own solar power cannot reduce load-shedding
Eskom says that Free State town Frankfort cannot exempt itself from national load-shedding schedules as its privately-supplied solar power was insufficient to meet its total demand.
The utility welcomed a recent court ruling dismissing private power distributor Rural Maintenance’s application to continue implementing its own load-shedding schedule in the town while a dispute over the practice was before the National Energy Regulator of South Africa (Nersa).
Rural Maintenance is contracted by the Mafube municipality to distribute electricity to Frankfort, which it buys from four private solar farms with a maximum combined capacity of 3.7 MW.
The company has claimed that these plants sometimes had higher generation than the town’s demand at peak output during the day, allowing it to exempt homes and businesses from load-shedding for a limited time.
But Eskom said that Frankfort’s solar plants did not have sufficient generation capacity to cover all the town’s electricity needs during load-shedding.
“Even during daytime hours when the plant is running at optimal operation, a portion of the town’s electricity requirements are still supplied by Eskom,” the utility said.
“As in the rest of the country, the Eskom-supplied electricity to Frankfort is also subject to load-shedding.”
Eskom said that Rural Maintenance was required to abide by regulation NRS048-09 of the Nersa-approved National Code of Practice for Emergency Demand Reduction and System Restoration Practices.
That ensures the fair implementation of load-shedding to protect the integrity of the national electricity grid.
“We are, therefore, relieved that the application brought against Eskom by Rural Maintenance, the electricity distributor for Mafube Local Municipality in the Free State, its subsidiary (Rural Free State) and the Mafube Business Forum, has been dismissed with costs by the Johannesburg High Court on 20 April 2023.”
Baseload versus standby capacity
The utility explained that it had approved an application by Rural Maintenance to implement “self-load-shedding” on 25 January 2023.
This practice only allows a qualifying municipality to protect its critical loads, such as sewerage systems and water pumps, from interruptions.
“Where a municipality or metropolitan municipality has embedded generation, and such generation is not already included in the normal load profile of the municipality, such generation may be used to reduce the load reduction required under emergencies,” a clause in NRS048-09 states.
“In the case of Frankfort, the generation is already included as part of the normal load profile, and as such, the generation cannot be offset against load-shedding,” Eskom stated.
“The PV plant in Frankfort has no standby capability to offset the total demand; thus, the plant’s output forms part of the system base load and Frankfort remains subjected to load-shedding.”
The distributor started implementing self-load-shedding on 01 February 2023.
However, Eskom took issue when Rural Maintenance also started implementing a self-created practice called “voiding”, where they did not implement any load-shedding as per the approved schedules when their solar PV plant was in optimal operation.
“Eskom repeatedly rejected this proposal and attempted to help Rural Maintenance Free State understand why this is unacceptable and in violation of NRS048-09,” Eskom said.
“It is at this stage that Rural Maintenance opted to institute legal processes against Eskom.”
Eskom attempted to illustrate why the voiding practice was problematic by using a metaphor of Frankfort as a household with a grid-tied rooftop solar installation without battery capacity.
“Although the installation [solar plant] contributes to a reduction in the need for utility-supplied electricity to the household [Frankfort], its generation capacity is not sufficient to cover the total electricity demand of the household,” Eskom said.
“When utility-supplied electricity is interrupted during daytime hours while the solar installation is in optimal operation, the solar system is still able to fulfil some of the household’s energy needs.
“During load-shedding, the family [town] can still switch on lights and some appliances, but they will be limited by the supply from their solar system [solar plant].
“If this household [town] had battery storage for their solar system or if they had an additional power source that is sufficient for their demand, they would have been better equipped to continue with life as normal during a power interruption such as load-shedding.”
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