Power spikes due to load shedding should not cost you anything, says Eskom

Eskom has given assurance that large power users will not incur additional cost when they overshoot their notified maximum demand due to load shedding.

In response to questions, the utility said the “actual measured and chargeable demand will be reset to a value that would have prevailed had the event giving rise to the overshoot not taken place”.

Vally Padayachee, special advisor to the Association of Municipal Electricity Utilities, however cautions that this is not done automatically.

Power users must make sure that their bills are reviewed to avoid huge additional costs.

Those large power users not supplied directly by Eskom will have to engage their municipal distributor on the matter.

The issue relates to large power users – including residential complexes and other sectional title complexes – subjected to tariff structures that include notified maximum demand charges.

This is a charge to reserve certain agreed-upon capacity on the network for a client at all times. It is measured in kVA over a 30-minute period and the higher the capacity, the higher the charge. The client further incurs huge penalties when the agreed-upon capacity is exceeded.

According to Eric Bott, director at Energy Management Consultants, large power users take care to avoid power spikes to limit their maximum demand and thereby limit costs.

A factory for example will stagger the start-up of its machines and equipment, rather than start them up all at once in the morning when the first shift starts.

This is however not always possible when the power supply is restored after load shedding.

“The water in all the geysers in a residential complex will cool down during load shedding. When the power supply is restored, they all start up at the same time, which results in a power spike,” he says.

“In a residential complex with 200 units the maximum demand can increase from 330kVA to 578 kVA,” Bott says. At about R300/kVA it can cost the body corporate an extra R75 000, he says.

One complex he dealt with saw seven such peaks in one year, costing it R490 000.

Since different tariff structures that do not provide for demand charges at all apply to the owners of individual units, it is very difficult for the body corporate to recover such costs from them.

According to Eskom’s response, such charges to clients buying directly from the utility can be reversed in the following month.

“When a customer’s demand overshoot is caused by an Eskom electricity supply event, the actual measured and chargeable demand will be reset to a value that would have prevailed had the event giving rise to the overshoot not taken place,” it says.

“This is done within the month of the event or when it occurred. The customer will then pay only the demand-related charges for the demand that would have applied as if the event had not taken place.”

At municipal level this may however pose a challenge.

Municipal challenges

Bott says according to the applicable national standard, the power system must be stabilised after a supply disruption like load shedding and the maximum demand may only be measured over the second 30 minutes after supply has been restored. Most distributors however fail to observe that rule, to the detriment of the client.

Nevertheless, where geysers are concerned the 30 minutes of grace may not be enough. “It can take up to an hour before the geysers switch off again,” he says.

Bott advises body corporates to install software that enables them to stagger the start-up of geysers to avoid such peaks. The cost of doing so more or less equals the avoided cost over a period of about four months.

Rene Kilner, director of Trusted Utilities, confirms what Bott says. “It also happens at sites where you have different buildings,” she says.

One such site in Sandton saw its maximum demand, normally below 500kVA, increase to about 800kVA when operations in all the buildings resumed simultaneously after load shedding.

Kilner argues that the network needs up to two hours to stabilise before measuring the maximum demand.

She says the only way power users can determine how their maximum demand was measured and calculated, is to get the raw data from their distributor.

“You are entitled to it.

“They are supposed to keep the data for five years, although most municipalities only have it for about the last three years.”

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