How rooftop solar is changing South Africa’s energy landscape

The explosive growth of rooftop solar-generated electricity has dramatically reduced demand on Eskom – although the utility still threw the country into Stage 5 yesterday because of continuing breakdowns.

However, alternative energy migration also means much less revenue for Eskom.

According to electricity supply analyst Anton Eberhard, Eskom’s own estimate was that installed rooftop solar power has rocketed from 983 MW in March last year to 4.4 GW at the end of last month – a nine-fold increase.

That 4,.4 GW is also about 10% of Eskom ‘s total gird capacity.

It is also the equivalent of four stages of load shedding, at 1 GW each.

Eberhard noted that the solar power “ could reduce the residual load that Eskom has to meet during the day, meaning less load shedding and more available energy to restore its pumped hydro and diesel storage.”

The power utility yesterday announced that it was ramping up load shedding to stage 5 from 2pm.

“Due to further delays in returning generating units to service, as well as the further failure of 5 generating units today, Stage 5 load shedding will be implemented from 2pm today until 5am on Tuesday,” Eskom Crisis Communication Manager Menzi Mngomezulu said.

Mngomezulu said thereafter, Stage 4 load shedding would be implemented until further notice.

The power utility has been battling with generation capacity in the last few weeks amid the series of cold fronts that have swept across the country, which has accelerated the need to migrate from the grid for many South Africans.

Energy analyst Lungile Mashele said while migration or even installed capacity could certainly help reduce load shedding it also had other effects on the grid.

“It increases the ‘duck curve’ which is the difference in contracted demand and residual demand (demand less renewables),” she noted.

“This duck curve means the grid operator requires additional spinning reserve to track renewables during the day but more importantly ramping capacity prior to the evening peak.”

“Yes solar PV is invaluable especially during the day. With the addition of battery it would play a pivotal role during the evening peak.”

She also said with more variable renewables entering the grid there was a need for increased grid flexibility.

“The grid needs to ramp up between 3-5GW every evening to meet the evening peak. This is currently a huge challenge for the system operator,” she added.

However, Independent economic and energy analyst Tshepo Kgadima said intermittent power was not an on-grid solution, but an off-grid solution, and would be a disaster for the grid.

He said in the last financial year Eskom went from selling 193 terawatt-hours to 160 terawatt-hours which led to a loss of over R70 billion and anything less than that for the next financial year will leave the power utility bankrupt.

He also noted the increasing tariffs and rolling blackouts were accelerating the migration, “however, whether there is load shedding or not people would still have to use those batteries and draw power from the batteries which they have charged during the day using solar”.

“So therefore, it means demand for Eskom will continue to go lower and lower, and Eskom will lose revenue of close to R80 billion,” he added.

“Secondly, the tariffs, the equilibrium have been breached, and what do I mean? It now costs less to go off grid as a household than to stay on, the tariff is R2.18 as approved by the National Energy Regulator of South Africa (Nersa).”

He said even municipalities had a higher tariff, “but now you can generate, and go off grid for less than R1,60 a kilowatt-hour”.

“So no one in their right mind will continue to draw power from Eskom, because once they have installed a lesser solution, it then means that there are revenue losses that the power utility will incur.”