Biggest battery storage systems in South Africa

The biggest battery energy storage system (BESS) in South Africa boasts 1,140 megawatt-hours (MWh) of storage capacity, enough to supply the average demand of 76,000 South African homes for 12 hours.

As the adoption of renewable generation like solar and wind expands over the coming years, commercial and utility-scale battery installations will play an increasingly important role in energy management.

Solar and wind farms are much more environmentally friendly power producers than coal or gas-based generators but have fluctuating performance depending on weather conditions.

Solar power depends on irradiance, with thick cloud cover reducing its output substantially. It also cannot provide any meaningful contribution when the sun is down.

While wind farms can provide a lot of energy at night, their production can still vary greatly from one day to the next.

A BESS aims to address this by storing excess energy generated during peak generation periods for dispatch when required. It can also be used to shave peak demand on other power sources.

In utility-scale applications, multiple BESS units are combined in installations that consists of thousands and even millions of battery modules with powerful inverters and advanced software.

Well-known BESS units include the Tesla Megapack, which can store around 3.9MWh of energy.

However, there are also several South African BESS manufacturers.

Edenvale-based Freedom Won offers the MegaTower with up close to 1.5MWh capacity. Multiple MegaTowers can be combined in a purpose-built container to hold 5.9MWh of storage.

SolarMD also offers a 1.5MWh container-based BESS, while Blue Nova Energy’s iESS system features up to 3MWh capacity in a single container.

The biggest deployed BESS by far is at Scatec ASA’s Kenhardt hybrid and solar battery facility in the Northern Cape, which became fully operational in December 2023.

The BESS is manufactured by the Chinese giant BYD, which has recently become more well-known for its electric vehicles and has been making batteries since the late 1990s.

The BYD T28 BESS system at Kenhardt consists of 456 2.5MWh units built into container-sized enclosures weighing 30 tonnes each.

Its inverter system can support a peak output of up to 225MW at any given time.

That is roughly a quarter of the capacity of one of Kusile or Medupi’s modern coal-fired units but more than the older units at stations like Camden, Grootvlei, and the now-decommissioned Komati plant.

According to Scatec, the BESS can continuously supply 150MW of power from 05:00 in the morning until 21:30 in the evening, which includes the peak demand periods during which solar output is low or non-existent.

The facility is fed by three solar farms with a combined peak generation of 540MW, sufficient to charge the entire BESS in about two to three hours.

Kenhardt is one of several renewable IPP projects feeding power into the national grid through power-purchasing agreements with the national government.

Eskom’s BESS sites

The second-largest BESS currently in operation is an Eskom facility at Pongola in KwaZulu-Natal with a 160MWh capacity.

This facility was commissioned in December 2023, a month after Eskom installed its first BESS at the Hex site near Worcester in the Western Cape, boasting 100MWh of capacity.

The Hex installation was also the third-biggest BESS in South Africa at the time of publication.

The two facilities form part of Eskom’s greater Just Energy Transition (JET) BESS project, which had aimed to deploy a distributed network of 1,440MWh energy storage across 12 sites by the end of 2024.

However, the JET project has run into funding problems and as of October 2024, just 13% of this capacity had been commissioned.

A further 75MWh of capacity at Graafwater and Paleisheuwel was due to finish construction by November 2024.

Eskom’s largest BESS under the JET project is currently under construction at Skaapvlei in the Western Cape, which was slated for completion by the end of January 2025.

However, with a peak output of 80MW and 320MWh of storage, it will still be substantially smaller than the Kenhardt facility.

The table below compares the five biggest BESS installations operating or expected to be operating in South Africa by January 2025.