By: Martin Fernandes - Business Development Manager (Africa), Operational Technology at Fortinet

As we celebrate the International Day of Clean Energy, South Africa’s energy grid stands at the cusp of a historic transformation. Distributed renewable generation at massive scale is both a victory for sustainability and cutting-edge modernisation. But this bright future and series of successes also represent an equally, if not more, important transformation of the nature of vulnerability. 

The rigid, "old" grid was a fortress – centralised, isolated, and physically segmented. The new, "green" grid is a web – decentralised, distributed, and hyper-connected – for good reason. This new model of energy generation, though, is exponentially more vulnerable to cyber-attack, and we must secure it now, not after the first major incident.

From a fortress to a web

The risk landscape for our national grid has fundamentally changed. In the past, the primary cyber-risk was to a handful of large, state-owned power stations, where operational technology (OT) networks were isolated from the corporate IT world.

Today, our grid is being connected to thousands of new, privately-owned endpoints. Every wind farm, solar installation, battery storage facility, and municipal smart meter is a new, directly (or indirectly) internet-connected device on the network. Each one of these connections is a doorway.

The vulnerability does not lie with the national grid operator alone, but with the varied security postures of every new IPP. A small-scale solar farm connecting to a municipal grid with an insecure, unpatched SCADA controller or a default admin password creates a backdoor that could allow an attacker to pivot from that private facility into the public grid. This is the new, distributed reality of our infrastructure risk.

And the scale of the expansion of this transformation is huge. The government’s IRP 2025 indicates that total installed capacity of renewables – in the form of wind and solar PV – will increase from about 12 000 MW currently to about 75 000 MW by 2039, representing more than half of the 105 000 MW of new generation to be added by that date.

For the period up to 2042, the plan indicates that about 5 000 MW of new renewables generation should be built yearly.

The threat of data, not just downtime

The most sophisticated threat to a smart grid is not just "shutting it down”. It is "making it lie”.

A modern, green grid relies on thousands of data points being fed to the central operator every second – how much power is a wind farm producing? What is the current demand from a specific suburb? This data is used to automatically balance the load across the entire network.

A sophisticated attacker could compromise a series of solar farm controllers and, instead of causing a blackout, simply feed false data to the grid operator. Hypothetically, if the central system is tricked into believing it has more (or less) power than it actually does, it could trigger automated load-balancing decisions that result in cascading and widespread failures. In this scenario, the attack isn’t a case of merely creating an outage; it is the targeted manipulation of the grid's nervous system.

This risk is amplified by the third-party supply chain. Many smart meters and solar inverters are manufactured by a few large providers. A single vulnerability discovered in one of these common devices – a "zero-day" exploit – could instantly create a weapon that attackers could use to target many homes and businesses simultaneously.

It has to be noted that the cybersecurity management of South Africa’s energy grid has been exemplary for a long time. As the grid itself changes, though, the way it is secured needs to as well.

Securing the public-private energy grid

This new, decentralised energy model is, in effect, one of the largest Public-Private Partnerships (PPPs) in the country's history. As such, it requires a new, unified model of security – one that I have touched on recently in the context of Sovereign SASE.

The national grid operator can’t be the only one responsible for security – especially not now. There must be a shared security framework that every private IPP must adhere to before they connect. This is a non-negotiable part of building a resilient system.

First, this requires Zero Trust at the point of connection. No device – whether a wind turbine or a municipal meter – can be trusted by default. Each must be authenticated and authorised before it can communicate with the wider grid.

Second, network segmentation is critical. The control systems for a private solar farm must be digitally isolated from its own corporate IT network. A phishing email that compromises the front office should have no possible pathway to the OT systems that connect to the national grid.

As we celebrate the progress in our energy sector, we must be clear-eyed about the new responsibilities that come with it. The green transition is also a digital transition. Securing this new, distributed, and vital infrastructure is the foundational task that will determine whether our new energy model is truly sustainable.