There’s a better option than simply switching off South Africa’s geysers



To reduce the strain on the national grid during peak hours, regulators are considering cutting off power to household geysers. But there are far better options than this heavy-handed approach to demand management, which would bring a range of unintended consequences.

Among the technologies being piloted are systems that allow authorities to control your home’s electricity usage. Those include ripple relay systems and geyser switches – which are used to halt the supply of power to geysers – and load-limiting smart meters, which suppress electricity supply to households. 

There are several downsides to this strategy, including that it leads to sudden spikes in demand when geysers are turned back on – unless geysers are brought back online in a staggered approach, though that would prolong power cuts. Further, in a typical family home, roughly 15% of showers will be cold in the winter months if we go this route.

A recently concluded 30-month study in the Western Cape has unequivocally proven that there is a better, less disruptive way forward.

Under the pilot study, 500 electric geysers in Cape Town and the Hessequa Local Municipality were equipped with artificial intelligence-enabled devices developed by Plentify.

In collaboration with the two municipalities as well as German development agency GIZ, clean energy financing facility EEP Africa, and others, we found that the devices reduced each geyser’s peak-period energy use by up to 80% – without compromising on hot water availability.  

The devices, called HotBots, shifted each geyser’s energy use away from peak hours while still ensuring that residents had hot water when they needed it. In doing so, we reduced peak load by up to 430 watts per geyser, on average.

Aggregated together, a fleet of HotBots can make a big dent in the nation’s energy crisis. Here’s how:

First, the HotBots shifted a significant share of their usual morning peak energy use into the afternoon. That meant water was heated up when there was less strain on the grid, but closer to the time when hot water is actually needed for evening showers and other activities.

Similarly, evening peak energy demand was shifted to the early morning, when most people are still asleep and power consumption is low. 

In each case, energy use was only shifted to the extent that it did not threaten the supply of hot water.

The result was a four-fifths reduction in peak energy consumption, and uninterrupted hot showers.

In a city like Cape Town, installing these devices in just a quarter of households could cut rolling blackouts in the mornings and evenings by a cumulative 20 hours every month, according to the study’s findings, which were independently verified by the University of Cape Town.

The devices also improved each geyser’s overall energy efficiency by up to 24% by switching them off when they did not need to be consuming electricity. Further, by coordinating the devices in such a way that each geyser drew power at a slightly different time, maximum demand at any point in time across the entire fleet was slashed by up to 60%. 

This, we believe, is far superior to the alternatives that are being tested in parts of the country. And this solution has been further refined since the early days of the study, meaning that the energy savings are now even more substantial. 

Rather than locking in sub-optimal solutions for years or even decades, South Africa has an opportunity to emerge from its electricity crisis with a far more resilient and sustainable energy system in place – one that benefits both the grid operator and ordinary households.

To get there, we must prioritise a broad range of interventions now, including programmes that encourage the use of energy efficient lighting and appliances, a move towards time-of-use tariffs, and the adoption of technologies such as smart geyser management devices.

The study illustrated that we can see a meaningful reduction in peak electricity demand, a smoother load profile, lower household energy bills, and a constant supply of hot water all at the same time, even in large households. 

Bringing this to fruition will require collaboration between government, municipalities, Eskom, businesses, and households. In our view, Project Smart Geyser has proven what is possible, and it is time to scale up our collective efforts.

Want to do your part in reducing strain on the grid?

Join the Plentify revolution by getting your very own HotBot.