South Australia to trial “solar” hot water virtual power plant to act as midday sponge

A South Australia-based trial will aggregate more than 2,400 residential electric hot water systems to act as a virtual big battery, helping to soak up excess rooftop solar power in the form of low-cost electricity and providing a cheap and scalable form of demand management.

The $9.9 million trial, which is being backed by both the South Australian government and the federal government, via the Australian Renewable Energy Agency, will use the technology of Rheem Australia’s renewables brand, Solahart.

The project will integrate a Solahart Powerstore – which it describes as a solar smart, grid interactive, electric water heater – with a home energy management system across both solar and non-solar households, as well as across different socioeconomic groups.

Using a similar model to solar and battery-based virtual power plants, the Active Hot Water Control project households participating in the trial will be rewarded for such services as curbing electricity usage at peak times, participating in electricity price arbitrage, and providing network services to the grid.

As ARENA notes in its statement on the trial, hot water systems are significant users of energy, as well as being some of the most basic energy storage devices available, and therefore obvious candidates for much smarter use, both by households and network operators.

Mostly, electric hot water systems were timed to soak up excess coal power at night time. Now everyone realises it is a much better idea to have them times to soak up excess solar in the middle of the day.

Queensland has been doing this for a while, with a time-of-use tariff used specifically by distributors to power residential hot water systems during periods of low electricity demand. This period of low demand has traditionally been the night time, but has lately shifted to the middle of the day, when abundant solar generation pushes prices right down.

In South Australia, where booming rooftop solar uptake could see the state become the first gigawatt-scale grid in the world where consumer-generated solar electricity effectively eliminates grid demand, it is well past time that solutions like this were brought into play.

“As more of Australia’s electricity comes from solar, we need to increasingly shift more of our energy consumption to daylight hours when solar PV is generating, rather than at night when solar isn’t available,” said Darren Miller, the CEO of ARENA, which put $1.98 million towards the trial – an amount matched by the SA government.

“This trial will help to create a pathway to scale up the use of hot water systems in demand management, while rewarding customers for taking part in the trial through cheaper energy bills,” Miller said.

Federal minister for energy and emissions reduction, Angus Taylor, said the project would help manage Australia’s world-leading uptake of rooftop solar.
 
“Solar power can only be used when the sun is shining, which is why we need to find more ways to use it when it’s available to stop it going to waste,” Taylor said.

“This project will help South Australia to get the most out of this boom and maximise the use of renewables in the grid, reducing pressure on the electricity system.”

Rheem CEO Chris Taylor welcomed the support for the trial, which is expected to create a number of additional jobs at Rheem Australia, while also indirectly supporting local jobs in installation.

“We are thrilled with this initiative and collaboration,” Rheem’s Taylor said. “South Australians are leaders in the adoption and use of renewable energy solutions, and uniquely, this partnership and technology aims to make it easier for SA residents to further reduce their energy bills, enabling participation in the renewables boom whether or not they are able to invest in solar PV.”