Solar panels shine in smart grid management

Australia’s electricity networks are facing a wicked problem – how to stabilise systems built for a bygone era, when power was produced centrally and distributed far and wide. With rooftop solar uptake continuing apace, electricity network operators have become increasingly concerned that having more than 2 million properties injecting power into the system – often outside peak usage times – is driving voltage variability and dragging down network performance.

“The network is often now working in the opposite direction to how it was originally designed to work, [which was] to pump generally coal-fired power from a big coal-fired power station all the way to its tips,” says Dani Alexander, a Research Principal at the Institute for Sustainable Futures (ISF).

A 2019 International Energy Agency report, the National Survey Report of PV Power Applications, noted that with 16.3 gigawatts of installed photovoltaic (PV) power – or 600 watts per person – at the end of 2019, Australia led the world in solar per capita. More than a third of households in South Australia and Queensland have rooftop installations. In some neighbourhoods, every second home boasts solar.

However, Australia’s domination of rooftop PV – with more than 2.3 million installations and rising – sets it apart from most other countries. And the power generated is widening the ‘voltage envelope’, sparking networks to seek solutions.

It's flipping the problem on its head… suddenly it becomes a solution.

— Dani Alexander, Institute for Sustainable Futures

At the face of it, the answer seems relatively straightforward and, thanks to Alexander and her colleagues at ISF, is already proven: simply harness customer-owned panels. When needed, set the network to send messages to solar and battery systems through smart inverters telling them to pump in either active power from panels or batteries, or some of the ‘reactive’ (latent) power stored in inverters.

“It's flipping the problem on its head… suddenly it becomes a solution. It’s very exciting,” says Alexander.

A proven solution

Utilising customer-owned installations was proven to work by Alexander and her colleagues at ISF in an award-winning three-year study that clearly demonstrated solar PV and batteries can be a valuable resource for the businesses that manage electricity networks. The Networks Renewed study successfully tested a viable commercial approach to smart inverter control, in particular for voltage regulation.

The $4.8 million project received $1.59 million in funding from the Australian Renewable Energy Agency (ARENA). It ran over two phases: a pilot-scale demonstration (2017-18) to test the technical voltage control capability at a small scale, followed by a market-scale demonstration to ramp up deployment and deliver significant network impact (2018-19).

It wasn’t about disruption, Alexander says, but about “changing the landscape in a way that is a win, win, win”.

“We brought together the network businesses who manage the poles and wires and we worked with inverter companies to make sure we had the right types of inverters that could do the job.”

We know already that it’s making a difference… It’s a win-win situation for all involved.

— Sharon Naldrett, Yackandandah resident

Alexander’s team recruited 90 customers to trial innovative commercial models with Essential Energy at Bellingen in NSW and AusNet Services near Yackandandah in Victoria. Two new energy businesses, Reposit Power and Mondo, provided the control and integration technology.

Essential was interested in ‘real power’ impacts – activating customer-owned batteries to pump power into the grid to support voltage variability. AusNet wanted to explore a different solution – drawing on the latent or ‘reactive power’ that sits in solar inverters and is essentially free energy.

Victorian resident Sharon Naldrett wanted to be involved at the beginning of something that might change how Australia distributes energy around the nation – and even around the world. Sharon’s family of four have a 5kW solar system and a 10kW battery on their home.

“We are on a SWER line, which is a single-phase electricity line,” she says. About 140 households are connected to the same line and when Sharon’s parents built their home 30 years ago they were told they were the last to be added because the drain on the grid was maxed out.

“But the houses didn’t stop getting built,” she says. Planned outages have to happen eight to 10 times a year, and when they occur, the nearby primary school needs to close.

Being part of the trial has allowed Sharon and her neighbours to enjoy a less volatile system and they are experiencing fewer power outages. “We know already that it’s making a difference,” she says. “We have power we can feed to our neighbours in times of need and we can take power from them. It’s a win-win situation for all involved.”

Going mainstream

“This trial proved you can use inverter-based resources like solar and batteries to regulate network voltage, which is one of the key issues with higher levels of solar uptake,” says Alexander. “You can actually solve the problem at the source. And you could bolster the grid to make it more reliable through access to all of these inverter-based resources.”

If you're providing a service then you get reimbursed for that. You're not then wasting renewable power, cutting it off from the system.

— Dani Alexander, Institute for Sustainable Futures

The wicked problem is how to create a mainstream solution – and that is a challenge that Alexander’s team believes they can solve.

“We’re proposing a service-based solution rather than a constraints-based or a limits-based solution,” says Alexander. “…instead of saying: ‘OK, that’s enough solar everybody – we're going to ramp your system down and you're not going to be generating that much power’, we're saying: ‘OK everybody, we're experiencing a voltage issue – we're now going to ask you to provide this service and we’ll pay you for that service.’

From the customer's perspective that will be much more palatable, and likely to be more equitable. As Alexander explains, “If you're providing a service then you get reimbursed for that. You're not then wasting renewable power, cutting it off from the system.”

But how do you design a model for a system that Alexander describes as being like many hands where the substations are the palms?

“If you think about your hand, the network can only see the palm of the hand. It can't see the tips of our fingernails. The issue is then how do you know when you're actually experiencing voltage issues?”

In the past it has been through customer complaints – someone calling up to complain of flickering lights when there is under-voltage or seeking a new toaster after over-voltage ‘popped’ theirs.

Mainstreaming the solution won’t be straightforward – but it’s not impossible either, says Alexander. “There's actually a whole lifecycle that needs to happen from understanding the problem to solving the problem to feeding back to the network the information that the problem is solved. That’s an eight-step process – and those eight steps, they don't currently exist,” she says.

Going mainstream requires progressing the business model or the market framework “in all of those eight steps”, says Alexander. “And that's the complexity, which is difficult to communicate to a customer.”

Alexander estimates Australia could be two to five years away from a mainstream solution.

“It's important to tread carefully when we're talking about the electricity system because it needs to be managed carefully,” she says. Nevertheless, she hopes there will be collective will to find a win-win path forward. “Things can happen in a very short period of time if people think it's a good idea,” she says.

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