A mini-grid project in suburban Melbourne is testing the possibilities of energy independence and consumers’ appetite for change, writes Alistair Parker.


Electricity network businesses have sometimes been overlooked as risk takers or innovators. The poles and wires that transport electricity to homes and businesses have not changed significantly in decades because they haven’t needed to. Customers have consistently used the electricity in a way we expected and we have consistently delivered it.

As that changes so does the way networks like AusNet Services are approaching how we expand, operate and maintain the electricity grid. Many residential and business customers have made the choice to install solar panels and batteries, and these technologies are allowing us to be more creative and innovative in how we use the electricity network for the benefit of all customers.

The AusNet mini-grid trial in Melbourne’s outer eastern suburb of Mooroolbark is helping us, and the industry, get ahead of this change. (AusNet is Victoria’s largest energy delivery service business, with $11 billion in electricity and gas transmission and distribution assets and more than 1.3 million customers.)

What’s the purpose of the trial?

Some have asked if the Mooroolbark Mini Grid is about supporting households go “off grid”, leading to networks becoming obsolete.

It’s not.

It’s about learning how renewable and community energy projects can be integrated into the network and how customers can directly and indirectly benefit from localised energy generation.

The trial is a snapshot of the future of the distribution network, with a high concentration of distributed energy in the form of battery storage and solar power in one street, and high levels of two-way electricity flows through a network usually set up for one-way electricity delivery.

At the centre of the trial are customers – supporting their choices and making sure the network can deliver reliable and safe electricity for everyone, regardless of whether they have solar panels or not. It’s also about supporting the delivery of new types of energy services and business models that are expected to evolve and grow on the back of changing customer needs and technology. By 2050, it is predicted that customer-owned sources of generation will supply 30-50% of Australia’s electricity needs.

But solar panels and batteries are still not affordable for everyone. Through our initial tests, we are already showing that not everyone will need this technology to benefit. We are exploring how the network copes with the high levels of solar power on an urban street without sacrificing power quality, and how mini-grid technology can improve customer reliability by providing power during network outages or major storm events.

We will also test whether mini-grids can reduce peak demand on the network, helping reduce the need to build expensive new power stations or network upgrades, thereby reducing costs to customers.

With many companies looking at getting the benefits of customer energy resources into the wholesale market and regulators investigating how to open up the value from customer-side resources, we will also test a future world where customers may be interacting with the wholesale market. These scenarios will take us beyond what our standard operating parameters are. They will push the limitations of the grid.

Finding the right community

One of our first challenges when setting up the trial was finding a test group – customers in an established community willing to allow us to test a range of scenarios in and around their homes for at least two years.

A scan of our 57, 000 electricity pole-top transformers gave us a list of potential locations. We needed a small-sized patch of network, with good smart meter coverage, average or high solar penetration, low level home vacancies and average demographics not far from Melbourne.

A street in Mooroolbark met our requirements. It provided a good mix of customer types – a mini snapshot of the AusNet Services customer base and a mix of enthusiasm levels, with some keen and engaged, some not wanting to take part and most sitting in between.

Each customer was provided with up to 3kW of solar panels with a Fronius inverter and the use of a 5kW Selectronic inverter and 10kWh LG Chem batteries during the trial. For those who already had solar panels, we provided additional panels up to a total of 4.5kW. Customers were also given access to a web-based portal that provides real-time information about the energy flow to and from the grid and through their homes, solar panels and batteries.

We appointed a dedicated customer engagement manager so participants had a consistent point-of-contact throughout the trial. Considerable effort was made to explain the project, renewables and electricity in one-on-one engagements during recruitment. Our focus throughout the trial has been to keep customers informed about what is happening, without being overly intrusive.

What makes our mini-grid different?

While mini-grids are being trialled across the world, what sets ours apart is that it’s in an established suburb and is being run entirely by renewable energy. It’s also fully interactive with the grid and has a high level of data capture and control capability

Our mini-grid is made up of 14 individual households that can generate, store and manage power, and be separated from the electricity network for periods. It operates using distributed renewable and stored energy in people’s homes. Typically, other mini-grids rely on a centralised diesel generator.

The high level of control capability, achieved via integrating the solar and battery inverters into a cloud-based control platform, means we can optimise power flows, depending on the needs of the network and who has excess energy and who doesn’t. AusNet Services has worked with local partners GreenSync and Power Technology Engineered Solutions during the trial.

Separating from the grid

Our first attempt to separate the home from the electricity grid and to form a mini-grid lasted just 10 minutes and involved eight of the homes, but it was a significant milestone. We recently achieved a separation of three hours, and expect to be able to extend this to a full day or even longer once the days lengthen and the clouds lift as we head into spring.

We used a combination of a central control platform and an inverter-based device known as a stabiliser, combined with the household solar panels and battery storage, to separate the mini-grid from the grid while maintaining a safe, secure and stable power supply. The homes, including two that had neither solar nor batteries, were able to maintain power by sharing electricity via AusNet Services powerlines.

The cloud-based mini-grid control system provided by GreenSync and the stabiliser took the mini-grid through a sequence of stages to test its stability as an independent, unified renewable energy system.

The stabiliser, developed by Power Technology Engineered Solutions, is a highly specialised smart battery storage system that smooths out short-term variations in energy supply and consumption across the mini-grid by either delivering or absorbing just the right amount of power, enabling the mini-grid to be 100% renewable rather than relying on a diesel generator.

What do our customers think of the trial?

While we have already gained an enormous insight into what mini-grids may deliver for the future, this trial has also allowed us to learn more about our customers. A recent survey of the participants found they had high-levels of satisfaction and trust in AusNet Services during the trial, but their interest in broader energy issues was not high.

What they all agreed on were the benefits of solar and battery storage, with most participants’ energy bills reduced significantly during the summer period.

The majority of our customers remain relatively passive electricity consumers and will either stay on standard retail arrangements, initiate some basic individual action such as installing solar power or take up new technology-based retail offers only when packaged by suppliers and marketed to customers as a simple proposition and choice.

But this is understandable. Families have more to do than think about what’s happening on the energy network. They expect us to do that. They just want affordable bills and to know that when they flick a switch, their lights go on.

Our responsibility is to deliver this, regardless of the changes underway across the sector.

What’s next?

The first year of the trial has already provided a valuable glimpse of how energy security and reliability may be boosted in the future and how large amounts of rooftop solar power generation can be managed.

During the next few months, we will develop additional control functionality to manage peak loads at the local network level as well as provide network support back up the network. We will also test the impacts of customers selling into the wholesale market at peak times and the impact of future local trading constructs.

We are also looking at how we can incorporate customer behaviour into the mix. So far, when homes have been taken off-grid, customers haven’t been aware of this until after the testing has been completed as we don’t want to see them change their behaviour. We have now invited them to participate in an experiment to see how long they can run off-grid by changing some of their behaviour.

Analysing customer behaviour may include introducing pricing incentives for customers to act a certain way or having them operate off-grid in a certain period. We would want to see how much they change their behaviour and what that new behaviour looks like.

It’s this innovation, risk taking and creative thinking that will allow us to test the boundaries of the grid and change the way our networks operate during the next decade.


Alistair Parker is executive general manager of regulated energy services at AusNet Services.