Australia leads the world on rooftop solar: We must now lead on making it smart

Every electricity grid is special, unique in the challenges it faces and opportunities it is offered.

This does not mean the global community cannot learn from each other, since there are elements that are often similar, like the way the network or market is structured. What it does mean is that each country has a chance to make a specific contribution to the global transition if its leaders can identify and leverage that country’s areas of strength.

In Australia, we are leading the world in the deployment of rooftop solar on an electricity grid that is long, connecting a dispersed population, and without any major neighbouring country with which to share power.

In addition, these inverter-connected generators act very differently to fossil-fuel generators that have their spinning turbines directly connected to the grid.

This is an exciting opportunity for the world to see how an inverter-driven approach can drive an energy transition.

Though, if you were a “glass half empty” character who preferred centralised generation and fossil-based analogies, you might call us the canary in the coal mine. The truth in that analogy is that if we do not get it right, and do not ramp up research efforts in this area, it could be disastrous.

As Professor John Fletcher, Director of the UNSW Digital Grid Futures Institute, explains, we are approaching a situation where 40% of total power generated will be from inverter-based generators.

“This scale of inverter penetration is globally untested,” Fletcher says.

“While similar designs are in place and effective in isolated or microgrid situations, the ability of inverters to sustain load over the geographical characteristics of Australia’s grids (both east and west) is unclear, particularly in the case of anomalous or fault conditions.”

In other words, multiplying inverter-based connections to our grid, exponentially multiplies the complexity of managing our grid. Not only is it the multiplicity of inverters delivering active and reactive power, but also the speed of the inverters’ response to the changes in the conditions at the point of coupling to the grid.

The combined capacity of our rooftop solar systems is now officially our largest generator in the National Electricity Market. But our market operator cannot even “see” it.

That is, our hardworking energy market controllers (not dissimilar to air traffic controllers) are constantly working with (or against) an invisible force of generation that can boom and bust from a passing cloud.

The question is, in the future will we be flying blind?

We are definitely breaking new ground. And to manage the millions of small, variable generators that will be connected to the grid we will need a different approach.

The Australian Energy Market Operator (AEMO) has put forward high-level scenarios in its Integrated System Plan or “ISP” but it only provides a scaffold for what we need to understand. We now need a concrete, detailed, granular set of tactics to execute this plan.

Some of this work is underway through CSIRO’s contributions to the Global Power System Transformation Consortium (G-PST), which is seeking to solve the first “physical layer” of technical integration.

However, there are still many topics to investigate, for example power system protection for the cascading actions of millions of devices generating energy or the fact that our grids will be exposed to more and more extreme weather events.

Given resourcing constraints, the G-PST is not yet able to investigate how the market might evolve, the global economic environment, and other drag factors or tail winds that might hinder or help the transition.

If we don’t answer these critical technical questions, the grid could fail. Clearly this is not acceptable. And, answering these technical questions is also critical to accurately determine the cost of the future system.

Much has been made recently about the comparisons between different approaches to costing the energy transition. In particular, whether we are fully costing the non-generation costs in CSIRO’s “GenCost” model and AEMO’s ISP.

As Andrew Richards, the CEO of the Energy Users Association of Australia, calls out, we need to “make sure we are having an honest conversation about the total system cost of getting to net zero.”

Many of the costs in question are associated with building the electricity network (both transmission and distribution), firming variable generation with storage or dispatchable generators, and providing system services like inertia that are currently provided by those physically spinning fossil-fuel generators.

Some have argued that all of this will be much more expensive than a system powered with coal, gas or nuclear. CSIRO and AEMO have both issued clear public statements that this is not the case and that their cost estimates include all the extra bells and whistles we need to invest in to support variable renewables.

CSIRO’s chief energy economist Paul Graham goes as far as to say, “When we make these calculations, we find that the LCOE (levelized cost of energy) of moving to the variable renewable shares of between 60-90% is lower than the LCOE of any other technology.”

But the question that has been rightly raised is that we cannot fully understand the cost of this future system because we do not yet know all the technical elements of a system that is powered by such high penetrations of variable, and inverter-based generators.

We need to get to the bottom of this. We are at the point where we must get into the nitty gritty detail. The nature of this new frontier demands an accelerated research effort to address the likely challenges Australia’s electricity grids will face in the future.

John Fletcher’s team, along with the UNSW Real-time Simulation Laboratory, has made a good start through an ARENA-funded project with AEMO, TasNetworks and Electranet as partners.

The project looked closely at the compliance and response of existing inverters to power system disturbances. The initial results suggested that over 50% of our inverter-based resource could behave undesirably (disconnection or power curtailment) if exposed to common grid disturbances like voltage sags.

Importantly, the challenge is not just existing inverters for generation integration, but also future energy storage inverter interfaces, electric vehicle chargers, or any other grid interactive interface that will be essential in delivering the grid of the future.

The next step is to examine how this can be managed when these inverter-based resources are scaled up to the levels projected in AEMO’s ISP, and then cost it.

Again, the imperative is to ramp up the development of new knowledge that is so urgently required to accelerate the energy transition. Importantly, this effort must be channelled into practical measures that can be implemented at scale.

With concerted effort and strategic investment, we still have time to develop the first and best inverter-based power system that the world can emulate. It could be one of Australia’s biggest contributions to the global energy transition.

From these little things, big things could grow.

Dani Alexander is the chief executive officer of the UNSW Energy Institute. Professor John Fletcher is the director of the UNSW Digital Grid Futures Institute.