Each morning when the sun rises, millions of solar panels installed across the country awaken and begin producing electricity.
The electrical output from Australia’s solar fleet grows as sunlight intensifies, peaking in the middle of the day before falling in the late afternoon as the sun drops towards the horizon.
That’s great news for more than three million Australian households with solar that are benefiting from power bill savings and access to emissions free electricity. But with so much solar generation happening at the same time many network areas are becoming congested in the middle of the day resulting in the technical limits (like voltage and thermal ratings) being at risk in the middle of the day.
Network businesses have typically managed this by placing static export limits of solar customers, commonly 5 kilowatts ‘per phase’. These limits constrain export all through the day, not just when the grid is congested. As more customers take up solar in a particular network area, these limits will need to be reduced to keep the grid safe. In some extreme cases, some customers are already receiving ‘zero export’ limits.
Variable, but predictable
Like the ancient Greek god Helios that drove his chariot across the sky every day, the sun’s daily journey contains some variability, but is also fairly predictable.
The daily patterns provide authorities with an opportunity to plan for the recurring scenarios to help stay within the technical capabilities of the electricity network, while also helping energy users to get the most value from Australia’s growing solar fleet.
Daily weather patterns can also have a huge impact on solar output and a static export limit set for the sunny spring day would leave lots of grid capacity unused for the rest of the year.
To understand how best to overcome the thorny challenges associated with integrating customer-owned energy devices like solar, home batteries and electric vehicles into the electricity network, a group made up of industry representatives, governments, market bodies and regulators has met regularly since 2018.
The Distributed Energy Integration Program (DEIP) has most recently tackled the issue of Dynamic Operating Envelopes, which would effectively increase the speed limits to allow more solar exports outside off peak times while ensuring safe limits are maintained when the grid is congested.
The DEIP, in a new report, explores how export limits can be more dynamic, taking account of daily weather patterns and local network conditions. This approach is referred to as ‘Dynamic Operating Envelopes’ and a number of network businesses are looking to offer these to their customers in 2022, with more to follow in the coming years. The report has 27 findings that are aimed at promoting national consistency and innovation and reducing power bills for all electricity customers.
Exports in the spotlight
The DEIP working group focussed on finding effective ways to manage solar exports to the grid and the role for flexible approaches to energy use, including making use of excess solar production in our homes to charge batteries, heat water or fuel electric cars.
Reprising the speed limit analogy, they agreed it is unnecessary to limit cars to 40 km/h school zone limits at all times, with electricity able to flow into the grid safely at higher rates when conditions allow.
When the network is stretched and cannot accommodate more solar exports, temporary limits kick in. Once the network congestion eases or the demand challenge passes, the limits are lifted so customers can benefit from exporting their excess power, boosting the use of renewable energy and helping all energy users to share in affordable power.
How will they help?
This new dynamic approach to solar exports would allow more solar homes to connect to the grid and export more power at certain times.
This would help to address the emerging issue of new solar homes having increasingly tighter limits applied to the amount of power they can export, or even being rejected from connecting to the grid at all.
ARENA’s Principal Policy Adviser Jon Sibley says variable limits would be an improvement for solar homeowners, who are currently subject to static limits at all times.
“A more flexible approach would ensure that customers’ exports are only constrained when the network is experiencing actual congestion so customers can then export more solar power outside of peak times,” Sibley said.
Flexible limits would allow more distributed generation like solar or batteries to connect to the grid, reducing emissions and driving down the price of electricity. This would help to share the benefits of solar with all energy users, including those that currently miss out on the bill savings and improved sustainability that solar offers.
Limiting exports at periods of high solar production would provide a signal to solar households, encouraging people to shift their energy production to the times of day when their rooftop solar is producing the most energy.
For network operators, a dynamic approach to managing energy exports would have significant benefits, offering a way to avoid costly network upgrades that would drive up electricity prices.
The underlying communications infrastructure provides a means to communicate with customer energy devices that can be used for a whole range of purposes like managing the grid during periods of potential power system frequency instability.
In the future, Dynamic Operating Envelopes could also be used to open up more network capacity for EV charging, enabling quicker charge times while reducing costs for all customers.
Increasing solar exports outside of peak generation times also mean more solar when the electricity wholesale market needs it most.
Making the case
The authors recognise there is work ahead to make the case for change and achieve buy-in from all stakeholders. This will demand that benefits be explained to consumers, who may perceive automated approaches as a threat to their solar earnings.
So far however, consumer groups like Energy Consumers Australia, who as a co-author of the report, have recognised the potential benefits and identified key initiatives to ensure consumers’ interests stay at the heart of this change.
Sibley believes dynamic approaches are likely to become the obvious choice for most customers, who will see the opportunity to improve the rate of return on solar and battery investments by exporting more power across more times of the day.
The report highlights a number of trials and demonstrations underway that can provide valuable insights, with a majority of Australian network operators currently considering the opportunity that Dynamic Operating Envelopes offer.
One trial underway in South Australia suggests that flexible limits may be rarely applied, with households able to export 10kW for 98 per cent of the time.
Research undertaken to inform the study found that a nationally consistent approach would be preferable, recommending that all stakeholders understand their role in this change and work together to ensure the best outcomes for consumers.
The report stresses that mandates should not compel people to participate in Dynamic Operating Envelope programs, and customers should be provided with the option to opt in or out when they want.