Australia is one of the countries leading in renewable energy. Currently, 3.5 million rooftop solar systems are installed with a 20GW potential generation capacity. The switch to renewable energy is very much welcome, especially as the consequences of climate change are being strongly felt worldwide.
However, the rising number of rooftop solar systems installed is also putting a lot of pressure on the grid. Now, it can be felt and seen that Australia is hitting a fundamental physical problem with renewables.
As renewables get past the capacity in grid concentration, problems arise as they compromise the viability of dispatchable power and storage costs.
Hence, the Australian Energy Market Operator (AEMO) has tapped into their last resort to ensure energy is distributed across the nation—a rooftop solar switch-off.
What is a rooftop solar switch-off
Last week, AEMO chief Daniel Westerman called for an emergency rooftop solar switch-off mechanism across Australia’s main grid to better control “more than seven Eraring power stations” worth of solar PVs.
According to Westerman, the amount of generation today doesn’t respond to market or operational signals, which poses a challenge.
The need for a rooftop solar switch-off
When there is an excessive amount of solar energy feeding into the grid, especially during favourable weather conditions, it can decrease the grid’s load to the extent that there isn’t enough spinning reserve capacity available to meet the operational and contingency reserve needs.. This puts the grid’s stability at risk because overgeneration may lead to over-frequency issues that will trip generators off the grid, which could lead to blackouts.
The most viable thing to do now is to disconnect solar to ensure the stability of the grid and secure supply. This approach enables the maintenance of enough traditional spinning generation with inertia still operational, which enhances the grid’s ability to handle fluctuations between supply and demand without causing stability problems.
Another challenge of renewables is that it is not dispatchable. When renewable sources are active, such as solar power harnessing sunlight energy, they operate at their maximum capacity, and their output cannot be easily reduced or adjusted..
Instead of disconnecting a property from the grid, the switch-off is a solution that allows homes to run solely on their solar output. Otherwise, the excess or lack of power produced by your solar panels could damage appliances, unless all homes have home battery systems with sufficient charge and discharge capacity that can absorb fluctuations.
A push-back
The rooftop solar switch-off has been met with several push-backs when it was first introduced. Critics say that it is a regulatory overreach and a “blunt instrument” that would ultimately cost consumers.
Some say that the government and market bodies should focus on increasing the deployment of smart, dynamic technologies to modernise the grid instead of using cut-offs.
However, this didn’t faze AEMO who said that, whilst the grid can handle high levels of rooftop solar generation most of the time, there are times when a combination of specific grid stresses with high rooftop solar generation will be a risk to the security and reliability of energy supply.
How the rooftop solar switch-off works
In the event of a rooftop solar switch-off, AEMO will issue a notification one day in advance to give the market time to prepare and respond. However, the notification may be issued right away during unexpected conditions.
The next notice will be the confirmation that operational actions are taken. Following the initial notification of AEMO, the market should take the necessary steps to maintain system security which involves shutting down large power plants.
The third notice signifies some rooftop panels are being prevented from generating as a last resort to protect system security and reduce risks.
For consumers, the orders will be sent via networks to the rooftop solar system’s smart inverter.
The impact on homeowners
During a rooftop solar switch-off, households are not impacted right away. Before homes are impacted by this, all other tools are to be exhausted.
South Australia (SA) was the first state to adopt the solar switch-off in 2020 with The Smarter Homes Program in place. The program ensures that the incoming fleet of new rooftop solar systems can adapt to grid faults, be subject to changing expert limits, and be switched off if necessary.
SA was also the first state to experience a solar switch-off in 2021 that affected over 12,000 households in Adelaide. In 2022, it was used again during a rare “islanding” of the state grid following heavy storms that brought at least one transmission tower and caused several transmission lines to trip.
In Western Australia (WA), all new and upgraded rooftop solar systems with 5kW inverters have been required to be capable of being remotely managed in emergencies.
The solar switch-off is now coming to Victoria. The state Labor government has announced an emergency backstop for new, upgrading and replacement rooftop solar systems less than or equal to 200kW in July 2024.
Alternative solutions to a rooftop solar switch-off
While the solar switch-off is considered a necessary system to protect energy infrastructure, there are alternative methods to better regulate the grid.
Community solar batteries
It is known that many are still opposed to the switch-off and are vocal about the alternative solutions. One is community battery storage systems.
Centralising storage mitigates waste, enhances grid stability and promotes energy sharing within communities, making it an eco-friendly and cost-effective solution to address the intermittency of rooftop PV systems.
These systems also have the potential to reduce strain on the grid, lower energy costs, and provide a degree of energy security during grid disruptions or emergencies.
Pumped hydro
Another one is pumped hydroelectric energy storage, considering the varied topography of the country that creates a unique advantage for this technology. Surplus electricity generated during the day can be used to pump water to an elevated reservoir.
During periods of reduced solar generation, the stored water is released, generating hydroelectric power. This kind of approach offers a reliable and grid-friendly energy source during the night and on cloudy days, mitigating solar power fluctuations.
Additionally, pumped hydro also offers a substantial storage capacity and can be integrated with renewable energy sources.
Demand-side management and grid flexibility
Demand-side management and grid flexibility offer a dynamic alternative to a rooftop solar switch-off. By employing smart grid technologies and real-time monitoring, demand-side management allows for optimised energy consumption patterns, encouraging households to use their power when it’s most abundant and save it for later use.
Grid flexibility complements demand-side management by integrating various energy sources and storage systems, ensuring a reliable power supply at all times.
Advanced grid technologies and forecasting tools
These innovations allow real-time monitoring of energy supply and demand, facilitating seamless integration of solar power into the grid.
By accurately predicting solar generation patterns and consumer energy usage, grid operators can adjust power distribution in real-time. This approach minimises the need to curtail solar power, ensuring a more consistent and reliable electricity supply.
The phenomenon of solar switch-off in urban environments represents a pressing challenge as the world transitions towards renewable energy sources. The intermittent nature of solar power, particularly during unfavourable weather conditions and at night, underscores the necessity for innovative solutions. However, as explored in this discussion, there is reason for optimism.
From the growing adoption of battery storage systems and energy sharing at the community level to the potential of pumped hydro and advanced grid technologies, a range of creative solutions are emerging to minimise solar switch-off.
These innovations not only promise to ensure a more reliable and resilient energy supply but also support sustainability and environmental objectives.
As urban populations continue to grow, and the demand for clean energy rises, we must harness these innovations to surmount the challenges of solar switch-off and propel our cities towards a more sustainable, dependable, and greener energy future.
Energy Matters has over 17 years of experience in the solar industry and has helped over 40,000 Australian households in their journey to energy independence.
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