Australia stands out as the country with the highest number of rooftop solar users per capita globally. With more than 31% of households in the national electricity market area utilizing distributed photovoltaic power supply, the impact on the electricity market is profound. Supported by state government incentives, Australian households and businesses have been consistently installing significant amounts of rooftop solar capacity annually since 2015. By the end of June 2023, the total rooftop PV capacity had surpassed 18 GW, exceeding the installed capacity of thermal coal units by 16 GW, making it the largest power type in terms of power generation capacity, accounting for 23% of the total installed capacity.

Queensland and New South Wales lead in rooftop PV installed capacity, while South Australia boasts the highest per capita rooftop PV installed capacity. In 2022, rooftop solar power generation in the electricity market area increased by 15% compared to 2021, with power generation more than doubling since 2018, representing 9% of the total power generation in 2022. Rooftop solar achieved a significant milestone on February 11, 2023, when it met 38% of the total market demand at 1 pm, setting a new record within half an hour.

The growth of rooftop solar energy in Australia has reshaped the daily power demand curve, with the minimum system load shifting to midday due to increased photovoltaic power generation. While rooftop PV power generation isn't traded through the electricity market, it indirectly impacts the market by reducing system power generation and altering the demand curve. The increasing prevalence of rooftop solar has led to more negative electricity prices in the Australian electricity market, particularly during periods of low demand and high renewable energy output.

The impact of rooftop PV power generation on system load significantly influences electricity market prices, particularly negative electricity prices. Factors such as fuel prices, thermal power unit operations, and renewable energy generation contribute to the occurrence of negative prices. The combination of rooftop solar and centralized photovoltaic power generation enhances the prevalence of negative electricity prices, as seen in the rising trend of negative prices in Australia over recent fiscal years. Notably, the summer months witness a higher concentration of negative prices due to increased demand for wind and solar power generation.

The convergence of rooftop PV power generation and negative electricity prices in locations like South Australia and Victoria have led to reduced electricity market value for rooftop solar surplus electricity. This diminishes the financial incentives for users to install rooftop solar panels, impacting the overall electricity market landscape. However, emerging trends such as home energy storage batteries, virtual power plants, and distribution network advancements offer opportunities to optimize rooftop solar usage and grid integration.

Technological advancements in home energy storage batteries and virtual power plants have the potential to enhance electricity grid reliability and security. By aggregating rooftop solar systems and energy storage solutions across households, virtual power plants can contribute to grid stability and reduce peak demand pressures. The bidirectional flow of electricity along the distribution grid due to the increasing number of rooftop solar installations necessitates reforms in transmission and distribution pricing to ensure equitable grid cost distribution.

As Australia transitions towards retiring thermal power units and adopting distributed rooftop PV systems, the power system's structural dynamics will undergo significant changes. The integration of larger-scale rooftop PV capacity and other emerging technologies like electric vehicles and household fuel cells will further shape the electricity market landscape. Lessons from Australia's experience in renewable energy deployment and grid stability provide valuable insights for China's power market development and energy transition.

In terms of policy formulation and market mechanisms, China can draw from Australia's market operation experiences to optimize electricity market rules, spur electricity consumption, and boost new energy adoption. By examining Australia's negative electricity price market mechanisms and aligning them with China's power market objectives, policies can be crafted to foster a more conducive environment for new energy development and electricity market reform. Embracing renewable energy technologies, enhancing grid infrastructure, and incentivizing consumer participation can pave the way for a sustainable and efficient power system transformation in both Australia and China.