Solar Forecasting and Grid Stability

Rapid changes in solar energy generation, often triggered by weather events like cloud cover, significantly impact wholesale electricity prices and grid stability. An event in Sydney on November 26 demonstrated this dramatically: thick, fast-moving clouds caused a sudden drop in rooftop solar output and a spike in household energy demand.

This led to a temporary increase in wholesale electricity prices in New South Wales (NSW) from a monthly average of approximately $75 per megawatt-hour (MWh) to over $20,000/MWh. Subsequently, as the sky cleared and demand eased, prices reversed, falling to nearly negative $1,000/MWh within an hour.

The Sydney event showcased how rapidly prices can swing, highlighting the critical need for advanced grid management in an era of increasing solar reliance.

The Role of Solar Forecasting

Solar forecasting is essential for managing electricity grids as the reliance on solar power increases globally. This technology predicts sunlight levels and cloud formations at high resolutions, such as 500 meters and 5-minute intervals, to anticipate fluctuations in solar generation.

Accurate forecasts help prevent grid instability and reduce price volatility by allowing other power sources to be brought online proactively, ensuring a more stable and predictable energy supply.

Australia's Leadership in Technology Development

Australia has emerged as a leader in developing advanced solar forecasting technology. Companies like Solcast, co-founded by Nick Engerer, pioneered "nowcasting" — forecasting sunlight (irradiance) in short intervals. This technology became critical as solar power grew to become Australia's largest single source of power.

The development of this technology was significantly aided by Japan's Himawari-8 weather satellite, launched in 2014. It provided high-resolution, frequent imagery crucial for cloud tracking. Solcast's data is now utilized by the Australian Energy Market Operator, 80 percent of network operators, and 80 percent of generator-retailers in Australia. The company's technology is also deployed globally, managing over 300 gigawatts of solar projects.

Australia's pioneering efforts in "nowcasting" have set a global standard for managing large-scale solar integration into national grids.

Economic and System Impacts

Solar forecasting helps reduce wholesale power price volatility, which can contribute to lower power bills by mitigating risks for electricity retailers.

It also plays a critical role in preventing grid outages by ensuring a continuous balance between energy supply and demand. For battery energy storage systems, accurate forecasting allows for optimized power sales during price spikes, generating significant revenue.

Future of Forecasting

Despite advancements, rapidly forming convective clouds like thunderstorms remain a challenge for current solar forecasting systems. AI models are emerging as a cost-effective and potentially equally effective alternative to traditional physics-based weather models.

Future developments may include leveraging data from distributed solar panels themselves to track cloud movement and further enhance forecast accuracy. This approach could provide high-resolution, real-time data to significantly improve predictions.