Rooftop Solar Exports Trial Extended to 2026 Amid Flexible Payment Innovations
An innovative project in South Australia, aimed at exploring alternatives to a potential “sun tax” on rooftop solar energy sent to the grid, has secured an additional year to continue after receiving a new short-term exemption from regulatory constraints.
The Market Active Solar trial, known as MAS, is examining how to incentivise individuals to limit their solar exports, as well as how inverters respond to commands from both network operators and retailers.
Continuation of Testing
The recent exemption from the Australian Energy Regulator (AER) permits SA Power Networks (SAPN) and Engie to carry on with their testing with 100 participants until December 2026. This trial builds upon South Australia’s leading initiatives to manage the excess supply of rooftop solar energy during peak sunny periods when production can outstrip demand, leading to low or even negative pricing.
It assesses the implications of SAPN receiving requests from retailers to reduce solar exports, which are then blended with its own flexible export limits before being communicated to the customer’s inverter.
Engagement with Retailers
Initially, the focus was on refining the network alongside inverter manufacturers like Fronius, SMA, and SolarEdge, as well as energy management provider SwitchDin. However, the current phase involves collaboration with retailers, with Engie and AGL actively participating and providing compensation to customers for reducing their export levels.
Engie’s objective was to determine potential savings, estimating they could save around $9,000 per megawatt (MW) of curtailed rooftop solar when wholesale market prices dipped to negative $100/MW. The findings indicated that actual savings were closer to $7,000/MW.
Compensation and Challenges
Customers involved with Engie are compensated with £10 per month for the income they would have made from feed-in tariffs linked to excess solar export, as well as a £100 sign-up bonus and an additional £50 for completing a survey at the end of the trial.
While Engie noted some technical hurdles—with around 12 per cent of sites experiencing issues with transmitting curtailment signals—communication with customers represents a significant challenge. As retailers compensate customers for the power not exported, transparency in communicating the potential earnings during curtailment periods is crucial.
Insights from AGL’s Experience
AGL’s findings revealed that sites with multiple inverters, batteries, or high energy demands did not respond as effectively to the five-minute curtailment instructions as simpler setups, indicating that local inverters may not immediately act on the instructions they receive.
Future Prospects for Solar Management
This regulatory exemption provides an extended opportunity for the AER to assess the trial’s effectiveness. The AER stated, “Through the MAS trial, SAPN is investigating new methods to enhance the value derived from renewable energy while optimising network asset utility,” underscoring the importance of the trial in developing solar management strategies that lead to efficient integration into the grid.
Such trials are possible in South Australia due to SAPN’s transition towards smart solar exports. As of 1 July 2023, new regulations require all newly installed or upgraded solar systems to be compatible with flexible export limits of up to 10kW.
Households that select the flexible export option can typically export the maximum amount that their inverter and the network can manage, reaching up to 10kW per phase. Conversely, those opting out are restricted to a fixed limit of 1.5kW per phase.
Current Participation Rates
During an update on the progress of the MAS trial in October, SAPN reported that approximately 90 per cent of participants are choosing the flexible export option, with around 138.4 megawatts of convertible rooftop solar now under their supervision.
