What happens to the grid when there is too much rooftop solar? South Australia is trying to avoid becoming a cautionary tale

May 19, 2022 | Case Study

South Australia residents are making progress on their goal of shifting power to renewable resources largely from home rooftop solar — already hitting 100% for one hour last year. But the reliance on solar creates problems for the grid. Insufficient solar production and the region needs to rely on Australia's national grid, potentially overloading an interconnector. Too many solar units sending power onto the grid at once, such as at noon, can increase the voltage to the point where it exceeds inverter tolerance, causing inverters to disconnect. South Australia Power Networks, the regional distribution system operator (DSO), is taking measures to manage these risks, including upgrading voltage management at major substations, offering a special tariff to encourage electricity use at midday, supporting regulations that require new inverters to have voltage ride-through capabilities, and disconnecting systems as a last resort. Most of these measures are reactive, managing solar power intermittency as it affects the subgrid. To be more proactive, the DSO joined with Solcast, Tesla Forecast Solutions, the Australian Energy Market Operator, EnergyAustralia, and Snowy Hydro to develop a more accurate forecast for the region's solar generation. The project was funded by the Australian Renewable Energy Agency for AUD 994 million (USD 744 million).