On Friday, Australia’s grid operator issued an unusual warning regarding dangerously low power demand. The grid managers expected the state of Victoria to experience extremely high levels of rooftop solar power production the following day. This led to serious doubt in their ability to maintain system stability.
Some data. In Australia, one in three households has solar panels connected to the grid, which makes many homes self-sufficient in solar power. This caused the operator to anticipate demand dropping below the threshold needed to keep the system stable.
In Victoria, the second richest Australian state, the power grid is designed to handle a demand of between 1,865 and 10,000 megawatts, with the usual demand being around 5,000. However, by midday Saturday, the Australian Energy Market Operator (AEMO) forecasted power demand to be just 1,352 MW, marking the lowest level in recent history.
Emergency measures. AEMO considered several options to stabilize the system during times of oversupply, such as disconnecting rooftop solar panels or limiting surplus power discharge. It also thought about reactivating decommissioned power lines to alleviate excess power.
Ultimately, it decided to notify owners of large batteries to keep them empty in anticipation of the oversupply of solar power.
Some context. With a combined capacity of more than 20 GW, rooftop solar is a significant source of electricity in Australia. Its increasing output reduces the demand for grid power, especially on sunny, mild weekend days when consumption is moderate.
Additionally, homes with grid-connected PV panels contribute surplus electricity in an uncontrolled manner, further challenging the grid’s stability during times of low demand.
Why is this dangerous? Electricity production must match real-time power consumption because it can’t be easily stored on a large scale. If demand exceeds supply, the power grid can become overloaded, leading to blackouts or damage to electronic devices and appliances. Additionally, thermal power plants need to keep running to stabilize the system.
Renewable energy sources complicate this process as they’re intermittent, leading to oversupply issues. To achieve a flexible grid dominated by renewables, more large-scale batteries are needed to store energy during times of low demand and release it when demand is high.
Pros and cons. While Australia didn’t experience serious issues due to the operator’s foresight, experts expect the problem to worsen. It may require reforms in the electricity market or more efficient management of surplus rooftop solar energy, similar to what has been done in California.
The grid limit is no longer reached during peak demand in summer due to the use of air conditioners, but rather on sunny, mild days like Saturday. With solar power breaking records, Australia already meets up to 70% of its energy needs using renewable sources.
Image | Benjamin Jopen
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