Grid-forming batteries and the loss of system strength
As coal retires, the grid loses a stabilising service it once got for free. Batteries with grid-forming inverters can replace it — if projects are specified for it from the start.
- System strength — the grid’s ability to hold voltage steady during disturbances — has historically come from spinning coal and gas turbines.
- Grid-forming inverters let batteries provide this service electronically.
- Specifying grid-forming capability at design stage can turn a storage asset into a network asset.
For most of the last century, grid stability came as a by-product. Large coal and gas generators spin heavy turbines in lock-step with the network, and that rotating mass resists sudden changes in voltage and frequency. Engineers call the resulting service system strength. As those generators retire, the grid loses it.
Why inverter-based resources behave differently
Wind, solar and conventional batteries connect through power electronics. Most existing inverters are grid-following: they measure the network’s voltage waveform and inject current to match it. That works well on a strong grid, but on a weak one — such as remote renewable energy zones, or island and fringe-of-grid networks — grid-following plants can struggle to ride through faults and may need to be constrained.
Grid-forming inverters work the other way. They set their own voltage reference and behave more like a synchronous machine, providing a stable waveform that other equipment can follow. Batteries are well suited to the role because they can respond in milliseconds in either direction.
From storage to network asset
The scale of the opportunity is growing quickly. Around 7 GW of grid-scale batteries are operating across the National Electricity Market, around 45 GW sits in AEMO’s connection pipeline, and AEMO’s 2026 Integrated System Plan lifts the 2030 grid-scale storage target to 33 GW. The Australian Renewable Energy Agency is also funding UNSW research into grid-forming storage and system strength.
At the same time, more than half a million Australian homes and businesses have installed batteries under the federal Cheaper Home Batteries Program, and those systems are increasingly aggregated into virtual power plants that support the grid.
What to specify on your next project
- Ask for grid-forming capability explicitly in tender specifications, including performance requirements for fault ride-through and inertia response.
- Model the connection point. Weak-grid studies early in design show whether grid-forming capability will be required by the network service provider.
- Plan for stacked revenue. System-strength and frequency services can sit alongside energy arbitrage, improving the business case.
- Consider island and remote grids. In Pacific and fringe-of-grid systems, grid-forming storage can be the key to running at high renewable penetration without diesel spinning reserve.
The NETS view
Grid-forming capability is moving from innovation to expectation. Owners who specify it now will connect more easily, earn more from their assets and help keep the grid stable as the generation mix changes.
Specifying a battery or hybrid project?
NETS provides system design, connection studies and technical specification for storage and renewable integration.
Talk to NETSNew Energy Technology Solutions · info@netsolutions.energy · +61 2 4721 8715