European power grids are losing inertia fast. As gas and nuclear generators clear in the market less often, the spinning mass that once stabilised the grid frequency is reducing. Inverter-based resources (wind, solar, and grid-following BESS) currently provide no inertia at all. The result is a grid that responds more violently to disturbances, where smaller events trigger larger frequency swings. The worst-case scenario - a continental system split leading to widespread blackouts - becomes harder to plan for.

Grid-forming inverters change this. Unlike grid-following inverters, which take their frequency reference from the grid, grid-forming inverters can set voltage, provide fault current, dampen oscillations, and inject active power during frequency events within milliseconds. Their inertia constant is a software setting, not just a physical constraint. BESS assets can be tuned to provide exactly what the system needs (within their technical limitations).

Grid operators in GB, Australia, and Germany are each responding differently - but all are now creating commercial incentives for grid-forming BESS. We look at what those markets pay, and what it means for project economics.

Key takeaways