Mullafarry battery storage consent clears path for 320MWh Mayo project

Mayo County Council has granted planning consent for the Mullafarry battery storage project near Killala in North Mayo, clearing a planning hurdle for SSE Renewables and its 80MW/320MWh battery energy storage system (BESS). The project still requires a final investment decision from SSE before it proceeds, but consent is the precondition everything else depends on.

The approved scheme would place the facility at Killala Business Park in North Mayo, on an SSE-owned site directly adjacent to the company’s existing 104MW Tawnaghmore Power Station. Locating a large BESS next to an operating generation asset is a sensible grid topology choice: the connection infrastructure is already there, and the operational relationship between generation and storage can be managed from one location.

What the Mullafarry battery storage consent actually approves

Here is where the detail matters. The original consent for the site dates to 2018 and has since expired, so this is a revised application rather than a first-time approval. According to SSE Renewables, the approved design covers between 26 and 38 battery units, which sits at odds with the headline figure of “up to 64 battery storage units” SSE used to describe the project. The upper end of the approved range is considerably lower than that marketing number, and developers and journalists alike should be cautious about which figure ends up in the public record as the project’s scale.

Each battery unit would be accompanied by associated heating, ventilation and air conditioning systems and supporting infrastructure. The system is rated at four hours of reserve electricity capacity, meaning the 80MW power rating can be sustained for that duration before the batteries need recharging. That is a commercially useful duration for balancing services, though not exceptional by international standards for long-duration ambitions.

Timeline and investment decision still to come

SSE Renewables has said it is hoped construction could commence in 2026, with project completion expected in 2028. The company estimates construction would take up to two years, which is consistent with that window. But the qualifier matters: none of those dates are confirmed. A final investment decision has not been taken, and until it is, the 2026 start is an aspiration rather than a commitment.

Ghislain Demeuldre, Head of Onshore Wind, Solar and Battery Development at SSE Renewables, welcomed Mayo County Council‘s decision. ‘This decision gives SSE the potential to significantly increase the energy output we can deliver through the project,’ he said. ‘By storing electricity when supplies are high and making it available when needed, Mullafarry could help support a more secure, affordable and homegrown electricity system for Ireland.’ The conditional framing throughout that quote is accurate: this remains a project with potential, not one with a confirmed delivery date or capital commitment.

SSE Renewables also pointed to local economic benefits, citing jobs during the construction phase and ongoing commercial rates payments to Mayo County Council as part of the project’s contribution to the area. Those are real, if modest, community returns. The larger value proposition for Ireland is operational: a 320MWh asset of this size would provide grid flexibility, supporting the integration of variable renewable generation and improving security of electricity supply as the island’s power system moves away from fossil fuels.

The Mullafarry BESS sits within a broader Irish storage pipeline that is expanding rapidly as the grid operator works to manage higher shares of wind and solar. Planning consent is a necessary condition for that pipeline to materialise. Whether SSE pulls the trigger on the investment decision, and whether 2026 holds as a construction start, are the tests that follow.