Onshore and offshore: what’s different?
Both turn moving air into electricity. Their locations change the engineering, consenting and grid connection work around them.
Reviewed 2 November 2026 · Republic of Ireland
Onshore means on land
An onshore wind farm needs a suitable wind resource, space, access and an electricity connection. Its planning assessment considers the particular site and proposal. The turbine is only part of the project: cables, access works and the connection also matter.
Offshore adds a marine setting
An offshore project places turbines at sea and brings electricity ashore through cables. It also needs coastal and onshore infrastructure to connect to the electricity system. Marine permissions are a distinct part of development: SEAI’s consenting service explains the relevant licences and permits.
SEAI’s Maritime Area Consent guidance states that a consent is needed before applying for development permission in the maritime area. A consent is not the same as permission to construct and operate a completed wind farm.
Capacity is not output
A project’s nameplate capacity describes its rated generating power. Actual production depends on the wind and operating conditions. A proposed project, a consented project and a working project are different things; a capacity headline should not be read as today’s generation.
This index displays EirGrid’s reported wind output. It does not split the operational total into onshore and offshore generation or infer whether a proposed development has opened.