Wicklow County Council has refused planning permission for a solar farm and two warehouses at a large-scale data centre campus in Arklow.
Irish-owned company Echelon had planned to build the projects as part of the DUB30 data centre at Kish Business Park.
The developments on the site consisted of two warehouses of more than 2,400 square metres in size and a solar panel farm across almost 40 acres.
The company, which also has operations in the UK, North America and Europe, submitted the planning application on 9 July.
In a decision last week, Wicklow County Council refused permission on the grounds that it considered the development was "not in line with the zoning provisions or the policies and objectives" of the County Development Plan or the Local Area Plan.
In the planner's report, the council said the solar farm array would "contravene the zoning objectives for this area."
It said the development would "result in the underutilisation of employment lands, would not achieve a suitable jobs ratio, and would set a precedent for further inappropriate development at this location".
A spokesperson for the company said Echelon is making "no comment on the decision at this time".
DUB30 is among two data centres being developed by Echelon in Arklow, as part of a €3.5 billion investment.
The second, known as DUB20, is located on the site of the former Irish Fertilisers Industries plant at the Avoca River Business Park.
Taoiseach Micheál Martin attended the launch of the planned facilities in May, in an area where the grid is not constrained.
Mr Martin had described the campuses as "the model for future data centre development in Ireland".
Echelon said the projects would create 2,600 jobs during the construction phase and 715 permanent roles at the two facilities when they are operational.
The company said the project would also have the capacity to generate and dispatch electricity to the national grid when needed.
