The Teach Solais (Lighthouse) in Inis Oírr was built in the middle of the 19th century on foot of a request by the Galway Harbour Commissioners. The request was approved by the Corporation of Trinity House in London which was the body responsible for safety at sea at the time. It went into operation in 1857.
The position of the Lighthouse is 53°02.797′ North 09°31.613′ West and its height is 34 metres. The tower and dwellings associated with it were built of local limestone.
The Lighthouse was automated in 1978. It was converted to electricity, using a mercury vapour lamp as the light source in the 1913 optic, and monitored by radio link.
The latest upgrade in 2014 introduced a new light emitting diode (LED) light to reduce energy consumption and operating costs. Its rotating mirror was removed and preserved for heritage purposes.
The light range is 18 nautical miles White, 11 nautical miles Red. The red sector of the light highlights the danger of the Finnis rock (upon which the Plassy struck). The lighthouse is maintained by the Commissioners of Irish Lights and you can find further details there.