Most of the 5,000 homes and businesses that lost power during lightning and thunderstorms overnight had their power restored by lunchtime, according to ESB Networks.
The worst affected areas were in the south of country and included Bruff, Co Limerick; Athenry, Co Galway; Bunclody, Co Wexford and Tullow, Co Carlow.
Hundreds of homes in Donegal, including Glenswilly, Letterkenny, Convoy, Creeslough and Dungloe also lost power during the storms.
It is understood power cuts came after lightning strikes caused faults on the electricity grid.
The company said power had been restored to the majority of affected areas by 2pm on Saturday.
It said crews would continue to work on the remaining faults and said it expects to restore power to all affected customers on Saturday.
Lightning storms also killed a number of sheep on Friday in the Co Donegal village of Drumkeen.