New provisional data from EirGrid shows that 42% of electricity in September came from renewable sources.
EirGrid said the majority of renewable electricity generated last month came from windfarms, which accounted for 34% of all electricity used in Ireland.
Total generation from wind energy amounted to 920 GWh (Gigawatt hours), compared with 776 GWh last September.
Some 97 GWh of electricity came from grid-scale solar last month, which accounted for about 4% of electricity generated.
Elsewhere, 37% of electricity came from gas and 20% was imported.
Overall electricity system demand stood at 2715 GWh for September, up slightly from August.
EirGrid said that the electricity grid can accommodate up to 75% of electricity from renewable sources at any one time.
Diarmaid Gillespie, Director of System Operations at EirGrid, said that wind energy represented the vast majority of renewable generation last month, which demonstrates the continued importance of this source of electricity for the power system.
"As we head towards the winter months, we expect the fuel mix to change, with wind generation being more dominant, and a marked increase in demand for electricity, particularly after daylight saving ends and the clock change at the end of October," he added.
