Pinergy is increasing its electricity prices by 7.6%.
The change will come into effect on September 14th, and will result in a rise of about €169 per year.
It says the continued volatility in energy markets has pushed costs to a level it can no longer absorb.
Pinergy's previous price increase came last October.
Pinergy CEO, Enda Gunnell, says: "Unfortunately the continued volatility in wholesale energy markets has pushed costs to a level that we can no longer absorb. Our hedging strategy has helped protect customers from much of the pricing volatility to date, but the scale and duration of what we're seeing in wholesale markets means a change is now unavoidable.
"We understand this comes at a difficult time for many households, and we would encourage any customer who is concerned about their bill to get in touch with us directly for support."
Daragh Cassidy from Bonkers says: "This new isn't surprising, unfortunately.
"Over the past few months, wholesale electricity costs have begun to creep up again, largely due to the renewed conflict in the Middle East.
"Year-to-date wholesale costs are now almost 20% higher compared to 2025, and are among the highest in the world.
"On top of this, we've seen fees for the management and upkeep of the electricity grid increase too.
"So the fear was that we'd see more price hikes as we got into autumn. And it's likely most other suppliers will follow suit before the end of the year."