LONDON, Feb 28 (Reuters) - The owners of Energia Group are looking for advisers to sell the Irish utility in a deal that could value it at up to $3 billion including debt, two sources with knowledge of the deal said.

The sale process by infrastructure fund I Squared is expected to begin after the summer, subject to market conditions, the sources said on condition of anonymity because the information is not public.

I Squared acquired Energia in 2016 for 1 billion euros ($1.08 billion) and unsuccessfully tried to sell it in 2018 and 2020.

The fund is betting that Energia's core earnings growth and interest for integrated utilities with a diversified portfolio of renewable and conventional power will draw buyers, one of the sources said.

I Squared declined to comment on Wednesday. Energia Group could not immediately be reached for comment.

Energia owns onshore wind farms with a capacity of 309 MW across the Republic of Ireland and Northern Ireland, 747 MW of combined-cycle gas turbine (CCGT) plants in Ireland, and supplies gas and electricity to nearly 800,000 clients, according to its website.

Infrastructure investors or utilities with a positive outlook on Irish macroeconomic perspectives are likely to be potential bidders, the sources said.

Energia, which had 1,111 employees as of Sept. 30, is also expanding into the data-centre business with a project in Dublin.

The company reported core earnings (Ebitda) of 145.8 million euros ($158.2 million) for the first half of the year, and has a total net debt of 336 million euros. It completed the refinancing of two debt emissions in July, replacing them with 600 million euros senior secured notes due in July 2028.

($1 = 0.9218 euros) (Reporting by Andres Gonzalez; Editing by Richard Chang)