Called Viridian Group until a 2019 rebranding, Energia owns and operates around 1 gigawatt of renewable and conventional power generation in the Republic of Ireland and Northern Ireland, and provides gas and electricity to over 750,000 customers, according to its website.
A sale process for Energia is expected to begin later this year, subject to market conditions, according to four sources, who spoke on condition of anonymity as the information is not public.
I Squared and Energia declined to comment.
I Squared acquired Energia in 2016 for 1 billion euros (900 million pounds) and ran an unsuccessful process to sell it in 2018. Since then, Energia has sought to boost its renewable energy portfolio amid a push by European policymakers to make power production greener.
European oil producers are also pivoting away from hydrocarbons, as they aim to make themselves holistic energy companies, adding a new group of possible buyers for Energia.
BP PLC said last week it planned to reduce its oil and gas production by 40% by 2030, while massively expanding into renewable energy, aiming at a 20-fold increase in renewables generation over the same period.
When Eneco was sold earlier this year to a consortium led by Japan's Mitsubishi Corp for 4.1 billion euros, the Dutch energy firm attracted interest from other oil producers, including Royal Dutch Shell PLC.
In the year to March 31, Energia Group generated earnings before interest, tax, depreciation and amortization (EBITDA) of 157.2 million euros, and had net debt of 714.3 million euros at that time, according to its annual report.
By David French, Clara Denina and Arno Schuetze
