ATHENS, Sept 23 (Reuters) - Greece's biggest power utility Public Power Corp (PPC) on Thursday formally named Macquarie as the preferred bidder for a minority stake in its fully-owned power grid operator HEDNO.

PPC shareholders will take a final decision on the bid at a meeting scheduled for Oct. 19, PPC said.

PPC earlier this month said the offer by Spear WTE Investments Sarl, a member of the Macquarie Infrastructure and Real Assets Group, valued the 49% stake at 2.1 billion euros ($2.46 billion), including debt of 804 million euros, making it the highest among four groups which issued binding bids.

PPC, which is 51% owned by the state, has said it will use the sale proceeds to reduce debt and boost its footprint in renewables.

HEDNO operates a 242,000 km long grid, which brings electricity to about 7 million households and businesses across Greece. PPC expects a new investor to help to upgrade the grid, which mainly consists of overhead cables susceptible to failing in adverse weather. ($1 = 0.8519 euros) (Writing By Michele Kambas. Editing by Jane Merriman)