Prime Minister Kyriakos Mitsotakis has inaugurated the largest standalone battery storage plant yet built in Greece, a 330-megawatt facility near Larissa that its developers call one of the biggest in Europe.
The plant, in Nea Karyes, was built by Metlen Energy & Metals and the Karatzis Group, and cost more than €170 million.
It holds 790 megawatt-hours of storage, according to company figures. A standalone plant stores power from the grid when supply is plentiful and returns it when it is scarce, helping balance a system with growing solar and wind output.
"I am especially proud that we are inaugurating the largest standalone energy storage facility in Eastern Europe, and one of the largest in the European Union," said Evangelos Mytilineos, Metlen's executive chairman.
Other officials have described it as the largest in Greece and one of the biggest in Europe, so the regional claim is the company's own.
Mr. Mytilineos tied it to industrial costs.
"We cannot talk about reindustrialization without answering energy costs," he said. "And we cannot talk about energy security without investing in the infrastructure that will let us use our own resources."
Antonis Karatzis, chairman and chief executive of the Karatzis Group, called it "the starting point of a new era" for his firm.
"Without storage, there can be no truly effective energy transition," he said.
Storing surplus power for when it is needed is "decisive" for grid stability, he said.
The project comes as Greece, which already generates more than half its electricity from renewables, struggles with midday surpluses that go to waste while evening prices rise.
Mr. Mitsotakis, who is seeking relief from Brussels for households facing high energy costs this winter, said Wednesday that storage, networks and interconnections are essential to using clean energy effectively.