Construction of the plant, E.ON's biggest in Hungary to date, started in early 2009, with Siemens Energy acting as the main contractor. The Gönyü plant will have an efficiency rate of 59%, among the highest in Hungary's power generation sector. Its capacity accounts for almost 5% of the nationwide total of around 9,000 MW.

"This is one of our major power generation investments in this part of Europe," Bernhard Fischer, CEO of E.ON Generation GmbH said at the inauguration ceremony. "The plant is setting a new benchmark for power generation in Hungary."

The power plant site was designed and built so that it can accommodate another similar-sized power plant block, which would take total capacity to more than 800 MW. While many industry players assume that a second Gönyü unit will indeed be built later this decade, company officials stressed that no decision has yet been taken.

"We are constantly monitoring market developments to see if we can invest profitably in a new unit," said Zoltán Katona, managing director of E.ON Erőművek Kft.

As the plant's output can be raised or lowered flexibly, it will operate mostly as a peaking plant – meaning it will run mainly during daytime on weekdays, when demand for electricity is highest and can change quickly.

The opening ceremony was also attended by Hungarian President Pál Schmitt and state secretary for energy affairs János Bencsik, who both highlighted the power plant's role in the reliable supply of electricity to Hungarian households and industry.

"The plant will significantly improve the flexibility of the Hungarian power system," Bencsik said. "The Gönyü plant is filling an important gap."