The European Investment Bank (EIB) is lending up to zł946 million (£164m) to modernise power grids in Poland.
Polish energy company ENEA S.A. will use the cash to upgrade and extend electricity networks in the north-west of the country.
This investment programme will be carried out between 2015-2017 to boost energy security in the region.
The firm will construct or refurbish 460km of high-voltage and 3,800km of medium-voltage and low-voltage lines and cables.
Up to 3,300 transformers will be installed or upgraded.
The company will distribute 13% of the electricity consumed in Poland and connect around 45,000 new system users, improve the reliability of the electricity supply and reduce losses.
EIB Vice-President László Baranyay said: “The project will ensure a secure supply to new customers through the expansion of the company’s electricity network.
“This loan confirms the EIB’s commitment to the modernisation of the Polish energy sector, which is necessary for the successful economic development of the country.”