A construction permit for the Baltic Sea project is still required, but construction could begin in 2019. It is expected to be operational by 2026.
The permit allows for the use of turbines far bigger than those in production today. Maximum height has been set at 300 metres, and rotor diameters at 250 metres.
It is Polenergia's second offshore development. Baltyk Srodkowy 3, also 600MW in proposed capacity, was awarded an environmental permit in August 2016. It is due to begin construction in 2019.
Polenergia said a wind measurement campaign for both projects started in January 2017. "Thanks to very good wind conditions in the Baltic Sea, a more efficient use of energy and reduced equipment wear will be possible, making offshore wind farms a stable renewable energy source," Polenergia said.
"Based on expert calculations, if by 2030 we manage to construct wind plants with the total capacity of 6GW in the Baltic Sea, the Polish GDP will earn PLN60 billion (€14 billion) from it, and the labour market will be enriched with an additional 77,000 new jobs," said Polenergia vice president Jacek Glowacki.
In May 2016, Poland's government introduced a distance requirement law for onshore projects.
Onshore sites must be located at a minimum distance of ten times the turbine's height from houses and natural protected sites, in practice about 1.5-2km, criteria that observers say very few sites will be able to meet.