Relatively low amounts of wind and sun, high seasonality. Some of your closely neighboring countries are in a similar position.
You can get a feel for this at my favorite simulation site, https://model.energy/
Poland does have lots of salt under it, which bodes well for hydrogen storage in solution-mined caverns.
Because of Poland's unfortunate renewable position, it's understandable that nuclear is still strongly considered there. But that's not really going to help Poland compete globally against countries with better resources. If solar can provide power for $0.013/kWh in UAE, it's tough for Poland's heavy industries to compete with that with more expensive nuclear.