in poland specifically:

• if you want to sell energy to grid, terms absolutely suck
• grid is often overloaded in the summer in areas with large # of pv installations, meaning too high voltage, meaning inverters shut down;
• there was a years long robocall campaign that sold these installations. pv installations are subsidized so more people could set it up and middlemen like this appeared

if you want to reduce your carbon footprint, or you want to use it all without selling energy, or such, you’ll be fine. if you believed robocalls that say that it will get you net passive income from that, tough luck

if you want to get a better deal, get solar water heater. it works always if there are no clouds, even in winter you can get 40C on a clear day