Surprisingly it appears not to be too far off standard solar panel efficiencies. According to this source[0], five nines silicon (5N) is called Upgraded Mettalu

Surprisingly it appears not to be too far off standard solar panel efficiencies. According to this source[0], five nines silicon (5N) is called Upgraded Mettalurgical-grade (UMG) silicon. According to this paper[1], efficiencies over 20% have been reached with UMG silicon. [0]http://www.greenrhinoenergy.com/solar/technologies/pv_manufacturing.php http://www.greenrhinoenergy.com/solar/technologies/pv_manufa... [1]https://www.sciencedirect.com/science/article/abs/pii/S0038092X21002711#:~:text=20.76%25%20record%20efficiency https://www.sciencedirect.com/science/article/abs/pii/S00380....