They claim to achieve 99.999% purity on the silicon, so it sounds like they might do better than 6-9% on efficiency. But then again if they were anywhere near Earth produced panels, they would probably be saying that to everyone who would listen.
[0]http://www.greenrhinoenergy.com/solar/technologies/pv_manufa... [1]https://www.sciencedirect.com/science/article/abs/pii/S00380....
It's not like we have huge space constraints for small starts, I reckon?
The real challenge with solar power on the Moon remains the two-week day/night cycle, which means either massive batteries (impractical) or awkward polar cliff locations to minimize the hit.
https://www.nasa.gov/mission_pages/LADEE/news/lunar-atmosphe...