10% efficiency is about right for low cost solar cells that have been out in open air for a while. 20% is about right for affordable single crystal cells, and the theoretical maximum efficiency for silicon is 33%.
Getting significantly better than 10% is very expensive. Getting beyond about 25% is currently well beyond feasible for large scale power generation.
Getting significantly better than 10% is very expensive. Getting beyond about 25% is currently well beyond feasible for large scale power generation.