Solar Panel efficiency is usually NOT THE RIGHT QUESTION TO ASK.

One of the most common things people ask when they start to consider going solar or start to plan their life-changing solar expedition is which are the most efficient solar panels.  The important matter is not which solar panels are most efficient, but which solar panels are the best value for the money.
(But also take a look at the differing opinions in the comments section).

https://cleantechnica.com/2014/02/02/which-solar-panels-most-efficient/