The internal reflectors will enhance the overall efficiency of the solar still.

Here is a good article for you on this topic:

Title: Enhancing the stepped solar still performance using internal reflectors. It appeared in the Desalination Journal, Volume 314, 2 April 2013, Pages 67–72. Here is the URL to download this article:

http://www.sciencedirect.com/science/article/pii/S001191641300012X

Hope this helps answer your question.

Professor Yehia Khalil

Yale University

USA