So, here's the deal: I'm trying to complete the publishing of a paper dealing with my thesis from almost two years ago, and I finally wrote a program that I believe will tell me how different geometries will influence the outcome. Here's the setup, I am modeling the radiation that goes through the cover of a solar still (google WaterCone for an example of what a solar still is) and is absorbed by the basin. In order to verify that my ray tracing code is functioning properly, I have performed three experiments with small, polycarbonate "covers" placed over a solar cell. The solar cell is given a small load and the voltage over the load is measured over the course of the day. Assuming the voltage is proportional to the total radiation flux seen by the cell (which may not be the case, I'm not certain), the radiation distribution over the course of the day does not match what I would expect it should according to my ray tracing analysis. Attached is one of the data files (data file 1, with the data used to approximate the flux given the maximum solar radiation that day). The behavior as you may note, drops down a bit and then comes up in a small hump at solar noon. While, for the ray tracing done to approximate the same conditions, there is no center hump, it is one single curve without the jump at midday. Similar midday behaviors can be seen in the other covers (all are wedge shaped), as the back plate reflects some light that would otherwise be lost onto the solar cell. Data files 2 and 3 are also included. Please note, there remains some fine tuning to be done to get them to match up a little better, but the general behavior of the ray tracing model will not change even after the fine tuning. Any help anyone can give me would be greatly appreciated (even if that help is "go ask somebody else who might know"). I can upload ray tracing codes if anybody here is equipped to understand them and troubleshoot them, but I'm guessing nobody here would have any experience with them, so redirection to an appropriate site/forum would be acceptable as well.