1. The problem statement, all variables and given/known data Hey everyone, as part of a final year project I am looking at the economic feasibility of solar panels and whilst I have solar data for radiation intensity on flat surface, longitude (and plus or minus 15°) and 90° Im trying to find a calculation of intensity at any given angle. Ive been looking in books and they do sort of give and answer but Iv'e been struggling to understand the books for this section and haven't been successful in gaining a real equation. Also, the equation seem to relate to when really little info is known. I already know the intensity of m^2 of flat ground. So what I'm trying to find is if it's possible to calculate the intensity on an incline given that 0° intensity is known. 2. Relevant equations This is what Im trying to figure out, if there is a direct equation from known 0° to any desired angle 3. The attempt at a solution I've been looking in books and on the internet but have struggled to understand there description. Im looking for some personal help to help me figure this out!