I am building a 2 axis solar tracker. In order to measure light intensity I am using 4 LDRs (up, down, left, right). Light sensing part is built on an independent stripboard (my future intention is placing this part on the front of the panel and Arduino on the back to protect it from direct sun exposure).
Program and circuitry seem to be working well, but when I point to an even light source, readings from the 4 LDRs are not the same. To be sure that light is even on the 4 LDR, I surround sensing piece with white cardboard and then I use a white area on my LCD monitor as light source.
On my code, I take several measures from each LDR and average them, to remove noisy readings. Unfortunately, readings keep being different.
4 LDRs (2-axis)
Light readings. Notice cardboard to avoid other light reaching LDRs. On the screen, the number of "U,D,L,R" is proportional to light reading (kind of bar graph). Number at the end of line is analog reading (0-1023).
Has anyone experience designing this kind of solar tracker? Can the problem be originated by the components themselves? How can be this problem worked out in order to have a precise sun tracking?