This is a 1 axis solar tracker (make two if you need 2 axis) that fits inside a 1/2 pint glass jar. I needed a waterproof tracker that can stand up to the elements. I used a stainless steel jar lid and ring to add longevity. Try to find a glass jar with a clear bottom if possible. This sensor uses two PDB-C139 photodiodes and two LTC 1050 op amps to provide a voltage level that you can easily read with an analog pin. I used an Arduino Nano but any Arduino would work. Simply compare both outputs to see what sensor is in full sun and what sensor is shaded. A light defuser is needed as the output of the PDB-C139 can be full when only 1/2 of the senser is exposed to sunlight. I used Teflon for my light defuser however I've also used a white plastic cover off of a broken shop light with equal success. Cut the light defuser to the same size as the teflonholder piece. I included the scad file for the teflonholder in case you need to adjust the thickness.

The vert solar holder piece bolts on with the lid and keeps the jar/sensor in alignment.
I also included the artwork for the PCB and see my YouTube channel (JTandHZ) on how to make a PCB if needed. I'll try to follow up with a DIY video ASAP.
This circuit was based on the: https://outsidescience.wordpress.com/2012/11/03/diy-science-measuring-light-with-a-photodiode-ii/

MakerGear

MakerGear M2

No

Yes

Med

50