steering controller for solar panels

Hi we need to make several controllers for photovoltaic panels. what we guess is needed is 2 light sensors (or small pv's)set at 90 deg to each other and a circuit to compare the outputs and when one is greater than the other by a setable amount to switch a relay contolling a small 12 volt reversable motor which steers the panel until voltages are equal when it switches of and is capable of doing the same in the opposite direction depending on where the sky is brightest. the actual 12v motor and related engineering I can see how to make it's the control system I have little idea about. We have 3.5 kw of panels assembled in arrays of 4 x 120 watt 7.5 amp panels giving us 30 amp per array on axial mounts so we only need 2 axis control ie. east to west. several of our friends also need the same circuit as we work around the festivals during the summer. see **broken link removed** or sams sauna on facebook for who we are. thanks mark

We just finished one, and the parts are (or soon will be) on order. https://www.electro-tech-online.com...ing-me-issues-appreciate-anyones-help.103413/

A lot of development went on, so if you want just the final result skip to the end.