KY-040 Encoders

These are cheap, and you need at least 30 for the whole sim.

TRY TO FIND ONES WITH THREADS AND NUTS! It makes attaching to the panels much easier!

https://www.ebay.co.uk/itm/10pcs-Rotary-Encoder-Module-Brick-Sensor-Development-KY-040-Fit-For-Arduino/191739337554?epid=1991591645&hash=item2ca48e1b52:g:BsoAAOSw6dNWSUzg