Does the shallow end of the pond heat up faster than the deep end ? I have a pond 13 feet on one end and 2 to 6 feet on the shallow end and I was thinking of floating some of the polystyrene insulation panels in the water to shade it during the day. I plan on tethering them together so they do not float all over the place but I want them to be put in the right place. Any one know which end would be best ?

I'd definitely go shallow end. Deep water has thermocline & better thermal refuge. Also, shallow water shade may help to control weed issues.

I would try some of both deep and shallow. What % of the pond are you going to cover ? If substantial % then consider the effect of cutting off sunlight to plankton and food supply.