According to my Excalibur instruction book for dehydrating potatoes.Do you happen to know if those potatoes are cooked and then shredded or shredded and then cooked?
Use new potatoes, wash and steam for 4-6 minutes.
Cut french style, in 1/4" slices, 1/8" circles or grate.
Texture: Brittle or Leathery Temperature: 125℉/52℃
Time: 6-14 hours.
I personally and honestly don't think the time to do the above is worth it. For all the prep, just grating & rinsing fresh is the same amount of work. There would be no worries as to their shelf life, just in case you didn't thoroughly dry them. I really don't see a savings.
I also don't think that the amount of sodium phosphate, caramel and annatto are in sufficient quantity for me to worry about. Considering I may only have them once (OK, sometimes twice) a week or even less. They certainly are not on my weekly shopping list.
I'd rather save the limited shelf and freezer space that I have for items more expensive than potatoes.
If it's time before supper (or whenever it is that you want them) your concern, they can be peeled, put in a bowl of water, into the fridge, and then grate when time to cook. Or peel day before, grate morning of, supper time, squeeze, dry, cook.
About the only reason I would attempt it (other than just to see how I'd do) is if you would not have access to potatoes for 6 or 8 months.