How do I clean my set (>30) of PET bottles? I'm dealing with dried beer and yeast residue from my previous batch. I doubt I can use hot water, since it would deform the plastic. Do I need to scrub the inside of every single bottle, or is there an easier/faster way?
Warm water from the tap will not deform the bottles. If you are worried about it you can temper the water with cooler tap water. Use hot water to dissolve some oxyclean or PBW. Temper it with the cooler water. Make a big enough batch to soak the bottles in overnight and you'll be fine. No scrubbing.
I regularly do this in a large plastic bin or a large kettle.
The first trick is never to let beer and yeast dry in the bottles. Rinse them out as soon as they're empty and leave them full of water until you can clean them properly.
PBW is more more effective than percarbonate (oxyclean), but percarbonate is cheaper. In either case 60 Centigrade is the best compromise between effective cleaning and not damaging PET.