>>674999The most popular version seems to be meant to be mounted on a bicycle. The convection that will be produced thanks to the speed of the bicycle is probably going to help a lot.
It's not trivial to calculate exactly how efficient it will be under different conditions, but obviously it is going to be more efficient the higher the temperature and the higher the humidity. If we for the moment assume that the peltier device is extremely cold we get a higher limit in that the volume of water is proportionate to the absolute humidity. Now, obviously 27 ounces per hour is under the best conditions they tested it in, so probably 40 degrees centigrade (104F) and 90% relative humidity. The ambient absolute humidity is then around 50g/kg. Now your moderate conditions might be 20C (~70F) with 70% humidity. The ambient absolute humidity at this point is around 10g/kg. So with our approximation, it would under these conditions produce around 5 ounces per hour.
Note that this is a best-case approximation. In all likelihood when it's colder, the condensation is going to be less efficient and the panel will produce less juice for the peltier device. At lower temperatures it's going to be virtually useless.