This is the most efficient way to keep stuff cold and to 'make cold'. You use electricity to directly make ice with this unit, making cold air in a freezer to freeze ice cube trays is a horrible waste of energy. This makes ice directly from contact the refrigeration evaporator. You make the ice, then you put it in a really good "5 Day" cooler and keep your food / beverages cool. OR you put the ice directly in your drink, that is the most efficient. It makes 26.4 lbs of ice a DAY (24 hours), So about 1 pound per hour, it holds just over 2 pounds of ice, so get the ice out every 2 hours. It makes its first ice in about 10 minutes. I am drinking a drink with ice made from one of these as I am typing this. These ice makers are Harris approved. You'll love the heck out of one. I use one everyday except in the winter.
Well, presumably, if it works during a power down scenario, then it might work pretty well in an off grid scenario too. The above quote is about a particular ice maker. I don't know how much it scales up in terms of larger ice makers, but for the purposes of this post, I will assume it does.
Cold air is heavier than warm and and it sinks, so I think it should be possible to have a j-tube, or even just a L with a little reservoir at the bottom for condensed water to collect. The ice goes around the j-tube. The are a lot of versions of this type of thing on youtube. They usually use a fan to force air past the ice. What I am thinking of here is how to get the condensing air to do most of the work for you, so you don't need to worry about a fan. I suppose the upright portion of the j would have to be somewhat long, so there would be a higher volume of air pressing down on the air in the bottom of the j. The benefits of such a design would be that you could build high shelves near the ceiling, fill the units up with ice in the morning and put them on the shelves, and then not worry about them for hours. Also, not worry about, nor hear them, when going to sleep. Well, you would hear ice melting, but that isn't as annoying to me as the ridiculous loudness of the air conditioner.