You know, the fridge puts out more heat to freeze the jug of water than the amount of heat this thing will remove? Moving energy isn’t free; you’re just paying to move it from the fridge to the other room. Maybe he uses mom and dad’s fridge! So even with the solar supply, it’s very inefficient. Kinda defeats the purpose.
Oh, and cutting hard plastic like that with an open knife while sitting in shorts??? Yeah, that’s safe. Knives slip off of that stuff all the time.