Well. In my vast experience 1 square meter of evaporator produces about 1 liter per day. On the other hand 1 square meter of solar panel makes 200 watts and you need 20 watts/liter/hour on the osmosis machine. So the panel is 10*200/20 = 100 times more "efficient", if the use of land area is the issue here (and if the sun shines 10 hours)