I've used the solar camping showers and have found them quite nice when car camping in Idaho, Montana and Wyoming -- however they are useless on a cloudy day. If the sun is out, the 20L actually gets pretty hot (in the summer) and is good for about 2 showers if you conserve water. In the winter or in an area where clouds prevail, I don't know if they would be worth the effort. The versions I used were clear on one side and black plastic on the other.