When I first looked at the Desolenator, one of the 46 nominees in the INDEX awards, I was a bit dubious. We have been showing solar powered devices that worked directly with heat from the sun to vaporize water and purify it, and it seemed overly complex to throw in a solar panel and battery to boil water. When it won the People's Choice award I was more than a bit surprised.
Then I met William Janssen, the CEO of Desolenator, who came to Copenhagen to accept the award. He explained to me how it works, and there is more to this than meets the eye. Janssen explained that most of the solar stills that we have shown have a maximum output of five liters of water per day, which is not really enough for a family, whereas the Desolenator produces fifteen liters.
But more significantly, there is a real logic to the design. Solar panels are almost black and in Africa, the market for the Desolenator, they get really hot in the sun. So hot, that they deteriorate and produce less electricity. In the Desolenator, the water being purified runs over the solar panel and keeps it cool. In the process, the water is actually heated quite a bit, so that it takes far less energy to actually bring it to a boil. So there is a real logic to combining a solar panel and battery with a still: they both work better.
The unit can also provide electricity to run LED bulbs in at night, so a single unit is delivering both water and light. So perhaps I should not have been so skeptical, and the people made the right choice after all.