Modern solar cells, which use energy from light to generate electrons and holes that are then transported out of semiconducting materials and into external circuits for human use, have existed in one form or another for over 60 years. Little attention has been paid, however, to the promise of using light to drive another electricity-generating process—the transport of oppositely charged protons and hydroxides obtained by dissociating water molecules. Researchers in America report such a design, which has promising application in producing electricity to turn brackish water drinkable, on November 15 in the journal Joule.