The Need to Correctly and Deliberately Report “Efficiency” for Solar Water Evaporators

Solar steam generation (SSG) is a very promising strategy for seawater desalination and wastewater purification. A solar‐to‐vapor (STV) conversion efficiency is used to characterize solar water evaporators. However, the definition of STV efficiency is an approximate concept. Besides, the equation for STV efficiency is widely misused to calculate the photothermal efficiency by the community. Most seriously, too much emphasis on the STV efficiency may hinder the development of SSG technology. Thus, the community is requested to correctly and deliberately report “efficiency” for solar water evaporators.