Effects of a Solar Desalination Module integrated in a Greenhouse Roof on Light Transmission and Crop Growth

In greenhouses with roof-integrated water desalination, solar transmission is reduced by an absorbing glass sheet covered by a layer of flowing water and a top glass sheet. In this study, the main objective was to analyse differences in seasonal crop yields between greenhouses with desalination and conventional roofs in arid climates. A simulation model of the thermal and optical performance of this system is detailed as well as laboratory experiments. This model was combined with a lettuce growth model. Simulation of the spectral transmission of photosynthetically active radiation (PAR), with and without water flow, was validated through laboratory experiments. A sensitivity analysis of the influence of the optical parameters on the transmission of the accumulated PAR and on crop yield for the complete solar desalination roof greenhouse are shown to give adequate representation of the relationships between light transmission and seasonal crop yield production sufficient to produce design guidelines for the desalination concept manufacturers or growers.