Hybrid Solar Simulator for Long-Term Testing of Photothermal Materials

Solar simulators are predominantly used for testing photovoltaic devices, which usually require a relatively shorter duration of exposure. Novel photothermal materials used for interfacial solar vapor generation utilizing the principle of heat localization; on the other hand, require a relatively much longer period of exposure and testing. This necessitates excellent stability for longer timescales, in addition to good spectrum distribution match and spatial uniformity of solar simulators. A hybrid light-emitting diode (LED)–halogen (HAL) light source configuration for a solar simulator is proposed here which meets these requirements. An LED module (phosphor coated blue LEDs, 100 W) producing warm white light is used as the primary light source, in conjunction with two commercially available HAL lamps (50 W). The luminaire module performance in terms of spectrum distribution, intensity, effect of thermal management, interaction with neutral density (ND) filters, and collimating lenses is investigated under different operating configurations. The assembled solar simulator is characterized based on spectrum distribution match, temporal instability, and spatial nonuniformity against global standards. Subsequently, an easily replicable photothermal fabric configuration is performance tested under the optimized solar simulator configuration, to evaluate its efficacy in terms of solar-to-vapor generation efficiency. The usefulness of the hybrid solar simulator system is established for long-term testing as per the global standards.