A novel solar trigeneration system integrating Photovoltaic/Thermal collectors and seawater desalination: dynamic simulation and economic assessment

This paper investigates the integration of renewable energy sources and water systems, presenting a novel solar system producing simultaneously: electrical energy, thermal energy, cooling energy and domestic water. The polygeneration system under analysis includes photovoltaic/thermal solar collectors (PVT), a multi-effect distillation (MED) system for seawater desalination, a single-stage LiBr-H2O absorption chiller and additional components, such as storage tanks, auxiliary heaters and balance of plant devices. The PVT produces simultaneously electrical energy and thermal energy, at a maximum temperature of about 100 °C. The electrical energy is delivered to the grid, whereas the thermal energy may be used for different scopes. First, the thermal energy may be used for heating purposes and/or domestic hot water production. As an alternative, the solar thermal energy can be used to drive an absorption chiller, producing chilled water for space cooling. Finally, the solar energy, in combination with the thermal energy produced by an auxiliary biomass-fired heater, may be used by the MED system to convert seawater into domestic water. The system is dynamically simulated by means of a zero-dimensional transient simulation model. The simulation model also includes detailed control strategies, for the management of the solar thermal energy and for the control of the whole system. Results show an excellent energetic performance of the system under investigation whereas the economic profitability is good only in case of public funding.