Simulated Research On Low Concentration Solar Photovoltaic-thermal Hybrid System Based On TRNSYS

To improve the comprehensive efficiency of using solar energy,solar photovoltaic-thermal(PVT)combined technology is one of the critical researches in the field of solar energy,which is based on solar thermal utilization and photovoltaic conversion.At present,flat PVT can produce hot water mainly concentrating in low temperature field(40~60?),which is inadequate to reach demanded temperature(85?).Besides,the thermal efficiency of plat PVT decrease apparently in high temperature field(70~95?),causing a low conversion efficiency.This work proposed a novel low solar concentrated PVT hybrid system combining the advantages of flat PVT and parabolic trough collector(PTC).This hybrid system have three parts of energy sources:flat PVT can heat the running water up to around 50?and store in thermal collection tank,achieving the goal of warm up the water;the warm water will be heated up to 85?when it flow into thermal supply tank from thermal collection tank;when the temperature of output water from thermal supply tank below 85?,assistant heater will keep output water at the temperature of 85?and maintain this temperature.This hybrid system can also produce electric power when it satisfies the demanded thermal water,PVT subsystem and PTC subsystem both work in a relatively high efficiency.Our researches and results are as follow:(1)we proposed a novel low solar concentrated PVT hybrid system.Besides,a simulated module of PV/T and PTC combined system was established based on transient system simulation software TRNSYS.Using typical weather data provided by weather display Meteonorm,electrical efficiency,thermal efficiency,and assurance rate of solar energy are our optimization objectives.This paper simulated and optimized some critical parameters like thermal collection tank volume and thermal supply tank volume,and analyzed a whole year performance on the foundation of optimal solution.From results obtained,the increase of thermal collection tank volume or thermal supply tank volume will cause the increase of assurance rate of solar energy.The thermal collection tank volume should select a large value of range,the thermal supply tank volume should consider the heat-collecting capacity of PCT when it satisfies the water demand,these can offer a reference for selecting tank volume.Under the conditions of optimal value of thermal collection tank volume 6m~3 and thermal supply tank volume 8m~3,the annual average electric efficiency and thermal efficiency of PVT can reach to 12.40%and 18.75%respectively,and annual average thermal efficiency of PTC can reach to 50.97%.The integrated utilization efficiency of solar energy can also reach to 82.13%,meanwhile,the assurance rate of solar energy is approximately 52.21%.(2)we investigated the adaptation and practicability of the system aiming at the load of public bathroom,school bathroom,and production plant in five typical cities about solar energy distribution.It indicated that this system can adapt to the area with less solar resources,with unfocused demand of water.We reached the goal of reducing the consume of assistant power and improving the integrated utilization efficiency of solar energy.