A new coupled optical, thermal and electrical model is presented in this study and applied to a 27 concentrating photovoltaic thermal (PV/T) system for predicting the system performance under 28 various operational conditions. Firstly, a three-point-based electrical model and a method for 29 extracting its five model parameters are developed by using the currents and voltages at the short-, 30 open-circuit and maximum power points provided in usual PV module/panel datasheets. Then, the 31 model and method are validated with the existing six flat-plate PV modules and subsequently are used 32 to predict the hourly electrical performance of the CPV/T roof-top system designed by us under 33 outdoor conditions on four clear days by integrating with a scaling law developed by us. Additionally, 34 transient effect and water temperature on the storage tank are examined. It turned out that the CPV 35 system could operate for 6 hours a day with a peak instant electrical power of 50W/m2 and could 36 generate 0.22kWh/m2 electricity a day in May-July. The error in hourly electrical energy gained 37 between the predictions and observations is in a range of (3.64-8.95)% with the mean of 5.53 % in 38 four days, and the estimated water temperature in the storage tank agrees with the monitored one in 39 range of 0.2-1oC. The proposed methods as well as the electrical models could potentially be applied 40 widely across the solar energy field for the management and operation of the electrical energy 41 production from any CPV/T roof-top system
