Abstract: Power generation capacity is an important indicator for the quantitative assessment of the benefits of photovoltaic（PV）units,and the loss of inverters are closely related to the power generation capacity indicators.Existing models for PV units generation capacity are excessively complex or difficult to calculate its loss accurately since the effects of converters parameters and control algorism are ignored.To address the above issues,the calculation method of PV unit generation capacity based on concentrated loss model is proposed.The method proposed adopts the concentrated equivalent model to simulate converter loss at diverse operating points in accordance with the instant output of converter.This method is simple and accurate since less parameters are needed and the calculation burden is not increased.The effects of power electronic device parameters and control on generation capacity are considered in the model.Finally,based on the RT-LAB real-time simulation platform,the annual power generation model of grid-connected PV unit is built and a comparison is made with the actual system.The simulation results prove the correctness of the model.