Mathematical power-generation model of a four-terminal partial concentrator photovoltaic module for optimal sun-tracking strategy

High-efficiency solar energy is an emerging technology which can reduce greenhouse gas emissions. A four-terminal (4T) partial concentrator photovoltaic (CPV⁺) is a promising hybrid concept to maximize the electricity yield by integrating existing photovoltaic technologies. This paper describes the mathematical modeling of a 4T CPV⁺ module for sun-tracking control optimization. The CPV⁺ module consists of low-cost auxiliary solar cells placed around the concentrator multijunction solar cells. We derived a mathematical model to predict the generated power of the 4T CPV⁺ module that incorporates inclination angle of array, location, date/time, lens optical efficiency, and solar irradiance data. The simulation revealed that the 4T CPV⁺ module with mono-facial auxiliary solar cells should always face toward the sun, similar to the conventional CPV modules, regardless of irradiance conditions. The short-term outdoor experiment using a prototype module validated the mathematical model and stayed within the margin error for generated power-per-unit module area (∼14 W/m²). The derived model will be fundamental for enhanced modeling and design optimization of the 4T CPV⁺ module.