Feasibility analysis of a CPV system sized by means of a TJ cell black-box model and applied to a livestock farm welding
In the Concentrating Photovoltaic (CPV) systems, the Triple-Junction (TJ) cell electrical power is separately evaluated as function of its temperature or of the solar concentration factor (C), but generally not simultaneously as a function of both variables. Because all these variables are difficult to link by means of a white-box model, a mathematical model of the black-box type based on experimental data, is defined in this paper in order to link directly the TJ cell electric power together with Direct Normal Irradiance (DNI) and TJ cell temperature at different values of C. The knowledge of a link among TJ cell electric power, DNI and TJ cell temperature is basic to evaluate the real performances of a CPV system when it has to be sized, adopting a modular configuration, to meet the energy demands of a user. Hence, the feasibility of a CPV system adopted for an agricultural livestock farm located in Salerno (Italy), is evaluated by means of the model. The main activity of the farm is the breeding of cattle and sheep for milk production; the farm is made up of a stable and a farmhouse. The optimal number of TJ cells is defined to maximize the profitability of the investment, expressed in terms of Net Present Value. A CPV plant made up of 3000 cells, with an electric peak power of 6.6 kW, allows to maximize the NPV value up to about 16 k€.