On the Performance of Solar Cells/Panels and Li-Ion Batteries: Simplified Models Developed at the IDR/UPM Institute

Abstract

The most relevant results from the IDR/UPM Institute research on solar cells/panels and Li-ion batteries performance are reviewed in this paper. The aim of this work is to present the possibilities of the mathematical procedures developed for space applications, with a view to extend their use to other industrial sectors. The research at the IDR/UPM Institute has been driven by selecting simple tools and procedures to model the behavior of solar cell/panel, since modeling these photovoltaic devices is normally carried out by 1-Diode/2-Resistor equivalent circuit models, which might represent an unaffordable mathematical challenge for many professionals and technicians in the renewable energy field. Concerning Li-ion batteries, the large experience accumulated during the maintenance of the UPMSat-2 battery resulted in the successful development of new mathematical models to study the performance of batteries. The models developed are based on the amount of discharged energy, measured in W•h, instead of other more traditional parameters such as the State Of Charge (SOC), measured in A•h.

Design, Ground Testing and On-Orbit Performance of a Sun Sensor Based on COTS Photodiodes for the UPMSat-2 Satellite

“…Among them, the 1-Diode/2-Resistor equivalent circuit model was selected, see Figure 6B. It is basically composed of a current source connected in parallel with a diode, together with a shunt resistance R sh , and a series resistance R s [16][17][18][19]. Using the Shockley model for the diode, the output current, I, and the output voltage, V, at the terminals of the photodiode are related implicitly by the following equation:…”

“…Among them, the 1-Diode/2-Resistor equivalent circuit model was selected, see Figure 6 B. It is basically composed of a current source connected in parallel with a diode, together with a shunt resistance R sh , and a series resistance R s [ 16 , 17 , 18 , 19 ]. Using the Shockley model for the diode, the output current, I , and the output voltage, V , at the terminals of the photodiode are related implicitly by the following equation: where I pv is the photovoltaic current, I 0 is the reverse saturation current of the diode, a is the ideality factor, R sh is the shunt resistor, R s is the series resistor, and V T is the thermal voltage of the diode, which is expressed in terms of the temperature, T , the Boltzmann’s constant, κ , and the electron charge q as: …”

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“…• Simulation of the behavior of a solar panel as a function of its operating point, radiation, and temperature. • Simulation and analysis of the behavior of a battery, applying the models developed at the IDR/UPM Institute (Pindado et al 2021b).…”

On the modeling and simulation of a stratospheric experiment power subsystem

“…In this project, based on the expertise of the IDR/UPM Institute in this field [15][16][17][18][19][20][21][22][23][24], a numerical simulator of the EPS of TASEC-Lab has been modeled to predict its performance (i.e., battery voltage and power dissipation) during operation. For this purpose, several laboratory tests have been conducted and a set of experimental data has been used to develop analytical models of the main electrical parts: a Li-ion battery and two DC-DC converters.…”

“…The test data were used to formulate a new equivalent circuit model (see Figure 4) for the characterization of the discharging battery performance. This model is based on the energy discharge level model developed at the IDR/UPM Institute [19,27]. In that model, three important assumptions are made: 1) internal energy losses (excluding joule losses) are neglected, 2) internal resistance is constant, 3) temperature and aging (cycling) effects are not considered.…”