# Indoor PV Modeling Based on the One-Diode Model
## 1 Introduction  
Renewable energy sources have become an urgent priority as a result of climate change and the fact that a major portion of the energy consumed globally is still generated from fossil fuels [1]. Solar and ambient light are the most promising renewable energy sources, and photovoltaic (PV) panels allow for the most direct conversion of light energy to electrical energy. As a result, photovoltaic technology has attracted extensive interest over the last few decades. PV panels have a wide range of applications, ranging from high-power industrial energy generation to low-power emerging energy harvesting to power Internet of Things (IoT) devices. PV panels are also expected to enable the most economical renewable energy in the near future due to their low and decreasing manufacturing costs [2]. A PV panel is made up of silicon wafer cells that can be connected in series or in parallel to generate the desired voltage and current [3]. The performance of PV panels can be easily determined using the I-V curve. This curve represents the relationship between the output current and the voltage of the PV panel. The equivalent circuit-based models are most commonly used to describe the curve [4]. However, the curve is nonlinear and highly dependent on both irradiance/illuminance levels and temperature. As a result, the complexity of developing an accurate model is high. Nonetheless, an accurate PV model is critical for evaluating the electrical response of different PV panels under a variety of operating conditions that can be encountered in practice. PV models employ an equivalent circuit with a few parameters that adequately reflect its behavior, and they can be calculated either through optimization or analytical methods. Optimization methods were employed to extract the parameters in [5; 6; 7; 8; 9]. However, the accuracy of the extracted parameters is highly dependent on the algorithm type, objective, and initial settings. With an increase in the number of factors, the optimizer's ability to produce accurate results decreases. Additionally, optimization methods require I-V curve information to determine an optimal match. This may restrict the model's applicability, as not all panel manufacturers provide information on the I-V curve. A few analytical works have involved the extraction of the model's parameters solely from datasheet values. Since almost all manufacturers provide datasheet values, the analytical method can be applied to nearly all PV panels. However, the models only work well at the standard irradiance of 1000 W/m\({}^{2}\). Therefore, considering that environmental conditions such as irradiance levels might affect the model's parameters, the studies reported in [10; 11; 12; 13] were conducted using the parameter-scaling technique. The results show significant performance variations with several commercial PV panels at varying irradiance/illuminance levels. Hence, the findings suggest that parameter scaling should not be seen as the primary technique for modeling PV behavior. In [14; 15; 16; 17; 18], the characteristic point translation technique was used. This technique can translate three characteristic points from the data sheet to other irradiance levels: short-circuit current, open-circuit voltage, and maximum-power points. However, the accuracy of this characteristic point translation technique can still be improved at low irradiance levels. Moreover, the limited amount of research conducted using the characteristic point translation technique in indoor environments highlights a knowledge deficit with respect to the performance of typical PV models. This deficit constrains our capability to estimate the operation of PV panels and their output power under indoor artificial light. An overview of PV modeling methods is shown in Figure 1.  
The main objective of this work is to develop a PV model with the characteristics of high accuracy in indoor conditions and wide applicability, only requiring characteristic points at a reference illumination.