# Indoor PV Modeling Based on the One-Diode Model
## 4 Conclusions  
The use of PV panels to convert light into electricity in indoor environments is expected to increase significantly in tandem with the rapid deployment of low-power IoT sensor devices. Hence, an accurate model is required to evaluate and predict the performance of PV panels. However, the nonlinear characteristics of PV panels make the modeling of their electrical response a challenging task. In this paper, we present a one-diode PV model with two resistors with improved characteristic point translation and parameter extraction techniques for indoor PV modeling. This model only requires one set of reference values, such as those at 1000 lux, to predict the electrical behavior of PV panels under different illuminance levels, which enables its wide applicability. Two PV panels were used and illuminated under different types of commonly employed light technologies. The model was tested, and its results were compared to those reported in other works using parameter-scaling and translation techniques, in addition to comparison with experimental values. The results show that the proposed model's accuracy is higher than that of the compared methods and close to the experimental values. Furthermore, the proposed model is able to provide an average accuracy improvement of 15.75% over the compared methods. Therefore, the proposed model, which can provide consistently high accuracy in modeling PV behavior at various illuminance levels for different light and PV technologies, can contribute to the explosive growth in the development of new energy for sustainable indoor IoT applications.  
There are many interesting possible directions for future work. First, the investigation of the effects of temperature and its modeling is an exciting proposition that can extend the model's applicability. Secondly, how the angle between the light source and the PV panel affects the performance of the latter is another worthwhile direction for future research. Lastly, the extension of the model to other light sources and emerging PV technologies, especially for indoor applications, will be studied in the future.  
Conceptualization, C.J.Q.T. and M.D.; methodology, C.J.Q.T. and M.D.; validation, M.D. and R.A.; formal analysis, C.J.Q.T. and M.D.; investigation, C.J.Q.T.; resources, K.N.M.H.; writing--original draft preparation, C.J.Q.T.; writing--review and editing, M.D., K.N.M.H., A.L.S., and R.A.; visualization, A.L.S.; supervision, M.D.; funding acquisition, K.N.M.H. All authors have read and agreed to the published version of the manuscript.  
This research was funded (APC) by Yayasan Universiti Teknologi PETRONAS YUTP-FRG 1/2021: 015 LC0-349.  
Data Availability Statement: Data are contained within the article.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Illuminance Level (lux)**} & \multicolumn{3}{c}{**NRMSE (\%)**} \\ \cline{2-4}  & **[PERSON]** & **[PERSON]** & **Proposed** \\ \hline
1000 & 0.974 & 0.973 & 0.346 \\
900 & 1.675 & 1.169 & 1.129 \\
800 & 2.178 & 2.966 & 1.340 \\
700 & 3.223 & 3.571 & 2.685 \\
600 & 3.138 & 3.778 & 2.914 \\
500 & 3.265 & 5.128 & 3.566 \\
400 & 3.293 & 7.488 & 3.423 \\
300 & 4.666 & 9.005 & 4.717 \\
200 & 4.363 & 11.214 & 4.179 \\
100 & 6.070 & 12.465 & 4.269 \\ Average & 3.285 & 5.776 & 2.857 \\ \hline \hline \end{tabular}
\end{table}
Table 8: NRMSE of kx0b22\(-\)04x3f with a 12 W CFL.  
**Acknowledgments:** The authors gratefully acknowledge the support of this research from Universiti Teknologi PETRONAS.  
**Conflicts of Interest:** The authors declare no conflict of interest.