# Indoor PV Modeling Based on the One-Diode Model
## 3 Results and Discussion
[PERSON]'s NRMSE has slowly increase to 4.935% at the same illuminance level. As [PERSON]'s method improves the existing parameter extraction technique, its associated NRMSE value is not as high as that of [PERSON]'s method. However, [PERSON]'s still involves the use of the parameter-scaling technique, which degrades at low illuminance levels. Most of the investigated methods are unable to maintain their accuracy at 100 lux. As shown in Table 6, the [PERSON] method and the proposed model generate accuracies of 5.488% and 5.513%, respectively. [PERSON]'s method also fails to maintain its accuracy on both panels, resulting in NRMSE values of 14.703% and 12.051%. In summary, the proposed model provides average NRMSE values of 2.171% and 2.691%, corresponding to a 17.149% to 19.712% improvement over [PERSON]'s method. The proposed model is able to achieve this by combining the best features of [PERSON]'s [14] translation technique and [PERSON]'s parameter extraction technique [12]. The improved accuracy of the proposed model over the compared methods highlights its importance and contribution. Figures 17-19 show the I-V curves of both panels at 1000, 800, and 600 lux under 12 W CFL illumination, respectively. The results are very similar to those presented in Figures 11-13. This is because the PV panels are illuminated by a similar level of light intensity, and the experimental range of the light spectrum has little effect on PV absorption. As the illuminance level decreases, the accuracy of these methods starts to decrease. At 400 lux, the [PERSON] method continues to undershoot the I-V curve after the short-circuit point on both panels. On the other hand, the I-V curves of the proposed model and those associated with [PERSON]'s method do not differ much from the experimental values. \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 & 0.864 & 0.718 & 0.392 \\
900 & 1.449 & 0.649 & 1.277 \\
800 & 3.007 & 3.865 & 1.455 \\
700 & 2.822 & 3.545 & 2.281 \\
600 & 2.851 & 4.031 & 2.676 \\
500 & 3.162 & 5.890 & 3.208 \\
400 & 3.682 & 7.993 & 3.312 \\
300 & 4.219 & 8.619 & 3.239 \\
200 & 4.935 & 11.170 & 3.558 \\
100 & 5.488 & 12.051 & 5.513 \\ Average & 3.248 & 5.853 & 2.691 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: NRMSE of kx0b22\(-\)04x3f with a 7 W LED. \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 & 0.948 & 0.839 & 0.753 \\
900 & 3.008 & 1.484 & 1.258 \\
800 & 2.477 & 1.853 & 1.629 \\
700 & 1.538 & 1.493 & 1.693 \\
600 & 3.869 & 1.606 & 1.242 \\
500 & 2.292 & 6.145 & 2.258 \\
400 & 2.877 & 3.922 & 2.534 \\
300 & 3.199 & 7.983 & 3.246 \\
200 & 3.578 & 11.70 Figure 19: Comparison of I–V curves obtained in different works with experimental values at 100 lux with a 12 W CFL: (**a**) kx0b22\(-\)12x1; (**b**) kx0b22\(-\)04x3f. Figure 17: Comparison of I–V curves obtained in different works with experimental values at 400 lux with a 12 W CFL: (**a**) kx0b22\(-\)12x1; (**b**) kx0b22\(-\)04x3f. At 200 lux, [PERSON]'s method results in inaccurate translation of the maximum-power voltage and open-circuit voltage, as illustrated in Figure 18. [PERSON]'s method results in a noticeable undershoot of the I-V curves near the kx0b22\(-\)12x1 panel's short-circuit point, which is also reflected by the high NRMSE. Hence, both of the I-V curves result in an undershoot compared with the experimental values. Due to the significant reduction in current at 100 lux, [PERSON]'s method struggles to accurately translate the open-circuit voltage, causing the I-V curve to be overshot after the maximum-power point. It can also be noted that the proposed model's I-V curve undershoots the experimental values, while [PERSON]'s I-V curve overshoots the maximum-power point.