# Indoor PV Modeling Based on the One-Diode Model
## 3 Results and Discussion
A similar situation also occurs at 600 lux, where the I-V curves for the kx0b22\(-\)04x3f panel differ, although still acceptable. However, [PERSON] reported a slight overshoot after the maximum-power point for the kx0b22\(-\)12x1 panel. Figure 14: Comparison of I–V curves obtained in different works with experimental values at 400 lux with a 7 W LED: (**a**) kx0b22\(-\)12 xl; (**b**) kx0b22\(-\)04x3f. Figure 15: Comparison of I–V curves obtained in different works with experimental values at 200 lux with a 7 W LED: (**a**) kx0b22\(-\)12 xl; (**b**) kx0b22\(-\)04x3f. At 400 lux, [PERSON] overshot the I-V curve after the maximum-power point on both panels, with an additional undershoot before the maximum power point. On the other hand, the proposed model and [PERSON]'s I-V curves do not differ much from the experimental values. Additionally, it can be clearly seen that [PERSON]'s inaccurate translation of open-circuit voltage results in an undershoot for the kx0b22\(-\)04x3f panel's I-V curve. [PERSON] also encountered difficulties in translating the open-circuit voltage and maximum power voltage at 200 lux, as illustrated in Figure 15. Both of the I-V curves undershoot when compared to the experimental values. There is also a noticeable undershoot for [PERSON] and the proposed model's I-V curve near the kx0b22\(-\)04x3f panel's short-circuit point. Due to the significant reduction in current at 100 lux, [PERSON] struggled to accurately translate the open-circuit voltage, causing the I-V curve to overshoot 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. Nevertheless, it remains within the acceptable range. The results for the two PV panels (kx0b22\(-\)12x1 and kx0b22\(-\)04x3f) illuminated with a 7 W LED light source are presented in Tables 5 and 6. At 1000 lux, the results of the discussed works fit very closely to the experimental values, resulting in a low NRMSE. However, the results indicate that as the illuminance level decreases, the NRMSE of both panels increases using all investigated methods. [PERSON]'s NRMSE at 900 lux is 3.008%, which is slightly higher than that achieved with the other methods, while at 800 lux, Table 6 shows that [PERSON] and [PERSON]'s methods generated NRMSE values of 3.007% and 3.865%, respectively. Both results are more than two times that achieved with the proposed model (1.455%). The NRMSE does not vary considerably between the investigated methods at 700 and 600 lux. However, the proposed model's accuracy begins to outperform the other methods starting at 500 lux. At this level, [PERSON]'s method generates an NRMSE of 6.145% (Table 5). This is due to the use of iterative thermal voltage to translate the open-circuit voltage. The iterative process is unable to provide an accurate fit for low-wattage panels with a low number of PV cells. As the thermal voltage is used in the subsequent translation, it affects the model's accuracy. In comparison, the proposed model provides a significantly lower NRMSE of 2.258%. This is because the proposed translated open-circuit voltage is derived from the relationship between light and voltage using all three characteristic points. Hence, the model's accuracy can be improved. [PERSON]'s method also encounters difficulties in accurately modeling the maximum-power voltage at 400 and 300 lux, resulting in NRMSE values of 7.993% and 8.619%, respectively. Although [PERSON]'s initial series resistor serves to represent PV losses under outdoor conditions, the assumption of an infinite value of \(R_{p}\) in the derivation affects its accuracy considerably under indoor conditions. It can be seen that  
Figure 16: Comparison of I-V curves obtained in different works with experimental values at 100 lux with a 7 W LED: (a) kx0b22\(-\)12x1; (b) kx0b22\(-\)04x3f. at 200 lux, [PERSON]'s NRMSE values are significantly higher for both panels (11.709% and 11.170%) due to inaccurate translation.