## 4 Conclusions  
In the past, many efforts were devoted to developing different configurations of LSC PV to increase the OE and PCE. In all cases, the monofacial solar cells from various technologies were attached to the LSC devices in order to convert the light into electricity. In the current study, a novel configuration for LSC PV was presented in various geometries and dye concentrations, with vertically placed bifacial PV solar cells made of mono c-Si. The main aim of this study was to theoretically determine the PCE of five differently configured LSC PV devices. For this purpose, the LSC PV devices with different geometries were modeled and simulated using a ray tracing software called LightTools. The lightguide was made of multiple rectangular cuboids which were mixed with organic dyes, namely Lumogen red 305 and orange 240. The emission spectra of these luminescent materials were matched to the spectral response and the quantum efficiency (QE) of \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Orange Dye**} & \multicolumn{3}{c}{**Red Dye**} \\ \hline  & \multicolumn{2}{c}{**Full Device**} & \multicolumn{2}{c}{\begin{tabular}{c} **Device with Only** \\ **Side Cells** \\ \end{tabular} } & \multicolumn{2}{c}{\
\begin{tabular}{c} **Full Device** \\ \end{tabular} } & \multicolumn{2}{c}{
\begin{tabular}{c} **Device with Only** \\ **Side Cells** \\ \end{tabular} } \\ \hline Case & Min & Max & Min & Max & Min & Max & Min & Max \\
3 & 14.53 & 15.45 & 1.75 & 2.32 & 13.12 & 15.44 & 1.71 & **2.9** \\
5 & 12.97 & **16.9** & 0.89 & 2.46 & 11.57 & 16.81 & 0.84 & 2.72 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The LSC PV efficiency of the optimal cases. Figure 8: The efficiency of the LSC PV devices as a function of the dye concentration: (**a**) the device with the cells on the edges (case 3); (**b**) the device with the cells on the back and on the edges (case 5). the bifacial solar cells. In each device, the mono c-Si bifacial solar cells were placed in between the two neighboring lightguides. To maximize the LSC PV device efficiency, the bifacial cells were also attached at the back side of the lightguides. This study has been able to demonstrate that an increase in dye concentration will lead to a lower efficiency in the devices with the bifacial cells on the back and the edges. This is because such increase in concentration results in a lower incident irradiance on the bifacial cells positioned on the back, and a higher incident irradiance on the bifacial cells placed on the sides. On the other hand, an increase in efficiency was shown when the bifacial cells were only on the edges of the collector. The results of the ray tracing simulation have indicated that the maximum efficiency was equal to 16.9% (under STC) where the dimension of the LSC PV device was \(15\times 15\) cm\({}^{2}\), consisting of nine rectangular cuboid \(5\times 5\times 1\) cm\({}^{3}\) PMMA lightguides, with Lumogen orange 240 (at 5 ppm), with 12 vertically positioned \(5\times 1\) cm\({}^{2}\) bifacial solar cells in between the lightguides and nine \(5\times 5\) cm\({}^{2}\) PV cells attached to the back of the device. However, the maximum PCE of 2.9% under STC was obtained for an LSC PV device consisting of 25 cubical \(1\times 1\times 1\) cm\({}^{3}\) PMMA lightguides, with 110 ppm red 305 dye and 40 vertically oriented bifacial PV cells of \(1\times 1\) cm\({}^{2}\) in between the lightguides. The results have demonstrated that such a concept shows promise in the commercial production of LSC PV devices with visual appeal for a built environment, for example, in facades, PV-powered vehicles, and so on. However, in reality, there are many challenges in creating such LSC PV devices based on these simulation results--for example, the electrical interconnection of the numerous bifacial solar cells is likely to be complicated. Validation, visualization, writing and editing--M.A. ; Investigation, simulation and visualization--M.N.