## 4 Conclusions  
This study focused on the application of using integrated photovoltaic solar panels in light shelves to decrease the lighting energy requirement for office buildings and proposed a prototype of a modular unit composed of a light shelf combined with photovoltaic technology (LSPV) for deep office buildings in hot desert-like climatic conditions. In order to optimize the daylighting performance, three phases were carried out before the PV was attached to the LS to determine the appropriate height, reflector characteristics, and curved internal LS. The key findings of this study are specified below:  
* The optimal height for a flat LS for enhancing WPI and the uniformity index determined in this study is 1.3 m above the floor with widths of 1.1 m and 0.7 m for the external and internal LS respectively, Configuration LS3H3 is challenging to use in high rise buildings. * The use of a reflector with constant width of 30 cm at the top of the window, combined with external and internal LS configurations, is considered a good daylight strategy to improve the WPI in the back area of the model by 10%. * The optimal specification for a flat external LS, combined with a curved internal LS, for improving daylighting distribution was found to be 10\({}^{\circ}\), which increased the back daylight area by up to 5-11% at the summer and winter solstices, and less than 4% at the spring equinox. * All LS configurations are observed to provide less daylight in the back daylight area compared to the reference model; however, there is uniformity of illumination. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \begin{tabular}{c} **Configuration of** \\ **LS with PV** \\ \end{tabular}  & \begin{tabular}{c} **Lighting Energy** \\ **Consumption (kWh)** \\ \end{tabular}  & \begin{tabular}{c} **PV Energy** \\ **Production (kWh)** \\ \end{tabular}  & \begin{tabular}{c} **Net Energy Saving (kWh)** \\ **with PV Light Shelves** \\ \end{tabular}  \\ \hline \hline \begin{tabular}{c} **Reference model** \\ **LSPV1** \\ \end{tabular}  & 71.8 & 626 & 554 & 89\% \\ \begin{tabular}{c} **LSPV2** \\ **LSPV3** \\ **LSPV4** \\ **LSPV5** \\ **LSPV6** \\ **LSPV7** \\ **LSPV8** \\ **LSPV8** \\ \end{tabular}  & \begin{tabular}{c} **102.9** \\ **469** \\ **479** \\ **49.8** \\ **514** \\ **49.7** \\ **313** \\ **343** \\ **156** \\ **171** \\ \end{tabular}  & \begin{tabular}{c} **20.6** \\ **554** \\ **469** \\ **479** \\ **420** \\ **263** \\ **263** \\ **289** \\ **103** \\ **108** \\ **108** \\ **108** \\ \end{tabular}  & \begin{tabular}{c} **20.6** \\ **99** \\ **89** \\ **89** \\ **89** \\ **89** \\ **89** \\ **63** \\ **63** \\ \end{tabular}  & \begin{tabular}{c} **20.6** \\ **626** \\ **686** \\ **469** \\ **514** \\ **514** \\ **313** \\ **313** \\ **343** \\ **343** \\ **343** \\ **156** \\ **171** \\ \end{tabular}  & \begin{tabular}{c} **20.6** \\ **554** \\ **419** \\ **420** \\ **263** \\ **263** \\ **289** \\ **103** \\ **108** \\ **108** \\ **108** \\ **108** \\ \end{tabular}  & \ \begin{tabular}{c} **20.6** \\ **99** \\ **89** \\ **89** \\ **89** \\ **89** \\ **89** \\ **89** \\ **84** \\ **66** \\ **63** \\ \end{tabular}  &
\begin{tabular}{c} **20.6** \\ **99* The integration of LSPV with a conversion efficiency of only 10% can completely compensate for the lighting-specific energy consumption in all LSPV configurations. At the same time, these configurations eliminate the discomfort caused due to glare, especially during the winter season. Also, LSPV1 with a flat and 30\({}^{\circ}\) tilt angle with 100% coverage shows a higher uniformity of illumination compared to a light shelf without a solar module. * The optimal modular units of the LSPV that can achieve significantly greater savings and uniformity index within the office perimeter, close to the windows and the middle, along with the back area, are LSPV1 and LSPV2, as specified in Appendix D.  
The focus of this study is limited to the energy required for lighting and daylight distribution for visual comfort.