Recently, extensive R&D has been conducted, both by industry and academia, to significantly raise the conversion efficiency of commercial photovoltaic (PV) modules. The installation of PV systems aimed at optimizing solar energy yield is primarily dictated by its geographic location and installation design to maximize solar exposure. However, even when these characteristics have been addressed appropriately, there are other factors that adversely affect the performance of PV systems, namely the temperature-induced voltage decrease leading to a PV power loss and the dust accumulation (soiling). The latter is the lesser acknowledged factor that significantly influences the performance of PV installations especially in the Middle East region. In this paper we report on the investigation of the structural and physical properties of the desert-dust particles in the State of Qatar. The dust particles were collected directly from the PV panels installed in desert environment and characterized by different techniques, including scanning electron, optical and atomic force microscopies, X-ray diffraction, energy-dispersive, UV-Vis, micro-Raman and Fourier transform infrared spectroscopy. The vibrating sample magnetometry analyses were also conducted to study the magnetic properties of the dust particles. The influence of the dust accumulation on the PV panel performance was also presented and discussed.

In this paper, we report the evolution of silicon heterojunction solar cell properties focusing, in particular, on the indium tin oxide (ITO) layers upon consecutive thermal annealing. We find that the charge carrier density $N_{\rm e}$ of the ITO increases with higher thermal budget, while the carrier mobility remains constant. For the solar cells, their series resistance at the maximum power point $R_{\rm S}^{\rm MPP}$ first decreases due to the reduction of the ITO’s sheet resistance. With further annealing, $R_{\rm S}^{\rm MPP}$ increases again. As all monitored $R_{\rm S}$ components decrease, we attribute this to an increase of the contact resistance. The implied $V_{\text{OC}}$ and the implied fill factor both slightly degrade for annealing temperatures above 190 °C for our layers. This, as well as the change in $N_{\rm e}$ of the ITO, must be carefully considered when optimizing the thermal budget needed, e.g., for sputter damage or screen-printing paste curing.

Atomic layer deposited zinc nickel oxide (ZNO, Zn_xNi_1−xO) films with Zn concentrations of 0.09, 0.46, and 0.62 are investigated for application as a hole-selective contact for crystalline silicon solar cells. The ZNO films were found to be p-type by evaluating their contact performance on p-Si. A direct contact between ZNO and p-Si showed perfect ohmic behaviour. Spectroscopic ellipsometry measurements revealed a high optical transparency of the ZNO films with a bandgap of >3 eV. X-ray photoelectron spectroscopy confirmed a much lower valence band offset between ZNO and p-Si than the conduction band offset, which is favourable for selective hole extraction on p-Si. In addition, subsequent annealing at 200 °C significantly decreased the contact resistivity, and annealing temperatures up to 500 °C did not degrade its contact performance. A minimal contact resistivity of 21.5 mΩ·cm² was obtained on p-type c-Si for a 3.4 nm ZNO film with a Zn concentration of 0.62 after annealing at 200 °C. These results demonstrate the advantages of Zn_xNi_1−xO as a hole-selective contact for crystalline p-Si solar cells.