• Energy Research

The adaptability of maximum power point tracking (MPPT) of a solar PV system is important for integration to a microgrid. Depending on what fixed step-size the MPPT controller implements, there is an impact on settling time to reach the maximum power point (MPP) and the steady state operation for conventional tracking techniques. This paper presents experimental results of an adaptive tracking technique based on Perturb and Observe (P&O) and Incremental Conductance (IC) for standalone Photovoltaic (PV) systems under uniform irradiance and partial shading conditions. Analysis and verification of measured and MATLAB/Simulink simulation results have been carried out. The adaptive tracking technique splits the operational region of the solar PV’s power–voltage characteristic curve into four and six operational sectors to understand the MPP response and stability of the technique. By implementing more step-sizes at sector locations based on the distance of the sector from the MPP, the challenges associated with fixed step-size is improved on.The measured and simulation results clearly indicate that the proposed system tracks MPP faster and displays better steady state operation than conventional system. The proposed system’s tracking efficiency is over 10% greater than the conventional system for all techniques. The proposed system has been under partial shading condition has been and it outperforms other techniques with the GMPP achieved in 0.9 s which is better than conventional techniques.

In this paper, we present single heterojunction p-i-n GaAsSbN/GaAs solar cells grown by low-temperature liquid-phase epitaxy (LPE) – this is of interest as a component of multi-junction solar cell devices. The quaternary absorber layer was characterized by low excitation power photoluminescence to give the temperature dependence of the bandgap. This conformed to the Varshni function at low temperatures to within 10 meV, indicating relatively small alloy potential fluctuations. The absorption properties and the transport of the photogenerated carriers in the heterostructures were investigated using surface photovoltage method. A power conversion efficiency of 4.15% (AM1.5, 1000 W·m−2) was measured for p-i-n GaAsSbN/GaAs solar cells, which is comparable to the efficiency of MOCVD grown devices of this type. This is promising for the first report of LPE grown GaAsSbN/GaAs solar cells since the current record efficiency for the cells based on these compounds grown by MBE stands just at 6%. The long-wavelength photosensitivity of the cells determined from external quantum efficiency and surface photovoltage measurements was shown to be extended to 1040 nm.

This study aims to evaluate the performance of a photovoltaic module under some extreme climate conditions, and with a case study for Iraq. CFD model is developed for the analysis of the photovoltaic module using the commercial CFD software of COMSOL Multiphysics v5.3a for the transient conditions. The results are verified with the analytical solution to the one-dimensional non-linear energy balance equation using Matlab. The results are also compared with measurements reported in the literature for validation. The results reveal that the free convection currents in inclined and horizontal positions of the module were weaker relative to the vertical position. Also, the increase in the length of inclined photovoltaic module, up to 1.3 m, enhances the heat transfer rate. However, beyond this length, the temperature of the module becomes higher, and the convective heat transfer coefficients are reduced regardless of the inclination. In the horizontal position, the convective heat transfer rate is lower, particularly on the bottom surface of PV system.