n-n Type Heterojunction Enabling Highly Efficient Carrier Separation in Inorganic Solar Cells

Carrier separation in a solar cell usually relies on the p-n junction. Here we show that n-n type inorganic semiconductor heterojunction is also able to separate the exciton for efficient solar cell applications. The n-n type heterojunction was formed by hydrothermal deposition of Sb2(S,Se)3 and thermal evaporation of Sb2Se3. We found that the n-n junction is able to enhance the carrier separation by the formation of an electric field, reduce the interfacial recombination and generate optimized band alignment. The device based on this n-n junction shows 2.89% net efficiency improvement to 7.75% when compared with the device consisted of semiconductor absorber-metal contact. The study in the n-n type solar cell is expected to bring about more versatile materials utility, new interfacial engineering strategy and fundamental findings in the photovoltaic energy conversion process.

Photovoltaic Energy Conversion Systems with Sliding Mode Control

A new sliding-mode-control-based power conversion scheme is proposed for photovoltaic energy conversion systems. The perturbation and observation (P&O) maximum power-point tracking (MPPT) approach is adopted for optimizing the power generation capabilities from solar panels. Due to the inherent nonlinear dynamics of power converters, we need to adopt a nonlinear control approach to optimize the energy conversion efficiency and tolerate the fluctuations and changes of load and sunlight irradiance. In this manuscript, novel first-and higher-order sliding mode control approaches are proposed, aiming to provide a systematic approach for the robust and optimal control of solar energy conversion, which guarantees Lyapunov stability and consistent performance in the face of external perturbations and disturbances. Moreover, to eliminate the chattering phenomenon inherent in the first-order approach, super-twisting second-order sliding mode control is developed for the buck-boost converter. Furthermore, the output of DC–DC converter supplies a voltage-oriented-control (VOC)-based space-vector pulse-width-modulated inverter to generate three-phase AC power to the grid. To demonstrate the robustness and effectiveness of the proposed scheme, computer simulations and dSPACE hardware-in-the-loop platform have been carried on for examining the proposed sliding-mode-control-based solar energy conversion system.

Comparitive Studies of Futuristic Optimisezed and Regular Solar Panels with Windload Effects on Solar Farms, Solar Panels at High Altitude for Free Green Solar Energy

Solar energy is one of the most promising green and eco-friendly renewable energy out of the wind and other non-conventional energies. In nature, we have abundance of solar energy, due to this there is a significant attention on capturing the solar energy by photovoltaic systems in recent years. Photovoltaic energy conversion is most harnessing renewable energies for different communities especially in developing countries like India. The efficiency decrease is not only due to the shadows of buildings, but also due to birds, lack of sunlight and also wind effect on solar panels which will decrease efficiency and damage the total panels or array of panels. In this work, two different analyses are carried out with changing wind velocities and angle. The aerodynamic effects on the panels were investigated by varying the orientation of panels from 0 to 180 degrees and two different wind speeds of 5m/s and 25m/s. Initial angle of 0 degrees which is normal to the flow direction is solved for two different wind speeds of 5 m/s and 25 m/s and followed by changing the orientation of panels from 0 to 180 degree inclination to investigate the aerodynamic effects on the panels. Depending on the results obtained a futuristic panel design will be proposed which can generate optimum power and also aerodynamically effective. This current study indicates that the pressure distribution on the front face of the solar panels, which are aptly suitable to design optimized solar panel shapes.