Analysis of the Thermal Stress for Combined Electrode of Soldered Crystalline Silicon Solar Cells under Temperature Field

Based on the theory of material mechanics and thermal stress analysis, the stress distribution of combined electrode for crystalline silicon solar module was studied for the first time. The shear stress and normal stress distribution of soldered structure for crystalline silicon solar cells under the thermal field were discussed. And the results show that the stress distribution is not simply linear relationship as some results found. But there is a stress concentration at the edge, which was considered as the true reason that caused microcracks at the edge of soldered solar cells. The conclusions we got in this paper provide a theoretical basis for deceasing the breakage rates of soldered crystalline silicon solar cells and improving the reliability of crystalline silicon solar modules

Interdigitated Back‐Contacted Carbon Nanotube–Silicon Solar Cells

Carbon/silicon heterojunctions provide a new perspective for silicon solar cells and in particular those made from carbon nanotubes (CNTs) have already achieved industrial-level power conversion efficiency and device size when using organic passivation and a back-junction design. However, the current state of the art device geometry for silicon photovoltaics is the interdigitated back contact (IBC) cell and this has yet to be demonstrated for CNT/Si solar cells due to the complexity of fabricating the required patterns. Herein, IBC-CNT solar cells are demonstrated via the simple spin coating of a conductive hole-selective passivating film and the evaporation of buried silicon oxide/magnesium electron-selective contacts for both polarities. The CNT coverage area fraction (fCNT) and the gap between the two polarities are optimized to minimize electrical shading loss and ensure high photocarrier collection. Large-area (4.76 cm2) highly efficient (17.53%) IBC-CNT solar cells with a Voc of 651 mV and Jsc of 40.56 mA cm−2 are demonstrated and are prepared with one alignment step for the CNT/Si contact, and photolithographic-free and room-temperature processes. These performance parameters are among the best for solution-processed dopant-free IBC schemes and indicate the feasibility of using low-dimensional carbon materials in IBC solar cells

Power Degradation Caused by Snail Trails in Urban Photovoltaic Energy Systems

AbstractIn recent years, a discoloration defect called as the snail trials emerged on crystalline silicon solar module in urban photovoltaic energy systems. It resulted in power degradation, and caused a serious concern about effects of this phenomenon on crystalline silicon solar modules, but very few publications have dealt with this phenomenon. In this paper, the crystalline silicon solar modules with snail trials are investigated by I-V and P-V characteristics, electroluminescence (EL) technique, thermography analysis, and energy production in photovoltaic power plant. The obtained results show that the snail trails may affect output of power for crystalline silicon solar modules compared with reference module, the energy production measured was about 9.1% lower than the normal array

Application of eco-compensation to control transboundary water pollution in water diversion projects: The case of the Heihe River transfer project in China

Controlling transboundary water pollution is particularly crucial for the sustainable development of diversion basins, while eco-compensation is an essential incentive for multistakeholder transboundary water pollution control. Considering the dynamics of the various actors' pollution control behavior in the Heihe River water transfer project and utilizing differential game theory, we construct a baseline strategy, a horizontal eco-compensation strategy, and an incentive coordination strategy under scenarios with and without authority incentives. The corresponding equilibrium solutions are then determined, and comparisons are made between the payoffs of the players in the six different structures, thus defining the optimal scenario for the different programs. In the case of the largest ecological water transfer project of the Heihe River in Northwest China, according to the research findings, (1) when eco-compensation is funded through a single source, incentive coordination scenarios can contribute effectively to water pollution control instituted by the main participants in water diversion projects; when multiple financing sources are available, horizontal ecological compensation scenarios are more compatible with the individual interests of local municipalities to improve the water quality environment. (2) Water-receiving cities voluntarily eco-compensate for water-supplying cities, and this incentive structure for eco-compensation facilitates a significant improvement in the effectiveness of water pollution control and therefore the harmonious promotion of sustainable economic and environmental development in eco-fragile areas. (3) Water transfer projects, for which the two participants are at widely.different levels of development and the environment is inherently fragile, can facilitate, via an eco-compensation mechanism that combines horizontal and vertical scenarios, sustainable development-oriented policies for eco-compensation systems in which the authority participates as a third-party game player. The research supports the establishment of policies for the governance of the transboundary water diversion project basins to address conflicts in water pollution management

Interdigitated Back‐Contacted Carbon Nanotube–Silicon Solar Cells

Carbon/silicon heterojunctions provide a new perspective for silicon solar cells and in particular those made from carbon nanotubes (CNTs) have already achieved industrial‐level power conversion efficiency and device size when using organic passivation and a back‐junction design. However, the current state of the art device geometry for silicon photovoltaics is the interdigitated back contact (IBC) cell and this has yet to be demonstrated for CNT/Si solar cells due to the complexity of fabricating the required patterns. Herein, IBC‐CNT solar cells are demonstrated via the simple spin coating of a conductive hole‐selective passivating film and the evaporation of buried silicon oxide/magnesium electron‐selective contacts for both polarities. The CNT coverage area fraction (fCNT) and the gap between the two polarities are optimized to minimize electrical shading loss and ensure high photocarrier collection. Large‐area (4.76 cm2) highly efficient (17.53%) IBC‐CNT solar cells with a Voc of 651 mV and Jsc of 40.56 mA cm−2 are demonstrated and are prepared with one alignment step for the CNT/Si contact, and photolithographic‐free and room‐temperature processes. These performance parameters are among the best for solution‐processed dopant‐free IBC schemes and indicate the feasibility of using low‐dimensional carbon materials in IBC solar cells

Stable Organic Passivated Carbon Nanotube–Silicon Solar Cells with an Efficiency of 22%

The organic passivated carbon nanotube (CNT)/silicon (Si) solar cell is a new type of low-cost, high-efficiency solar cell, with challenges concerning the stability of the organic layer used for passivation. In this work, the stability of the organic layer is studied with respect to the internal and external (humidity) water content and additionally long-term stability for low moisture environments. It is found that the organic passivated CNT/Si complex interface is not stable, despite both the organic passivation layer and CNTs being stable on their own and is due to the CNTs providing an additional path for water molecules to the interface. With the use of a simple encapsulation, a record power conversion efficiency of 22% is achieved and a stable photovoltaic performance is demonstrated. This work provides a new direction for the development of high-performance/low-cost photovoltaics in the future and will stimulate the use of nanotubes materials for solar cells applications

Organic Passivation of Deep Defects in Cu(In,Ga)Se2 Film for Geometry-Simplified Compound Solar Cells

Diverse defects in copper indium gallium diselenide solar cells cause nonradiative recombination losses and impair device performance. Here, an organic passivation scheme for surface and grain boundary defects is reported, which employs an organic passivation agent to infiltrate the copper indium gallium diselenide thin films. A transparent conductive passivating (TCP) film is then developed by incorporating metal nanowires into the organic polymer and used in solar cells. The TCP films have a transmittance of more than 90% in the visible and nearinfrared spectra and a sheet resistance of ~10.5 Ω/sq. This leads to improvements in the open-circuit voltage and the efficiency of the organic passivated solar cells compared with control cells and paves the way for novel approaches to copper indium gallium diselenide defect passivation and possibly other compound solar cells