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• Enhancing the dielectric strength of air gaps in transmission line towers. • Application of an epoxy–polythiol coating on a cross-arm for the enhancement. • Effect of different stoichiometric ratios of polythiol on coating performance. An epoxy–polythiol coating on a cross arm is an effective method to enhance the dielectric strength of air gaps in transmission line towers and reduce the occurrence of bird-related faults. However, epoxy–polythiol dual-component raw materials could not achieve the prescribed stoichiometric ratio of 1:1, affecting the protective performance of the formed insulation layer. This study characterizes the cured systems of epoxy–polythiol with imbalance stoichiometry using Fourier-transform infrared spectroscopy and scanning electron microscopy. Tests were conducted to analyze parameters of the epoxy–polythiol curing system, including breakdown strength, cure time, thermal conductivity, water absorption rate, and mechanical properties. Results demonstrate that nonstoichiometric conditions reduce the curing time, breakdown strength, thermal conductivity, and water absorption of the epoxy–polythiol curing system. However, a slight increase in the equivalent amount of the curing agent improves the mechanical properties of the cured products. [ABSTRACT FROM AUTHOR]

Bird pest control has become a major task for the operation and maintenance of distribution network lines. Epoxy resin that cures quickly at room temperature can be used to coat locations where birds frequently build their nests. However, epoxy resin has enormous internal stress and is brittle, so it is essential to toughen it. In this paper, for a room temperature curing system composed of polyurethane-modified epoxy resin and a polythiol curing agent, three kinds of particles, i.e., Al2O3, SiO2, and Mg(OH)2, were used to modify a polyurethane modified epoxy resin. Orthogonal experiments were designed to study the effects of different fillers on the comprehensive properties of polyurethane-modified epoxy resins. The experimental results showed that there were not only independent effects of different kinds if particles on the resin, but also synergistic effects of multiple particles. Nanoparticles can reduce the defects introduced by microparticles to a certain extent and improve the mechanical and electrical properties of the resin. The overall performance of the resin was optimized when the amounts of SiO2, Al2O3, and Mg(OH)2 were 1.7%, 2.5%, and 7%, respectively. The tensile strength of the resin was increased by 70%, the elongation at a break by 67.53%, and the breakdown strength by 20.31% compared with before the addition of filler. The microscopic morphology and thermal properties of the resin before and after the addition of filler were also studied. Adding fillers caused more cracks to absorb part of the energy when the resin matrix was stressed and increased the rigidity of the resin matrix and the resin's glass transition temperature (Tg) by 13.48 °C. Still, the temperature corresponding to the maximum rate of weight loss (Tmax) remained unchanged. [ABSTRACT FROM AUTHOR]

• A novel self-cooling for concentrated PV system was proposed and validated by experiments. • The self-cooling was triggered once the cell temperature exceeds a threshold. • Solar cell temperature was reduced from 69.3 °C to 56.6 °C via self-cooling. • An arrangement of four thermoelectric modules further decreased temperature to 42.5 °C. • Self-cooling concept could be realized at relatively high irradiation intensity. Compared to flat-plate photovoltaic, concentrated photovoltaic (CPV) has advantages of lower solar cells cost and higher efficiency, but requires a sophisticated cooling system and additional energy to maintain its cooling system. In this study, a novel thermoelectric self-cooling for CPV system was proposed, which integrates thermoelectric module to provide energy for an auto-cooling scheme. The self-cooling CPV system underwent experimental validation, subsequently demonstrating its applicability across a series of numerical cases. Additionally, optimal scheme, transient response and economic performance of the self-cooling technology were discussed. The experimental results showed that temperature of solar cell was reduced from 69.3 °C to 56.6 °C after activating the self-cooling at concentration ratio of 25, irradiation intensity of 1000 W/m2 and ambient temperature of 25 °C, where the open-circuit voltage, output power and efficiency of the solar cell were respectively 2.75 V, 2.31 W and 29 %. Increasing usage of four thermoelectric modules further reduced the temperature to 42.5 °C and elevated the output power to 2.38 W. A conceptual design of 10 kW self-cooling CPV power station was carried out. The results indicated that electric load of self-cooling device could reach 3368 W at concentration ratio of 50 and irradiation intensity of 1000 W/m2, and the self-cooling concept in CPV system could be successfully realized under irradiation intensity ≥600 W/m2 and concentration ratio ≥40. The above data showed that the temperature could be reduced by 39 % through using self-cooling technology. The advantage of CPV power station integrating with thermoelectric self-cooling method over typical passive cooling illustrated the potential of the self-cooling technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • An electrostatic dust removal method for solar photovoltaic panels is investigated. • The dust removal mechanism is analyzed. • Relative humidity affects the effectiveness of dust removal. • Optimizing the metal plate type can improve the dust removal efficiency. Electrostatic dust removal has the advantages of energy saving, high efficiency, and controllability, and has become the preferred dust removal solution for solar photovoltaic (PV) panels in recent years. This paper investigates a new electrostatic adsorption dust removal method for solar PV panels based on the electrostatic dust removal effect of carbon nanotubes (CNTs) transparent conductive films. In the sheet resistance range of 500–1×105 Ω/□, the electrostatic dust removal effect of CNTs transparent conductive films has little relationship with the film sheet resistance, and when the electric field strength in the dust removal area is 6 kV/cm, the final dust removal rate of different films can reach more than 98.6 %, and the power generation efficiency of the PV panels can reach 94–97 % of that of the ordinary PV panels in the surface clean state after dust removal. The influence of the environment on the dust removal effect is mainly reflected in the relative humidity. When the relative humidity of the dust removal environment is 70 %, it shows the optimal dust removal effect, and the electric field strength required for the dust particles to jump is the lowest, which is 2.46 kV/cm. The highest dust removal efficiency can be achieved by using a metal plate with a lower surface curvature of 1/9.08 cm−1, and the final dust removal rate can reach 98.92 %. The research results are of great significance for further developing electrostatic dust removal technology in the solar PV panel dust removal field. [ABSTRACT FROM AUTHOR]