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High‐flux solar simulator (HFSS) commonly serves as a vital instrument for conducting material testing and thermochemical experiments, offering valuable applications in the fields of photovoltaic cells and concentrated solar energy. This paper proposes a continuously adjustable HFSS based on light‐emitting diodes (LEDs), which can be employed for experimental testing in the solar cell aging. First, an irradiation unit module has been built using high‐power LEDs and total internal reflection lenses, and the irradiation performance of the single unit has been validated. In theory, a dome layout model is proposed, in which a detailed geometric analysis is provided for the maximum number of units that can be accommodated on the dome, considering unit size and dome dimensions. Subsequently, aluminum disc has been used as thermal flux sensors, and the irradiation distribution of the system is characterized using a charge‐coupled device observation camera and Lambertian board. The results indicate that the system offers an adjustable average flux ranging from 1.6 to 9.04 kW/m2 when the system input current is in the range of 7.2–54 A. Additionally, the system demonstrates a spatial nonuniformity of 2% within a 10‐mm diameter (Φ = 10 mm) region test region and temporal instability of 2% within 30 min. A radiation unit with an LED–TIR structure is designed, and a high‐density spherical cap layout model is proposed to optimize its distribution. On the basis of this design, an adjustable high‐flux solar simulator is constructed.

High‑spectral‑fidelity solar simulators are indispensable for rigorous photovoltaic characterization, as they provide stable, reproducible irradiance that closely conforms to the AM 1.5G reference spectrum. The latest IEC 60904‑9:2020 standard imposes stringent limits on spectral mismatch (SM), coverage, and deviation, driving the need for innovative design strategies. This work introduces a data‑driven LED spectrum reconstruction methodology to engineer a Class A+ LED Solar Simulator (LSS) spectrum. Manufacturer‑provided spectral profiles spanning 300–1200 nm were digitized using a precision plot‑digitization tool and calibrated via a Spectral Mismatch Calculator to ensure wavelength alignment and intensity normalization. Custom numerical optimization algorithms then refined these datasets to compute the optimal mixing ratios of broadband phosphor‑converted white LEDs (400–900 nm), combined with targeted UV, visible, and NIR emitters. The finalized 13‑LED configuration achieved a Spectral Coverage (SPC) of 99.52% and a Spectral Deviation (SPD) of 17.42%, exceeding the Class A+ acceptance criteria while employing a minimal component count. Although minor uncertainties may originate from the digitization process, such as image resolution and axis calibration, these can be effectively mitigated by integrating direct numerical spectra supplied by manufacturers. This approach establishes an efficient, high‑accuracy framework for LSS spectral design. Future work will advance to hardware prototyping and empirical validation of the simulator’s irradiance spectrum under real‑world operating conditions, fully compliant with IEC 60904‑9:2020.

Solar simulators have been widely used to characterize the performance of solar photovoltaics cells, which typically have a size of 156 × 156 mm2. In order to amplify the testing area, a flexible optimal design method for solar simulators is presented in this study. In this work, 20 quartz tungsten halogen lamps are used with a light filter composed of a mixture of distilled water and cyan ink. The methodology includes the measurements of the irradiance nonuniformities, spectral profile, and explores the effects of light filters on the primary light source used. During this stage, the power source of the lights should be selected, where direct current is usually assumed. As soon as the primary light source is characterized by its corresponding model, a layout is defined by optimizing the nonuniformity of the irradiance. The constructed solar simulator presents a spectral match of 1.69%, a spatial nonuniformity of irradiance of 1.66%, and a temporal instability of irradiance lower than 0.1%. In addition, the current‐voltage curves are compared under indoor and outdoor test showing a root‐mean‐squared error lower than 3%. A class CAA solar simulator is achieved according to the International Electrotechnical Commission and American Society for Testing and Materials standards over an area of 270 × 270 mm2, suitable for testing small size solar photovoltaic modules. A solar simulator based on quartz and tungsten is designed, incorporating a filter composed of a mixture of distilled water and cyan ink. Methodology aspects of design are addressed, considering a characterization of the primary light source to the solar simulator. Proposed solar simulator achieved a Class A in the irradiance non‐uniformity, according to the IEC and ASTM standards.

The article describes a large scale of rectangular light source design comprised of six different types of high-power light emitting diodes (LEDs). The new modular based on the LED solar simulator with the greatest size using the symmetrical LED positioning method. The experiment provided the irradiation of the solar simulator in the class AAA over 416 cm2. The rectangular LED module illustrated the uniform distribution of the irradiance across the sample plane area. It reached the class A of air mass 1.5 for global spectrum (Am1 .5G) (1000 W/m2) covering the 400 nm to 1100 nm wavelength range. The proposed system offered a spectral match of 100%, the temporal instability equivalent to 0.611%, and a non-uniformity of irradiance less than 2%. When the proposed solar simulator was tested in solar cell characteristics under standard test conditions, it was found that the short circuit current error between the sample solar cell under our solar simulator and the standard solar simulator was less than 0.538%. This proposed design is, therefore, an interesting design that can be applied easily and economically further for large scale solar simulators with its modular system.

The degradation of paracetamol (PCT) in an aqueous medium using the Fenton and photo-Fenton reactions was investigated. The aim of this research was the development of a kinetic model based on a reaction mechanism, which includes two main intermediates of PCT degradation and the local volumetric rate of photon absorption (LVRPA). Ferrioxalate was used as a catalyst and the working pH was adjusted to 5.5 (natural pH). Experimental work was planned through a D-optimal experimental design and performed in a flat plate reactor irradiated by a solar simulator. Hydrogen peroxide (HP) concentration, reaction temperature, and radiation level were the operating parameters. The photo-Fenton reaction allowed to reach a minimum relative PCT concentration of 2.01% compared to 5.04% achieved with Fenton reaction. Moreover, the photo-Fenton system required a 50% shorter reaction time and lower HP concentration than in dark conditions (90 min and 189 mg L -1 vs. 180 min and 334 mg L -1 , respectively). The experimental results were used to estimate the kinetic parameters of the proposed kinetic model employing a nonlinear, multi-parameter regression method. The values obtained from the normalized root-mean-square error (14.52, 1.96, 4.36, 13.16, and 8.72 % for PCT, benzoquinone, hydroquinone, HP, and oxalate, respectively) showed a good agreement between the predicted and experimental data.

Previous researchers have detailed the problems in measuring the thermal resistance value of a whole roof assembly under hot conditions due to the uncertainty of the outdoor environment. Currently, no established method exists to experimentally investigate an entire thermal roof performance under a steady-state condition. This article details the properties of the indoor solar simulator and the research methods undertaken to measure the thermal resistance value of roof assembly. The indoor solar simulator utilizes 40 halogen bulbs to accurately replicate sun radiation. Thermocouples and heat flux sensors are installed at several locations on the roof assembly to quantify the heat transmission occurring through it. The thermal resistance value is determined by adding up the average difference in temperature across the external and internal roof surfaces and dividing the total amount by the total of all averaged heat fluxes. Subsequently, this study investigates the thermal efficiency of residential roof assemblies that comprise various insulation materials frequently employed in Malaysia, including stone wool, mineral glass wool, reflective bubble foil insulation, and radiant barriers. The analysis showed that the roof configurations with bubble foil reflective insulation produce superior thermal resistance values when coupled with enclosed air space or mass insulation, with thermal resistance values ranging between 2.55 m2K/W and 3.22 m2K/W. It can be concluded that roof configurations with bubble foil reflective insulation resulted in high total thermal resistance and passed the minimum thermal resistance value of 2.5 m2K/W under the Malaysian Uniform Building By-Law 38 (A) requirements. Furthermore, the radiant barrier produced a high thermal resistance value of 2.50 m2K/W when installed parallel to a 50 mm enclosed air space, emphasising the crucial function of an enclosed air space next to a reflective foil to resist the incoming heat radiation. The findings from this research can help building professionals determine the optimum insulation for residential building roofs in Malaysia.

Irreversible ion migration from the perovskite layer to the charge transport layer and metal electrodes causes irreversible efficiency loss in perovskite solar cells. Confining the mobile ions within the perovskite layer is a promising strategy to improve the long-term operational stability of solar cells. Here we inhibit the migration of iodide ions out of the perovskite under light illumination by creating a depletion region inside the perovskite layer. Precise control of the doping depth induces an electric field within the perovskite that counteracts ion migration while enhancing carrier separation. Our devices exhibit a certified power conversion efficiency of 24.6% and maintain over 88% of the initial efficiency after 1,920 h of continuous illumination under maximum power point conditions (65 °C in ambient air, following the ISOS-L-2 protocol). The power conversion efficiency returns to more than 94% of its initial value after overnight recovery. When operating under repeated 12 h light on/off cycles for over 10,000 h (solar simulator at 65 °C and ambient air, following the ISOS-LC-2 protocol), the efficiency loss is less than 2%. We expect this method to open up new and effective avenues towards enhancing the long-term stability of high-performance perovskite photovoltaics. Controlling the doping depth in perovskites allows the creation of a depletion region that inhibits the migration of iodide ions under illumination. Solar cells exhibit a power conversion efficiency of 24.6% and maintain 88% of the initial efficiency after 1,900 h of continuous operation.

Measurement the outdoor efficiency of photovoltaic (PV) panels is essential, but it is not likely an exceptional circumstance at any given moment is always repeating itself. A solar simulator was designed and fabricated for the purpose of analyzing the performance of PV panel with and without an air cooling mechanism in indoor test. Twenty units of 500 W halogen lamps with build-in reflector support by the steel structure holder act as a natural sunlight. The uniformity of the solar radiation was measured in the test area. Two units of PV panel with same characteristics were experimental in three sets of uniformity of solar radiation, which are 620, 821 and 1016 W/m². The operating temperature of PV panel with an air cooling mechanism can be decreased 2-3 ˚C compared to PV panel reference. The PV panel with an air cooling mechanism can be increased in 3-7 % of maximum power output based on solar radiation. An overall method and procedure of the measurement by the solar simulator are discussed and proposed.

The output characteristics of any solar modules or solar cells are typically assessed according to the standard requirements known as Standard Test Conditions (STC). To meet the STC requirement before commercializing products, manufacturers must subject every fabricated solar cell or module to various tests. These tests include conducting current-voltage characteristics under specific conditions: a solar irradiance of 1000 W/m², a cell temperature of 25°C, and an air mass (AM) of 1.5. This study investigates this STC requirements for developing an alternative measurement platform for photovoltaic cells, specifically focusing on current-voltage characterization of solar cells. Utilizing calibrated photovoltaic cells, the optimal angles for Air Mass 1.0 and 1.5 was identified to be 48.2° and 41.8° respectively. Main methodology was segregated in three stages: first, correlating solar irradiance and illuminance under different light conditions, both outdoor and indoor; second, designing a system with a cooling device to stabilize cell temperature at 25°C; and third, developing a platform to meet AM 1.0 and 1.5 requirements. Results demonstrated varying irradiance outputs for sunlight, halogen lamps, and LED Grow Lights, with the latter achieving 810.2 W/m² under AM 1.5. The study also established optimal voltage and current settings for temperature stabilization, achieving 25°C in 3 minutes. Although the proposed solar simulator design did not reach the targeted 1000 W/m², it offers a feasible low-cost alternative for small-scale applications. The research underscores the technical viability of developing cost-effective solar simulators that meet STC requirements, despite challenges in achieving high irradiance levels with LEDs.

Recently, due to the superior stability and lower risk of toxicity, the development of Pb-free halide double perovskite materials has revived excellent interest. In this work, Pb-free perovskite solar cells (PSCs) with ITO/ETL/Cs 2 AgBiBr 6 /Cu 2 O/Au multilayer structures with Cs 2 AgBiBr 6 double perovskite as the solar light absorber layer, some electron transport layers (ETLs) and Cu 2 O as a hole transport layer have been introduced. Then, the effects of various thicknesses of the absorber layer and also ETL materials, like ZnO, C 60 , CdS, SnO 2 , phenyl-C 61 -butyric acid methyl ester (PCBM), and TiO 2 , on the device performance (including photoelectronic conversion efficiency (PCE), fill factor (FF%), short circuit current density (Jsc), and open-circuit voltage (V OC )) were examined with the help of a solar cell simulator (SCAPS-1D). It is noteworthy that, in the case of all ETL materials, the optimal thickness of the absorber layer was determined to be 400 nm. Then, the maximum PCE values of 20.08%, 17.63%, 14.07%, 12.11%, 14.94%, and 18.83% were obtained for the solar cells containing ZnO, C 60 , CdS, SnO 2 , PCBM, and TiO 2 as the ETL, respectively. These results show that designing/developing Pb-free halide double perovskite devices having comparable PCEs with the Pb-based PSCs is feasible, provided that proper/compatible materials will be used in the multilayer structure of the next generations of solar cells.