Applied Solar Energy最新文献

Biogas technologies play a main role in renewable energy; however, traditional biogas plants often fail to fully exploit the potential of raw materials, focusing solely on energy production. To enhance the efficiency of such systems, the development of hybrid biogas systems, which combine various technological processes, equipment, and energy sources, appears to be a promising approach. This study presents a review of modern engineering solutions in hybrid biogas systems based on patent analysis. A search and analysis of patent literature was conducted, covering the integration of anaerobic digestion with additional biomass treatment methods, biogas purification techniques, and combinations with other renewable energy sources (solar, wind, hydrogen, etc.). The key findings indicate that hybridization of biogas technologies significantly improves the performance and flexibility of biogas plants. Specifically, two-stage digestion increases biogas yield by 15–30%, CO₂ methanation (power-to-methane) raises CH₄ content up to 98%, and combined purification methods (membrane and adsorption) reduce methane losses to less than 1%. Furthermore, the integration of biogas plants with solar or wind energy systems reduces electricity production costs by 20–40%, while also ensuring more stable and predictable generation. The obtained data confirm that hybrid biogas systems enable the comprehensive utilization of organic waste while simultaneously generating energy and valuable by-products (biofertilizers, CO₂ for industrial needs, etc.). The patent analysis, encompassing developments from various countries, highlights a strong global interest in hybrid biogas technologies. Many of the patents are already transitioning from prototype stages to practical implementation, confirming the high potential of hybrid biogas systems for the future of energy. The identified approaches and solutions can be practically applied to modernize existing biogas facilities and develop new, more efficient bioenergy complexes, paving the way for further industry advancement and the realization of clean energy through rational waste management.

This study proposes a method for studying heat flows inside building envelopes based on the theory of nonstationary heat conduction with periodic fluctuations in air temperature. The process of energy accumulation, heat input (heat inflow), and heat loss (heat outflow) through building envelopes is studied as a periodic process. The results of calculating the daily dynamics of heat flows through flat walls are given. The time dependence of integral temperature ({{T}_{{{text{int}}}}}) of flat wall averaged over volume, which determines accumulated heat ({{W}_{{{text{accum}}}}}) in the wall material at any given time of day or for a given time interval, is obtained. It is shown that the change in the ({{T}_{{{text{int}}}}}) value for stationary conditions is 0.5°C when the outside air temperature changes by 1°C. For a periodic heat transfer process, the change in amplitude A_int of fluctuations of the average integral wall temperature is 0.2°C when amplitude A_outs of fluctuations in the outside air temperature changes by 1°C. The daily and seasonal dynamics of ({{T}_{{{text{int}}}}}) and ({{W}_{{{text{accum}}}}}) are determined for the climatic conditions of Central Asia.

The paper presents the results of calculations of technical and economic indicators of energy complexes based on renewable energy sources for heat and power supply of greenhouses. Costs and expenditures of heat energy resources of traditionally used types and on the basis of non-traditional, renewable energy sources for heating of greenhouses located on the ground surface and in the ground at the depth of 0.6 m are determined by calculation. Based on the calculations of technical and economic indicators and climatic conditions, as well as the accumulated experience in the use of resources based on renewable energy sources in the Republic of Uzbekistan prepared the following recommendations: the cost of 1 m³ of gas obtained from a biogas plant is quite acceptable for heating greenhouses, the payback period of biogas plants is 6.6 years of use, taking into account the winter season; when using photovoltaic plants for power supply of greenhouses in comparison with the traditional distribution network, the payback period depending on the type of grown products is from 4 to 6 years; energy resources obtained from renewable energy sources are quite suitable for heating and power supply of greenhouses on the territory of Uzbekistan. The results of calculations show that in greenhouses located on the surface and in the ground, due to the difference in the coefficient of heat of combustion, the consumption of biogas is on average 1.4 times higher. At the same time, the cost of produced energy is much higher than traditional sources when switching to alternative energy sources. The combined use of various energy saving methods allows for a significant reduction in energy production costs from 20 to 40%, depending on the region in Uzbekistan. Thus, energy resources obtained from renewable energy sources are quite suitable for heating and power supply of greenhouses.

This brief correspondence addresses the issue of measurement accuracy in the efficiency of solar cells when using artificial light sources in laboratory conditions. Main attention is paid to the spectral correction of artificial light sources when simulating solar radiation, which is critically important for improving the accuracy of photovoltaic device testing results. The proposed method is based on equating not only the total number of electrons generated by artificial light sources and the solar spectrum, but also on their equalization for each wavelength. This approach helps minimize errors caused by spectral mismatch of different solar cell technologies. The proposed criteria and correction method are based on measurements of the external quantum efficiency (EQE) of elements and do not require the use of a special reference element, as well as allowing the determination of optimal combinations of light sources for each type of photovoltaic technology. The results of the study can serve as a basis for standardizing test procedures and a guide for further research on the improvement and certification of solar technologies.

In this paper, a deep learning Long Short Term Memory (LSTM) controller is designed using multiple optimal PI controllers tuned in different operating regions. It has been previously shown in the literature the impact of climatic conditions and abnormal operating conditions on the power conversion efficiency of photovoltaic (PV) systems. The nonlinear characteristic curve of PV arrays exhibits an additional transient effect that influences the tracking of the Maximum Power Point MPP. The PV power conversion system is characterized by a variable open-loop transient response in the constant current, voltage and power regions, which are subdivisions of the PV array characteristic curve. For the optimal tracking of the reference generated from the MPPT algorithm in these operating regions, an input/output data collection is carried out from the closed-loop system responses using multiple PI controllers tuned in different operating regions. Then, the LSTM controller is tuned using the collected training data constructed from the concatenation of input/output data issued from all operating regions. The dynamic performance evaluation of the deep learning-based LSTM controller for different simulation scenarios, including reference step changes, stair-shaped reference changes and partial shading tracking, shows the high precision and reduced oscillations of the responses issued after using the proposed controller.

To study the influence of optical constants of the polluting film on the efficiency of the photovoltaic module, a fractal model, and a complex medium model are proposed. The fractal dimension of the dust film is determined using images of the surface of the photovoltaic module and solar collector. It is shown that up to the percolation threshold, the calculations of optical constants according to the fractal model and the complex medium model differ by less than 1%. In the process of sedimentation of non-absorbing dust particles on the surface of the photovoltaic module, a clearing effect is possible: an increase in the transmittance of the glass.

The article presents the results of a study on the optimal design of a trench greenhouse with constraints on specific annual thermal load and initial investment. In the first part of the research, an optimal trench greenhouse project was obtained with a constraint on the specific annual thermal load of 50 kWh/(m² year) and an initial investment of $2000. For designing trench greenhouses with limited investment budgets, it is recommended to use double-layer polycarbonate sheets with a thickness of 10 mm, a heat transfer coefficient of 2.75 W/(m² K), and a trench depth of 6.32 cm. If it is necessary to reduce the specific annual thermal load to a level below 33.52 kWh/(m² year), it is recommended to use triple-layer polycarbonate sheets with a thickness of 16 mm, a heat transfer coefficient of 0.62 W/(m² K), and a trench depth of 6.32 cm. An analysis of the second variant of the trench greenhouse project based on the use of aerated concrete blocks and cellular polycarbonate was conducted. The optimized project reduced the specific heating thermal load by 50% compared to the original design and decreased CO₂ emissions by 75%. The total initial investment amounted to $1653.13, with a discounted payback period of 4.7 months. The research results indicate that trench greenhouses can be effective for cultivating agricultural crops. Optimizing the design and construction of trench greenhouses can significantly reduce energy consumption and greenhouse gas emissions.

Since solar radiation observation stations in China are very few, it is necessary to use models to estimate total solar radiation for a small region because solar engineering is established in a specific location. The study selected Gansu province as a case study, in which 6 models were applied to calculate monthly total solar radiation with existing measured data. Through accuracy verification, the Angstrom–Prescot model is proved to be the suitable model for Gansu province. The annual and monthly average total solar radiation for 80 counties in Gansu during 1980–2020 were obtained. The study found that: (1) overall, the annual average total solar radiation showed a fluctuating and slightly downward trend, with a decline rate of 1.87MJ/(m² year) and values between 5102~5640 MJ/m²; (2) spatially, from west to east, the annual average total solar radiation shows a decreasing trend. The solar radiation in the west of Wuwei is the largest, reaching 6394 MJ/m², which is the “richest area” of solar radiation resources. The radiation in Longnan is the smallest with the value of 4259 MJ/m². The monthly average of the multi-year total solar radiation in 80 counties of Gansu province from 1981 to 2020 calculated by the A–P model provides a valuable data basis for solar energy utilization in Gansu province.

The current numerical analysis presents a novel approach for passive cooling of triple-junction (TJ) solar cells integrated with thermoelectric generator (TEG) by an innovative trimmed fins heat sink. The fins design, length and cutting angle are tailored based on the thermal distribution of the hybrid system. The envisaged configuration enables the extraction of excess heat from the cell and its conversion into secondary power via thermoelectric generator. This enhances the system’s cooling efficiency and power generation while minimizing material usage. Three-dimensional thermo-electric model was developed and simulated at various dimensions and cutting angles of the finned heat sink. Results showed that the new trimmed fins heat sink with a flat base area of 2500 mm² and fins cutting angle of 44° is ideally compatible for operating the HCPV TJ cell at the highest possible performance while avoiding significantly increasing the system’s weight. This design improves the TJ cell performance, allowing for maximum allowable solar concentration of 205 and 157 suns at 1 m/s compared to 43.5 and 33 suns for the uncooled reference cell at ambient temperatures of 25 and 45°C, respectively. Accordingly, the system was enabled to generate a higher power of 7.89 and 6.03 W/cm² (based on cell active area), while the uncooled cell is limited to 1.65 and 1.3 W/cm². The remarkable increase in system efficiency caused by the hybrid cooling system achieved environmental benefits by reducing CO₂ emissions by 189.4-ton Co₂/yr⋅m². Finally, Taguchi analysis revealed that the solar incident irradiance concentration ratio has greatest effect on system performance when compared to the other operational variables.

In this work, influence of electron irradiation on the photovoltaic properties of n-type silicon heterojunction solar cells has been investigated. It has been shown that when irradiated with electrons with a fluence of 5 × 10¹⁴ cm^–2, a significant decrease in the quantum efficiency occurs at wavelengths of more than 600 nm, leading to a decrease in the short-circuit current from 33.1 to 22 mA/cm² and the open-circuit voltage from 0.68 to 0.53 V, and at a fluence of 1 × 10¹⁵ cm^–2 up to 18.25 mA/cm² and 0.51 V, respectively. Also, from the load current-voltage characteristics, the values of the surface recombination velocity are ~16 cm/s before irradiation, ~500 cm/s at 5 × 10¹⁴ cm^–2 and 580 cm/s at 1 × 10¹⁵ cm^–2 have been calculated. Using the admittance spectroscopy, a defect with an activation energy of 0.18 eV and capture cross section of σ_n = 5 × 10^–15 cm² was detected in irradiated structures, which may probably be responsible for this behavior of characteristics, its concentration increases with increasing fluence.