| 1. |
- Aichmayer, Lukas, et al.
(författare)
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Preliminary design and analysis of a novel solar receiver for a micro gas-turbine based solar dish system
- 2015
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Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X .- 1471-1257. ; 114:4, s. 378-396
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Tidskriftsartikel (refereegranskat)abstract
- The solar receiver is one of the key components of hybrid solar micro gas-turbine systems, which would seem to present a number of advantages when compared with Stirling engine based systems and photovoltaic panels. In this study a solar receiver meeting the specific requirements for integration into a small-scale (10 kWel) dish-mounted hybrid solar micro gas-turbine system has been designed with a special focus on the trade-offs between efficiency, pressure drop, material utilization and economic design. A situation analysis, performed using a multi-objective optimizer, has shown that a pressurized configuration, where the solar receiver is placed before the turbine, is superior to an atmospheric configuration with the solar receiver placed after the turbine. Based on these initial design results, coupled CFD/FEM simulations have been performed, allowing detailed analysis of the designs under the expected operating conditions. The results show that the use of volumetric solar receivers to provide heat input to micro gas-turbine based solar dish systems appears to be a promising solution; with material temperatures and material stresses well below permissible limits.
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| 2. |
- An, J., et al.
(författare)
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Stable and efficient PbS colloidal quantum dot solar cells incorporating low-temperature processed carbon paste counter electrodes
- 2017
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Ingår i: Solar Energy. - : Elsevier. - 0038-092X .- 1471-1257. ; 158, s. 28-33
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Tidskriftsartikel (refereegranskat)abstract
- Colloidal quantum dot (CQD) solar cells with a ZnO/PbS-TBAI/PbS-EDT/carbon structure were prepared using a solution processing technique. A commercially available carbon paste that was processed at low-temperatures was used as a counter electrode in place of expensive noble metals, such as Au or Ag, which are used in traditional PbS CQD solar cells. These CQD solar cells exhibited remarkable photovoltaic performance with a short circuit density (Jsc) of 25.6 mA/cm2, an open circuit voltage (Voc) of 0.45 V, a fill factor (FF) of 51.8% and a power conversion efficiency (PCE) as high as 5.9%. A reference device with an Au counter electrode had a PCE of 6.0%. The PCE of the carbon-containing CQD solar cell remained stable for 180 days when tested in ambient atmosphere, while the PCE of the Au-containing CQD solar cell lost 48.3% of its original value. Electrochemical impedance spectroscopy (EIS) demonstrated that holes within the PbS CQD were effectively transported to the carbon counter electrode.
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| 3. |
- Bader, Sebastian, 1984-, et al.
(författare)
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One-diode photovoltaic model parameters at indoor illumination levels – A comparison
- 2019
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Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X .- 1471-1257. ; 180, s. 707-716
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Tidskriftsartikel (refereegranskat)abstract
- Models of photovoltaic devices are used to compare the properties of photovoltaic cells and panels, and to predict their I-V characteristics. To a large extent, modeling methods are based on the one-diode equivalent circuit. Although much research exists on the implementation and evaluation of these methods for typical outdoor conditions, their performance at indoor illumination levels is largely unknown. Consequently, this work performs a systematic study of methods for the parameter extraction of one-diode models under indoor conditions. We selected, reviewed and implemented commonly used methods, and compared their performance at different illumination levels. We have shown that most methods can achieve good accuracies with extracted parameters regardless of the illumination condition, but their accuracies vary significantly when the parameters are scaled to other conditions. We conclude that the physical interpretation of extracted parameters at low illumination is to a large extent questionable, which explains errors based on standard scaling approaches.
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| 4. |
- Bashir, Amna, et al.
(författare)
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Cu-doped nickel oxide interface layer with nanoscale thickness for efficient and highly stable printable carbon-based perovskite solar cell
- 2019
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Ingår i: Solar Energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0038-092X .- 1471-1257. ; 182, s. 225-236
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Tidskriftsartikel (refereegranskat)abstract
- The power conversion efficiency (PCE) of hole conductor free carbon-based perovskite solar cells (PSCs) is restricted by the poor charge extraction and recombination losses at the carbon-perovskite interface. For the first time we successfully demonstrated incorporation of thin layer of copper doped nickel oxide (Cu:NiOx) nanoparticles in carbon-based PSCs, which helps in improving the performance of these solar devices. Cu:NiOx nanoparticles have been synthesized by a facile chemical method, and processed into a paste for screen printing. Extensive X-ray Absorption Spectroscopy (XAS) analysis elucidates the co-ordination of Cu in a NiOx matrix and indicates the presence of around 5.4% Cu in the sample. We fabricated a monolithic perovskite module on a 100 cm(2) glass substrate (active area of 70 cm(2)) with a thin Cu:NiOx layer (80 nm), where the champion device shows an appreciated power conversion efficiency of 12.1% under an AM 1.5G illumination. To the best of our knowledge, this is the highest reported efficiency for such a large area perovskite solar device. I-V scans show that the introduction of Cu:NiOx mesoporous scaffold increases the photocurrent, and yields fill factor (FF) values exceeding 57% due to the better interface and increased hole extraction efficiency. Electrochemical Impedance Spectroscopy (EIS) results reinforce the above results by showing the reduction in recombination resistance (R-rec) of the PSCs that incorporates Cu:NiOx interlayer. The perovskite solar modules with a Cu:NiOx layer are stable for more than 4500 h in an ambient environment (25 degrees C and 65% RH), with PCE degradation of less than 5% of the initial value.
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| 5. |
- Bright, Jamie M., et al.
(författare)
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Improved satellite-derived PV power nowcasting using real-time power data from reference PV systems
- 2018
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Ingår i: Solar Energy. - : Elsevier. - 0038-092X .- 1471-1257. ; 168, s. 118-139
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Tidskriftsartikel (refereegranskat)abstract
- Rapid growth in the global penetration of solar photovoltaic (PV) systems means electricity network operators and electricity generators alike are increasingly concerned with the short-term solar forecasting (nowcasting) of solar irradiance. This paper proposes a methodology that considers a varying number of available reference PV systems for supporting satellite-derived PV power real-time nowcasting. We evaluate conventional satellite-only and upscaling-only PV fleet estimate methodologies and compare them to two newly developed correction and hybrid cases. When using only a single reference PV system to estimate the aggregated power of 48 independent target PV systems for the location of Canberra, Australia; we show that the newly proposed correction or hybrid cases improve the performance of the satellite-derived PV power estimate medians in terms of MBE, rMBE, RMSE and rRMSE from 0.031 W/W-p, 7.46%, 0.079 W/W-p and 23.4%, down to 0.006 W/W-p,-0.711%, 0.068 W/W-p and 20.0%, representing relative improvements of 80.6%, 90.5%, 13.9% and 14.5%, respectively. Similarly, when using 30 reference PV systems, we report median improvements from 0.036 W/W-p, 8.25%, 0.083 W/W-p and 24.8%, down to 0.01 W/W-p, 1.41%, 0.049 W/W-p and 11.4%, representing relative improvements of 72.2%, 82.9%, 41.0% and 54.0%, respectively. We discuss the fundamental challenges facing the use of reference PV systems, satellite-derived power estimates, combining the two data sources, and the knowledge required to address these issues. We ultimately conclude that combining satellite-based PV power estimates with data from reference PV systems is always more beneficial than either on their own.
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| 6. |
- Cabral, Diogo, et al.
(författare)
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Electrical and thermal performance evaluation of symmetric truncated C-PVT trough solar collectors with vertical bifacial receivers
- 2018
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Ingår i: Solar Energy. - : Elsevier Ltd. - 0038-092X .- 1471-1257. ; 174, s. 683-690
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Tidskriftsartikel (refereegranskat)abstract
- One way to reduce solar collectors’ production costs is to use concentrators that increase the output per photovoltaic cell. Concentrating collectors re-direct solar radiation that passes through an aperture into an absorber/receiver. Symmetrical truncated non-tracking C-PVT trough collectors based on a parabola and compound parabolic concentrator (CPC) geometries have been developed. The collector type has a central vertical bifacial (fin) receiver and it was optimized for lower latitudes. In this paper, the electrical and thermal performance of symmetric truncated non-tracking low concentrator PVT solar collectors with vertical bifacial receivers is analysed, through a numerical ray-tracing model software and a multi-paradigm numerical computing environment. A thermal (quasi-dynamic testing method for liquid heating collectors described in the international standard for solar thermal collectors ISO 9806:2013) and electrical performance models were implemented to evaluate the design concepts. The evaluation was made for heating Domestic Hot Water for a Single Family House in Fayoum (Egypt), where CPC geometries with a concentration factor of 1.6 achieved 8 to 13%rel higher energy yields (in kWh/m2/year) than the Pure Parabola geometries.
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| 7. |
- Cabral, Diogo, et al.
(författare)
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Performance Evaluation of Non-Uniform Illumination on a Transverse Bifacial PVT Receiver in Combination with a CPC Geometry
- 2019
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Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X .- 1471-1257. ; 194, s. 696-708
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Tidskriftsartikel (refereegranskat)abstract
- PVT collectors co-generate electricity and heat from the same gross area, thus achieving higher combined heat and electric yields. A comprehensive evaluation has been carried out on non-uniform solar irradiation profile distributions on four symmetric low concentration CPC PVT (LCPVT) solar collector design concepts. Additionally, an electrical and thermal performance evaluation of symmetric truncated LCPVT solar collectors based on a CPC reflector geometry with a central transverse bifacial PVT receiver has been carried out, through a numerical ray-tracing model software and a multi-paradigm numerical computing environment software. A simplified thermal (quasi-dynamic testing method for liquid heating collectors described in the international standard for solar thermal collectors ISO 9806:2017) and electrical performance models were employed to evaluate the LCPVT design concepts. The evaluation was carried out for heating Domestic Hot Water (DHW) for a Single Family House (SFH) in Fayoum (Egypt), where energy yields between 351 and 391 kWh/m2/year have been achieved. The non-uniform solar irradiation assessment showed that the PV cells are exposed to high levels of radiation due to the specific reflector geometry. Furthermore, the study showed that the CPC geometries are very sensitive to the shading effect, as partial shadowing is substantial for high incidence angles.
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| 8. |
- Campana, Pietro Elia, et al.
(författare)
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Optimization and assessment of floating and floating-tracking PV systems integrated in on- and off-grid hybrid energy systems
- 2019
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Ingår i: Solar Energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0038-092X .- 1471-1257. ; 177, s. 782-795
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Tidskriftsartikel (refereegranskat)abstract
- Considering the targets of Thailand in terms of renewable energy exploitation and decarbonization of the shrimp farming sector, this work evaluates several scenarios for optimal integration of hybrid renewable energy systems into a representative shrimp farm. In particular, floating and floating-tracking PV systems are considered as alternatives for the exploitation of solar energy to meet the shrimp farm electricity demand. By developing a dynamic techno-economic simulation and optimization model, the following renewable energy systems have been evaluated: PV and wind based hybrid energy systems, off-grid and on-grid PV based hybrid energy systems, ground mounted and floating PV based hybrid energy systems, and floating and floating-tracking PV based hybrid energy systems. From a water-energy nexus viewpoint, floating PV systems have shown significant impacts on the reduction of evaporation losses, even if the energy savings for water pumping are moderate due to the low hydraulic head. Nevertheless, the study on the synergies between water for food and power production has highlighted that the integration of floating PV represents a key solution for reducing the environmental impacts of shrimp farming. For the selected location, the results have shown that PV systems represent the best renewable solution to be integrated into a hybrid energy system due to the abundance of solar energy resources as compared to the moderate wind resources. The integration of PV systems in off-grid configurations allows to reach high renewable reliabilities up to 40% by reducing the levelized cost of electricity. Higher renewable reliabilities can only be achieved by integrating energy storage solutions but leading to higher levelized cost of electricity. Although the floating-tracking PV systems show higher investment costs as compared to the reference floating PV systems, both solutions show similar competiveness for reliabilities up to 45% due to the higher electricity production of the floating-tracking PV systems. The higher electricity production from the floating-tracking PV systems leads to a better competitiveness for reliabilities higher than 90% due to lower capacity requirements for the storage systems.
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| 9. |
- Carlsson, Bo, 1946-, et al.
(författare)
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Replacing traditional materials with polymeric materials in solar thermosiphon systems : Case study on pros and cons based on a total cost accounting approach
- 2016
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Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X .- 1471-1257. ; 125, s. 294-306
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Tidskriftsartikel (refereegranskat)abstract
- The pros and cons of replacing traditional materials with polymeric materials in solar thermosiphon systems were analysed by adopting a total cost accounting approach.In terms of climatic and environmental performance, polymeric materials reveal better key figures than traditional ones like metals. In terms of present value total cost of energy, taking into account functional capability, end user investment cost, O&M cost, reliability and climatic cost, the results suggest that this may also be true when comparing a polymeric based thermosiphon system with a high efficient thermosiphon system of conventional materials for DHW production in the southern Europe regions. When present values for total energy cost are assessed for the total DHW systems including both the solar heating system and the auxiliary electric heating system, the difference in energy cost between the polymeric and the traditional systems is markedly reduced.The main reason for the difference in results can be related to the difference in thermal performance between the two systems. It can be concluded that the choice of auxiliary heating source is of utmost importance for the economical competiveness of systems and that electric heating may not be the best choice.
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| 10. |
- Dabaieh, Marwa, et al.
(författare)
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An urban living lab monitoring and post occupancy evaluation for a Trombe wall proof of concept
- 2019
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Ingår i: Solar Energy. - : International Solar Energy Society. - 0038-092X .- 1471-1257. ; 193, s. 556-567
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Tidskriftsartikel (refereegranskat)abstract
- Due to extreme climate change events, achieving indoor thermal comfort has become a significant challenge in remote desert areas; particularly with the increasing number of energy shortages in these areas. This study uses participatory action research methodology by means of an occupant centred approach for the design and construction of a Trombe wall system, suitable for passive heating and cooling in hot arid climates. The Trombe wall is used as a low-tech retrofitting passive solution to provide deprived communities in off-grid desert areas with a better indoor climate. The paper presents data from one year of monitoring and post occupancy evaluation for the Trombe wall installed as a retrofit in a residential unit in Sinai, Egypt as a proof of concept. Available affordable local materials were of main concern because of the project’s remote location in a mountainous desert area with very limited natural resources. The idea was to involve the local community in the different phases of the project, then train them onsite on how to use the Trombe wall system. Results indicate that the use of the Trombe wall did in fact enhance indoor heating and cooling loads. In addition, the direct involvement of the local inhabitants proved to have a positive impact on the Trombe wall’s performance and efficiency. The discussion elaborates on key lessons learned and challenges faced from the urban living lab experience presented in the study. Lastly, recommendations for further implementation of the passive Trombe wall system are presented.
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