449,092 research outputs found
Harnessing high altitude solar power
Get PDFAs an intermediate solution between Glaser's satellite solar power (SSP) and ground-based photovoltaic (PV) panels, this paper examines the collection of solar energy using a high-altitude aerostatic platform. A procedure to calculate the irradiance in the medium/high troposphere, based on experimental data, is described. The results show that here a PV system could collect about four to six times the energy collected by a typical U.K.-based ground installation, and between one-third and half of the total energy the same system would collect if supported by a geostationary satellite (SSP). The concept of the aerostat for solar power generation is then briefly described together with the equations that link its main engineering parameters/variables. A preliminary sizing of a facility stationed at 6 km altitude and its costing, based on realistic values of the input engineering parameters, is then presented
The effect of colour on the thermal performance of building integrated solar collectors
No full textThe use of solar collectors with coloured absorbers for water heating is an area of particular interest when considering their integration with buildings. By matching the absorber colour with that of the roof or façade of the building, it is possible to achieve an architecturally and visually pleasing result. Despite the potential for the use of coloured absorbers, very little work has been undertaken in the field.
In this study, the thermal performance of a series of coloured (ranging from white to black), building integrated solar collectors for water heating was examined both theoretically and experimentally. Subsequently, the annual solar fraction for typical water heating systems with coloured absorbers was calculated. The results showed that coloured solar collector absorbers can make noticeable contributions to heating loads. Furthermore, although their thermal efficiency is lower than highly developed selective coating absorbers, they offer the advantage of improved aesthetic integration with buildings
Designing photovolaic/thermal solar collectors for building integration
No full textWith concern growing over the environment and resource use, there has been greater emphasis placed on sustainability, particularly in the built environment. One of the key points of sustainable urban environments is the need for an increase in the densification of the population. A by-product of increased densification however, is a reduction in the area per person that can be used for on-site renewable energy generation from the solar resource. Where previously it would have been possible to have a photovoltaic array and solar water heater side-by-side for a free-standing household, this may not be achievable in a high-density living situation.
As a counterpoint to this issue, the design of a novel combined photovoltaic/thermal for building integration (BIPVT) solar collector is analysed and discussed. The panel has a higher efficiency per unit area, than an array of photovoltaic panels in combination with solar thermal panels. In addition, by integrating electricity generation, water heating and facade elements it is possible to reduce the complexity associated with traditional solar installations while also achieving an architecturally sensitive appearance. As such the BIPVT is ideally suited to environments where facade space with suitable solar access is limited, or where large numbers of people share a single building.
In this study, the influence of key design parameters on the performance of a BIPVT collector are presented and discussed. Finally, a transient systems analysis is used to illustrate the performance benefits of BIPVT style collectors over traditional technologies
Gossamer roadmap technology reference study for a solar polar mission
No full textA technology reference study for a solar polar mission is presented. The study uses novel analytical methods to quantify the mission design space including the required sail performance to achieve a given solar polar observation angle within a given timeframe and thus to derive mass allocations for the remaining spacecraft sub-systems, that is excluding the solar sail sub-system. A parametric, bottom-up, system mass budget analysis is then used to establish the required sail technology to deliver a range of science payloads, and to establish where such payloads can be delivered to within a given timeframe. It is found that a solar polar mission requires a solar sail of side-length 100 – 125 m to deliver a ‘sufficient value’ minimum science payload, and that a 2. 5μm sail film substrate is typically required, however the design is much less sensitive to the boom specific mass
Performance of a building integrated photovoltaic/thermal (BIPVT) solar collector
No full textThe idea of combining photovoltaic and solar thermal collectors (PVT collectors) to provide electrical and heat energy is an area that has, until recently, received only limited attention. Although PVTs are not as prevalent as solar thermal systems, the integration of photovoltaic and solar thermal collectors into the walls or roofing structure of a building could provide greater opportunity for the use of renewable solar energy technologies. In this study, the design of a novel building integrated photovoltaic/thermal (BIPVT) solar collector was theoretically analysed through the use of a modified Hottel–Whillier model and was validated with experimental data from testing on a prototype BIPVT collector.
The results showed that key design parameters such as the fin efficiency, the thermal conductivity between the PV cells and their supporting structure, and the lamination method had a significant influence on both the electrical and thermal efficiency of the BIPVT. Furthermore, it was shown that the BIPVT could be made of lower cost materials, such as pre-coated colour steel, without significant decreases in efficiency.
Finally, it was shown that by integrating the BIPVT into the building rather than onto the building could result in a lower cost system. This was illustrated by the finding that insulating the rear of the BIPVT may be unnecessary when it is integrated into a roof above an enclosed air filled attic, as this air space acts as a passive insulating barrier
Selenization kinetics inCu2ZnSn(S,Se)4 solar cells prepared from nanoparticle inks
No full textEarth-abundant Cu2ZnSn(S,Se)4 (CZTSSe) thin film photovoltaic absorber layers are fabricated by annealing Cu2ZnSnS4 (CZTS) nanoparticle thin films in a selenium rich atmosphere. Systematic variation of the selenization time (5, 10, 20 and 40 min) and temperature (450, 500, 550 and 600 °C) provides insight into the kinetics of the selenization process and in particular recrystallization and grain growth. Se–S anion exchange is found to follow Avrami׳s model in which the CZTS selenization is controlled by an irregular one-dimensional process limited by metal cation re-ordering and grain boundary migration. CZTSSe grain growth is observed to follow a normal relation with a grain growth exponent close to the ideal case of equiaxed grains and the grain boundary migration energy is calculated to be 85.38 kJ/mol. These selenization variables have a fundamental influence on the quality of the resulting CZTSSe thin film and consequently the device performance. A peak device solar energy conversion efficiency of 5.4% was obtained for selenization at 500 °C for 20 min. The device efficiency was found to be highly sensitive to these variables and it is critical to obtain an appropriate balance between grain growth and thin film quality
Solar cycle dependence of scaling in solar wind fluctuations
Get PDFIn this review we collate recent results for the statistical scaling properties of fluctuations in the solar wind with a view to synthesizing two descriptions: that of evolving MHD turbulence and that of a scaling signature of coronal origin that passively propagates with the solar wind. The scenario that emerges is that of coexistent signatures which map onto the well known "two component" picture of solar wind magnetic fluctuations. This highlights the need to consider quantities which track Alfvénic fluctuations, and energy and momentum flux densities to obtain a complete description of solar wind fluctuations
Can PV or solar thermal systems be cost effective ways of reducing CO 2 emissions for residential buildings?
No full textThis paper compares two solar systems, an actual building integrated, photovoltaic roof (BIPV) and a notional solar thermal system for a residential block in London, UK. The carbon payback for the solar thermal system is 2 years, the BIPV system has a carbon payback of 6 years. Simple economic payback times for both systems are more than 50 years. Calculations considering the current UK energy price increase (10%/yr), reduce the economic payback time for the PV roof to under 30 years.The costs to reduce overall carbon dioxide emissions using a BIPV roof are £196/tonne CO2, solar thermal individual systems at £65/tonne CO2 and community solar thermal at £38/tonne CO2. The current spot market price for CO2 is £15/tonne CO2 (20). Capital costs for PV systems in particular must be significantly reduced for them to be a cost-effective way to reduce CO2. This paper compares two solar systems, an actual building integrated, photovoltaic roof (BIPV) and a notional solar thermal system for a residential block in London, UK. The carbon payback for the solar thermal system is 2 years, the BIPV system has a carbon payback of 6 years. Simple economic payback times for both systems are more than 50 years. Calculations considering the current UK energy price increase (10%/yr), reduce the economic payback time for the PV roof to under 30 years.The costs to reduce overall carbon dioxide emissions using a BIPV roof are £196/tonne CO2, solar thermal individual systems at £65/tonne CO2 and community solar thermal at £38/tonne CO2. The current spot market price for CO2 is £15/tonne CO2 (20). Capital costs for PV systems in particular must be significantly reduced for them to be a cost-effective way to reduce CO2
Market potential of solar thermal enhanced oil recovery-a techno-economic model for Issaran oil field in Egypt
No full textSolar thermal enhanced oil recovery (S-EOR) is an advanced technique of using concentrated solar power (CSP) technology to generate steam and recover oil from maturing oil reservoirs. The generated steam is injected at high pressure and temperature into the reservoir wells to facilitate oil production. There are three common methods of steam injection in enhanced oil recovery - continuous steam injection, cyclic steam stimulation (CSS) and steam assisted gravity drainage (SAGD). Conventionally, this steam is generated through natural gas (NG) fired boilers with associated greenhouse gas emissions. However, pilot projects in the USA (Coalinga, California) and Oman (Miraah, Amal) demonstrated the use of S-EOR to meet their steam requirements despite the intermittent nature of solar irradiation. Hence, conventional steam based EOR projects under the Sunbelt region can benefit from S-EOR with reduced operational expenditure (OPEX) and increased profitability in the long term, even with the initial investment required for solar equipment. S-EOR can be realized as an opportunity for countries not owning any natural gas resources to make them less energy dependent and less sensible to gas price fluctuations, and for countries owning natural gas resources to reduce their gas consumption and export it for a higher margin. In this study, firstly, the market potential of S-EOR was investigated worldwide by covering some of the major ongoing steam based EOR projects as well as future projects in pipeline. A multi-criteria analysis was performed to compare local conditions and requirements of all the oil fields based on a defined set of parameters. Secondly, a modelling approach for S-EOR was designed to identify cost reduction opportunities and optimum solar integration techniques, and the Issaran oil field in Egypt was selected for a case study to substantiate the approach. This modelling approach can be consulted to develop S-EOR projects for any steam flooding based oil fields. The model was developed for steam flooding requirements in Issaran oil field using DYESOPT, KTH's in-house tool for techno-economic modelling in CSP.</p
ASO-S: Advanced Space-based Solar Observatory
No full textASO-S is a mission proposed for the 25th solar maximum by the Chinese solar community. The scientific objectives are to study the relationships among solar magnetic field, solar flares, and coronal mass ejections (CMEs). ASO-S consists of three payloads: Full-disk Magnetograph (FMG), Lyman-alpha Solar Telescope (LST), and Hard X-ray Imager (HXI), to measure solar magnetic field, to observe CMEs and solar flares, respectively. ASO-S is now under the phase-B studies. This paper makes a brief introduction to the mission. © 2015 SPIE
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