A Technological Objective
To research the possibility to utilize commercial grade glass mirror as a reflective material in solar hot water applications which can operate in various climatic conditions (from -20 deg C to 45 deg. C)? At present, the solar concentrator designs use custom made low iron parabolic glass mirrors. However, this option is expensive and not practical for the average consumer. Furthermore, the maintenance costs of the custom made mirrors is very high, The technological objective is to research possible utilization of commercial grade, low cost, glass mirror sheets as a reflective material in Solar Concentrator application. This research will allow potentially standard glass mirrors to be used in Solar Concentrator designs from 3.6 m to 7.2m.
As result, a single 7.2 m X 7.2m solar concentrator might be able to deliver 46kW ( @ 1000W/m2) of heat and 13.8kW of electricity ( PV Cell 3 junction @ 30% efficiency, Size -0.4m2)
Scientific or Technological Advancement
The research will allow engineers to utilize standard commercial grade glass mirrors in solar hot water systems and improve the understanding of the optics in Solar Energy harvesting process. The researched material will aid engineers and designers to develop a new generation of commercially viable Solar Concentrators. Currently, the existing Solar Concentrators suffers from the following:
Complicated optic design
High cost of production
High maintenance cost
Elaborate dual axis sun tracking system
The research consists of investigating the various parabolic deign structures in conjunction with standard glass mirror sheets to achieve 90% energy harvesting in the focal point. In addition, the research will potentially find a possible solution to overcome the high cost of manufacturing in the current Solar Concentrator designs. This research will help to develop technical knowledge in this new field of Solar Energy and will improve the viability of solar energy. As a result, the SolarBeam Solar Concentrator will become a common site in people’s backyards, which will help the global warming situation and definitely will reduce dependence on fossil fuels. In addition, it will indirectly reduce green house gas emissions. Furthermore, this scientific and technological research will lead to the development of new generation of solar Concentrators to power homes and provide renewable energy to industries and commercial buildings.
The conducted research will provide the following technological advancements:
Cost reduction of sun reflective material
New parabolic optic design concepts
Improved reliability of Solar Concentrator from –20 deg. C to 45 deg C
Scientific or technological uncertainty
The technological uncertainty is the fact that a flat sheet of glass mirror is subjected to physical stress due to the flexing of the glass sheet. The breakage occurs when the tensile stresses exceed the glass edge strength. In addition, the following question needs to be answered: Can various stresses relieve technologies be applied to the glass mirror to reduce the stress in the material under diversified climatic conditions? This challenging question creates scientific and technological uncertainty. Various structural concepts need to be researched before it can be concluded that there is a possibility to utilize commercial grade glass mirror sheets as a reflective material in Solar Concentrators. The glass mirror must be researched under the following conditions:
Physical stress
Thermal stress
Various wind conditions ( 0- 196 km)
Various temperature conditions ( -20 deg. C to 45C deg.)
For example, it was found that the flat sheet glass mirror performed quite well at 20 deg. C one day and the next day, the same glass mirror experienced breakage at 12 deg. C. It was found that the higher incidents of breakage occurred under diversified temperature conditions. Can a new technology release the stress before the fracture destroys the mirror? The appropriate research; testing and evaluation must be studied to analyze the situation. As result, there is great scientific uncertainty regarding the outcome of the research regarding the possibility of using standard commercially available glass mirrors in solar hot water applications. Currently, there is not a single company which commercially manufactures Solar Concentrators made out of flat sheet glass mirrors.
Summary- Flat glass mirror in Solar Concentrator application creates technological uncertainty for the following reasons:
Can various stress relieving design technologies be developed to reduce the stress in the glass under diversified climatic conditions, so it could be applied as a reflective material in Solar Concentrators?
Edward Herniak
CEO/Pesident
SolarTron Energy Systems
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