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SOLARAWARDS2011 SHOR TLISTED


productive green ventures, utilizing land space that cannot be used for other applications. Specifically SPG Solars installation at a former military base (Depot Park) in Northern California demonstrates an in-depth solution to a global problem that is becoming of increasing concern for people, countries, governments, consumers and industry around the world.


Challenge


SPG Solars deployment of solar energy installations on brownfields addresses these challenges: Developing productive usage of land that cannot be used for other purposes. Air quality Pressure on municipality and government agency budgets Job creation


Problem Solved The Fischer Properties Depot Park Project: Provides a productive use for a hazardous waste site, land that could not be used for other purposes. Will save more than 3,000 tons of greenhouse gas emissions annually. Produces enough power to meet approximately 40% of the annual electricity needs at Depot Park. Created nearly 100 jobs


Noteworthy


The installation is one of the largest ground mounted-tracking solar projects in California and the only one located at a Superfund Site within a redeveloped military facility. SPG Solar developed this solar installation in cooperation with state, city and municipal officials.


Dick Fischer, president of U.S. National Leasing, owner and manager of Depot Park said, “It serves as a shining example of both alternative energy ingenuity and green energy remediation of a previously contaminated brownfield site.


It promotes both the state’s climate change initiatives and the city’s effort to attract green industry businesses to Sacramento.” The project typifies the US Department of Energy’s initiative to turn brownfields into brightfields.


Recognizing the potential impact of solar projects like Fischer Properties Depot Park, the DOE reports that if the 15 million acres of brownfield space in the US alone were converted into brightfields it would provide 3 million megawatts (MWs) of electricity.


Solar Radome


A novel planar antenna by using a panel of photovoltaic cells as a metamaterial FSS radome for dual-band operation is presented. A 10-Watt, 72-cell unmodified commercial photovoltaic panel is applied as a transparent layer in the first operation band and as a semi-transparent layer for Ï/2 Fabry-Pérot cavity in the second operation band to achieve high antenna gain. The proposed prototype achieves remarkable 17.3 dBi and 6.6 dBi antenna gain at 3.5 GHz and 1.23 GHz, respectively by feeding a dual-band dipole. With the aid of PV panel, the antenna can support an upper band at about 3550 MHz to cover the WiMAX 3.5 GHz (3400-3600 MHz) operation band and a lower band at about 1185 MHz to cover the 70 MHz operation bandwidth. The very combination of photovoltaic cell and antenna exhibits high fill factor, high- gain, and simple construction characteristics. This integration of PV panel and antenna is suitable for outdoor wireless communication devices such as IEEE 802.11 a/b or WiMAX (IEEE 802.16e) access points, 3GPP LTE femtocells.


Challenge


The main challenge is to overcome the EM interference when conducting the integration of antenna and PV panels. Since the conductivity of a commercial PV cell is so high to about 100-200 s/m that it is treated as a conductor which will block the EM wave when incidents into the PV panels. To treat the PV panel as an interference load or as a RF antenna ground is currently, the only solution to reach the coexistence of the PV panel and antenna. Therefore, a unique method is proposed to solve the integration of PV panel and antenna EM compatible issue. The goal is to maintain both the PV panel and the antenna area ratio.


Industry Development Award


Problem Solved Inspired by the concept of metamaterialFabry-Pérot resonator, we treat the PV cell as a sub-wavelength periodic structure which having the proper frequency selective characteristic in the desired operation band and construct a novel high gain antenna. A dual-band high-gain antenna is fabricated in a very reasonable, area-saving manner without any major modification of PV cells construction. In other words, the filling factor (or area ratio) of PV cell can be well-maintained in our proposed integration design. That also means it contains the same optical efficiency as the ordinary PV cell. In addition, owing to the PV-cell-FSS arrangement and the proper calculation of Fabry-Pérot resonance condition, its very promising for antenna gain improvement (~10 dB comparing to an ordinary single patch antenna) and industrial manufacturing.


Noteworthy


The Electromagnetic inference must be taken into account while constructing the PV-Antenna integrating structure. In our proposed design, the parameters of PV- Cell area ratio has been improved to 90% and the antenna efficiency to more than 80% in contrast of 20% and 39% from SOLANT project supported by the European Space Agency[1] whose PV cell and antenna are arranged in interlacing mode , 50% and 50% from Institute for Solar Energy Supply Technology (ISET)[2] as an antenna radiator and 90% and 32% of Dublin Institute of Technology [3] as an antenna ground. For more detailed structure, please see our comparison table 1 in the attached PDF file. It should be noted that the PV panels/cells area ratio and antenna efficiency is a trade off in all of the designs in [1-3]. None of them can be treated as well arranged matrix in sub- wavelength periodic structure.


Innovation


Our technology is Electromagnetic Metamaterial. Since the pioneer theoretical work by Veselago in 1968 [4] and later the experimental realization by Smith et al. [5], there has been an exploding research interest in metamaterialsubstances that exhibit simultaneously negative permittivity and permeability. This is mainly due to the fact that this new class of artificial material opens up new opportunities in EM design that were not possible before.


Issue VIII 2011 I www.solar-pv-management.com 37


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