Renewable Energy Resources and Technologies
Gopal Nath Tiwari; Shikha Singh; Yashwant Kumar Singh
Abstract
This paper presents an analytical expression for the temperatures of the plant, room air, and solar cell, as well as the electrical efficiency, for a photo-voltaic thermal (PVT) roof façade of a greenhouse integrated semi-transparent photovoltaic thermal (GiSPVT) system. The expression considers ...
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This paper presents an analytical expression for the temperatures of the plant, room air, and solar cell, as well as the electrical efficiency, for a photo-voltaic thermal (PVT) roof façade of a greenhouse integrated semi-transparent photovoltaic thermal (GiSPVT) system. The expression considers climatic variables such as solar intensity and ambient air temperature, as well as design parameters such as the area of the PV module, electrical efficiency under standard test conditions (STC), temperature coefficient, and various heat transfer coefficients. Using monthly numerical computations for different parameters in Indian climatic conditions, this study evaluates energy matrices such as energy payback time (EPBT), energy production factor (EPF), and life cycle conversion efficiency (LCCE) for various solar cell materials, including single-crystalline (c-Si), multi-crystalline (mc-Si), amorphous (a-Si), copper indium gallium diselenide (CIGS), and cadmium telluride (CdTe), with and without thermal exergy. Considering that the life span of greenhouse materials varies from 5-30 years for low cost, medium, and high-tech greenhouses, different solar cell materials are recommended for different life spans of GiSPVT. Therefore, this study recommends suitable solar cell materials for known greenhousedesigns:(a) The EPBT and (LCCE considering thermal exergy for c-Si/mc-Si range from approximately 3.5 to 4.5 years and 13 to 22%, respectively. Consequently, these values render crystalline silicon solar cells highly fitting for application in high-tech greenhouses with a comparable lifespan.(b) For the CIGS, the EPBT is 1.17 years with an associated LCCE (including thermal exergy) of 16.44%. This establishes CIGS as particularly well-suited for deployment in cost-effective greenhouse environments designs:(a) EPBT and LCCE for c-Si/ mc-Si are about 3.5 to 4.5 years and 13 to 22%, respectively, with respect to thermal exergy. Hence, these two solar cell materials are most suitable for high-tech greenhouses that are similar to crystalline solar cell in terms of life cycle. (b) EPBT and LCCE of CIGS are 1.17 years and 16.44%, respectively, with respect to thermal exergy. Hence, the solar cell material of CIGS is most suitable for low-cost greenhouses.
Renewable Energy Resources and Technologies
Gopal Nath Tiwari; Prashant Bhardwaj; Sujata Nayak
Abstract
This study considers N-photovoltaic thermal-thermo electric cooler (PVT-TEC) air collectors connected in series for thermal and electrical performance. An improved Hottel-Whiller-Bliss (HWB) equation and mass flow rate factor were derived for the nth PVT-TEC air collectors. The derivation is based on ...
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This study considers N-photovoltaic thermal-thermo electric cooler (PVT-TEC) air collectors connected in series for thermal and electrical performance. An improved Hottel-Whiller-Bliss (HWB) equation and mass flow rate factor were derived for the nth PVT-TEC air collectors. The derivation is based on energy balance equation for each component of N-photovoltaic thermal-thermo electric cooler (PVT-TEC) air collectors connected in series. Further, thermal energy and electrical energy from PV module and TEC were analyzed based on a given design and climatic parameters along with the overall exergy of the proposed system on the hourly and daily bases. Numerical computations were conducted using MATLAB under Indian climatic conditions. The proposed thermal model is valid for all climatic and weather conditions. Based on the numerical computations carried out, the following conclusions were made:The electrical power of PV module decreased with increase in the number of the n^th PVT-TEC air collectors as the electrical power of TEC increased.The overall instantaneous exergy efficiency decreased with increase in the number of the n^th PVT-TEC air collectors.Packing factor of TEC was found to be a very sensitive parameter for optimizing the number of PVT-TEC air collectors to ensure maximum overall exergy, and it was found to be β_tec=0.5. for N=7
