On the design, evaluation and performance of an energy efficient solar house with integrated photovoltaics
- Authors: Ziuku, Sosten
- Date: 2011-06
- Subjects: Solar energy , Solar energy -- Environmental aspects , Photovoltaic power generation
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27473 , vital:67331
- Description: The design, construction and performance monitoring of an energy efficient house with integrated photovoltaics is considered. Unlike conventional housing, the house design combines energy efficiency measures and renewable energy technologies into one building structure. The objective of the study was to investigate the feasibility of using energy efficient solar designs to regulate indoor thermal environment, and determine thecost effectiveness and environmental benefits of such housing designs. The use of ordinary photovoltaic panels as a building element for South Africa’s latitude and meteorological conditions was also investigated. The house model was designed using Autodesk Revit architecture and Ecotect building simulation software. Electrical performance was analyzed using RETScreen and PVDesignPRO software. In addition to passive solar design features and clerestory windows, the design has solar water heaters for hot water supply. The designed energy efficient building integrated photovoltaic (EEBIPV) house was built at the University of Fort Hare. A 3.8 kW BIPV generator was mounted on the north facing roof in such a way that the solar panels replace conventional roofing material. A data acquisition system that monitors thermal and electrical performance was installed. The grid independent house has been occupied since February 2009 and its winter indoor thermal efficiency improved from 70 to more than 78% after ceiling installation. Models for indoor thermal performance and BIPV energy and exergy contributions were developed. The avoided energy consumption from the grid has potential to reduce carbon emissions by 12.41 tons per annum. The total building cost per m2 of floor area compares favourably with the cost of commercial middle-to-upper income domestic housing units without energy efficiency measures and building integrated photovoltaics. The research output provides a good framework for the integration of passive solar designs, natural ventilation and lighting, solar water heaters and building integrated photovoltaics into new and existing housing units. , Thesis (MSci) -- Faculty of Science and Agriculture, 2011
- Full Text:
- Authors: Ziuku, Sosten
- Date: 2011-06
- Subjects: Solar energy , Solar energy -- Environmental aspects , Photovoltaic power generation
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27473 , vital:67331
- Description: The design, construction and performance monitoring of an energy efficient house with integrated photovoltaics is considered. Unlike conventional housing, the house design combines energy efficiency measures and renewable energy technologies into one building structure. The objective of the study was to investigate the feasibility of using energy efficient solar designs to regulate indoor thermal environment, and determine thecost effectiveness and environmental benefits of such housing designs. The use of ordinary photovoltaic panels as a building element for South Africa’s latitude and meteorological conditions was also investigated. The house model was designed using Autodesk Revit architecture and Ecotect building simulation software. Electrical performance was analyzed using RETScreen and PVDesignPRO software. In addition to passive solar design features and clerestory windows, the design has solar water heaters for hot water supply. The designed energy efficient building integrated photovoltaic (EEBIPV) house was built at the University of Fort Hare. A 3.8 kW BIPV generator was mounted on the north facing roof in such a way that the solar panels replace conventional roofing material. A data acquisition system that monitors thermal and electrical performance was installed. The grid independent house has been occupied since February 2009 and its winter indoor thermal efficiency improved from 70 to more than 78% after ceiling installation. Models for indoor thermal performance and BIPV energy and exergy contributions were developed. The avoided energy consumption from the grid has potential to reduce carbon emissions by 12.41 tons per annum. The total building cost per m2 of floor area compares favourably with the cost of commercial middle-to-upper income domestic housing units without energy efficiency measures and building integrated photovoltaics. The research output provides a good framework for the integration of passive solar designs, natural ventilation and lighting, solar water heaters and building integrated photovoltaics into new and existing housing units. , Thesis (MSci) -- Faculty of Science and Agriculture, 2011
- Full Text:
On the evaluation of spectral effects on photovoltaic modules performance parameters and hotspots in solar cells
- Authors: Simon, Michael
- Date: 2009
- Subjects: Photovoltaic cells , Energy dissipation , Electric power production , Photovoltaic power generation , Solar energy , Spectral energy distribution
- Language: English
- Type: Thesis , Doctoral , PhD (Physics)
- Identifier: vital:11593 , http://hdl.handle.net/10353/257 , Photovoltaic cells , Energy dissipation , Electric power production , Photovoltaic power generation , Solar energy , Spectral energy distribution
- Description: The performance of photovoltaic (PV) modules in terms of their ability to convert incident photon to electrical energy (efficiency) depends mostly on the spectral distribution of incident radiation from the sun. The incident spectrum finally perceived by the module depends strongly on the composition of the medium in which it has traveled. The composition of the earth’s atmosphere, which includes, amongst others, water vapour, gases such as carbon dioxide and oxygen, absorbs or scatters some of the sunlight. The incident solar spectrum is also modified by the diffuse aspect of radiation from the sky which strongly depends on aerosol concentration, cloudiness and local reflection of the earth’s surface. Although it is well known that the changes in outdoor spectrum affect device performance, little work has been conducted to support this theory. This is probably due to lack of spectral data or in certain instances where data is available, little knowledge of interpreting that data. The outdoor spectral data that one obtains in the field does not come clearly for just simple interpretation. Different analytical interpretation procedures have been proposed, all trying to explain and quantify the spectral influence on PV devices. In this study an assessment methodology for evaluating the effects of outdoor spectra on device performance parameters during the course of the day, seasons and or cloudy cover has been developed. The methodology consists of developing a device dependant concept, Weighted Useful Fraction (WUF) using the outdoor measured spectral data. For measuring PV module’s performance parameters, a current-voltage (I-V) tester was developed in order to monitor the performance of six different module technologies. The Gaussian distribution was used to interpret the data. For hot-spot analysis, different techniques were used, which include Infrared thermographic technique for identifying the hot-spots in the solar cells, SEM and EDX techniques. The AES technique was also used in order to identify other elements at hot-spots sites that could not be detected by the EDX technique. iii Results obtained indicate that multicrystalline modules performance is affected by the changes in the outdoor spectrum during summer or winter seasons. The modules prefer a spectrum characterized by WUF = 0.809 during summer season. This spectrum corresponds to AM 2.19 which is different from AM 1.5 used for device ratings. In winter, the mc-Si module’s WUF (0.7125) peaks at 13h00 at a value corresponding to AM 1.83. Although these devices have a wider wavelength range, they respond differently in real outdoor environment. Results for mono – Si module showed that the device performs best at WUF = 0.6457 which corresponds to AM 1.83 during summer season, while it operates optimally under a winter spectrum indicated by WUF of 0.5691 (AM2.58). The seasonal changes resulted in the shift in WUF during day time corresponding to the “preferred” spectrum. This shift indicates that these devices should be rated using AM values that correspond to the WUF values under which the device operates optimally. For poly-Si, it was also observed the WUF values are lower than the other two crystalline-Si counterparts. The pc-Si was observed to prefer a lower AM value indicated by WUF = 0.5813 during winter season while for summer it prefers a spectrum characterized by WUF = 0.5541 at AM 3.36. The performance of the single junction a-Si module degraded by 67 percent after an initial outdoor exposure of 16 kWh/m² while the HIT module did not exhibit the initial degradation regardless of their similarities in material composition. It was established that the WUF before degradation peaks at 15h00 at a value of 0.7130 corresponding to AM 4.50 while the WUF after degradation “prefers” the spectrum (WUF = 0.6578) experienced at 15h30 corresponding to AM value of 5.57. Comparing the before and after degradation scenarios of a-Si:H, it was observed that the device spends less time under the red spectrum which implies that the device “prefers” a full spectrum to operate optimally. The degradation of a-Si:H device revealed that the device spectral response was also shifted by a 7.7 percent after degradation. A higher percentage difference (61.8 percent) for spectral range for the HIT module is observed, but with no effects on device parameters. Seasonal changes (summer/winter) resulted in the outdoor spectrum of CuInSe2 to vary by WUF = 1.5 percent, which resulted in the decrease in Isc. This was ascertained by iv analyzing the percentage change in WUF and evaluating the corresponding change in Isc. The analysis showed that there was a large percentage difference of the module’s Isc as the outdoor spectrum changed during the course of the day. This confirmed that the 17 percent decrease in Isc was due to a WUF of 1.5 percent. In mc-Si solar cells used in this study, it was found that elemental composition across the entire solar cell was not homogenously distributed resulting in high concentration of transition metals which were detected at hot spot areas. The presence of transition metals causes hot-spot formation in crystalline solar cells. Although several transition elements exist at hot-spot regions, the presence of oxygen, carbon, iron and platinum was detected in high concentrations. From this study, it is highly recommended that transition elements and oxygen must be minimized so as to increase the life expectancy of these devices and improve overall systems reliability
- Full Text:
- Authors: Simon, Michael
- Date: 2009
- Subjects: Photovoltaic cells , Energy dissipation , Electric power production , Photovoltaic power generation , Solar energy , Spectral energy distribution
- Language: English
- Type: Thesis , Doctoral , PhD (Physics)
- Identifier: vital:11593 , http://hdl.handle.net/10353/257 , Photovoltaic cells , Energy dissipation , Electric power production , Photovoltaic power generation , Solar energy , Spectral energy distribution
- Description: The performance of photovoltaic (PV) modules in terms of their ability to convert incident photon to electrical energy (efficiency) depends mostly on the spectral distribution of incident radiation from the sun. The incident spectrum finally perceived by the module depends strongly on the composition of the medium in which it has traveled. The composition of the earth’s atmosphere, which includes, amongst others, water vapour, gases such as carbon dioxide and oxygen, absorbs or scatters some of the sunlight. The incident solar spectrum is also modified by the diffuse aspect of radiation from the sky which strongly depends on aerosol concentration, cloudiness and local reflection of the earth’s surface. Although it is well known that the changes in outdoor spectrum affect device performance, little work has been conducted to support this theory. This is probably due to lack of spectral data or in certain instances where data is available, little knowledge of interpreting that data. The outdoor spectral data that one obtains in the field does not come clearly for just simple interpretation. Different analytical interpretation procedures have been proposed, all trying to explain and quantify the spectral influence on PV devices. In this study an assessment methodology for evaluating the effects of outdoor spectra on device performance parameters during the course of the day, seasons and or cloudy cover has been developed. The methodology consists of developing a device dependant concept, Weighted Useful Fraction (WUF) using the outdoor measured spectral data. For measuring PV module’s performance parameters, a current-voltage (I-V) tester was developed in order to monitor the performance of six different module technologies. The Gaussian distribution was used to interpret the data. For hot-spot analysis, different techniques were used, which include Infrared thermographic technique for identifying the hot-spots in the solar cells, SEM and EDX techniques. The AES technique was also used in order to identify other elements at hot-spots sites that could not be detected by the EDX technique. iii Results obtained indicate that multicrystalline modules performance is affected by the changes in the outdoor spectrum during summer or winter seasons. The modules prefer a spectrum characterized by WUF = 0.809 during summer season. This spectrum corresponds to AM 2.19 which is different from AM 1.5 used for device ratings. In winter, the mc-Si module’s WUF (0.7125) peaks at 13h00 at a value corresponding to AM 1.83. Although these devices have a wider wavelength range, they respond differently in real outdoor environment. Results for mono – Si module showed that the device performs best at WUF = 0.6457 which corresponds to AM 1.83 during summer season, while it operates optimally under a winter spectrum indicated by WUF of 0.5691 (AM2.58). The seasonal changes resulted in the shift in WUF during day time corresponding to the “preferred” spectrum. This shift indicates that these devices should be rated using AM values that correspond to the WUF values under which the device operates optimally. For poly-Si, it was also observed the WUF values are lower than the other two crystalline-Si counterparts. The pc-Si was observed to prefer a lower AM value indicated by WUF = 0.5813 during winter season while for summer it prefers a spectrum characterized by WUF = 0.5541 at AM 3.36. The performance of the single junction a-Si module degraded by 67 percent after an initial outdoor exposure of 16 kWh/m² while the HIT module did not exhibit the initial degradation regardless of their similarities in material composition. It was established that the WUF before degradation peaks at 15h00 at a value of 0.7130 corresponding to AM 4.50 while the WUF after degradation “prefers” the spectrum (WUF = 0.6578) experienced at 15h30 corresponding to AM value of 5.57. Comparing the before and after degradation scenarios of a-Si:H, it was observed that the device spends less time under the red spectrum which implies that the device “prefers” a full spectrum to operate optimally. The degradation of a-Si:H device revealed that the device spectral response was also shifted by a 7.7 percent after degradation. A higher percentage difference (61.8 percent) for spectral range for the HIT module is observed, but with no effects on device parameters. Seasonal changes (summer/winter) resulted in the outdoor spectrum of CuInSe2 to vary by WUF = 1.5 percent, which resulted in the decrease in Isc. This was ascertained by iv analyzing the percentage change in WUF and evaluating the corresponding change in Isc. The analysis showed that there was a large percentage difference of the module’s Isc as the outdoor spectrum changed during the course of the day. This confirmed that the 17 percent decrease in Isc was due to a WUF of 1.5 percent. In mc-Si solar cells used in this study, it was found that elemental composition across the entire solar cell was not homogenously distributed resulting in high concentration of transition metals which were detected at hot spot areas. The presence of transition metals causes hot-spot formation in crystalline solar cells. Although several transition elements exist at hot-spot regions, the presence of oxygen, carbon, iron and platinum was detected in high concentrations. From this study, it is highly recommended that transition elements and oxygen must be minimized so as to increase the life expectancy of these devices and improve overall systems reliability
- Full Text:
Photovoltaic-powered wireless communication system for rural schools outside national utility grid
- Kaseke, Richmore https://orcid.org/0000-0002-8295-5016
- Authors: Kaseke, Richmore https://orcid.org/0000-0002-8295-5016
- Date: 2007-02
- Subjects: Photovoltaic power systems , Photovoltaic power generation
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/29032 , vital:76492
- Description: Access to global information is inarguably one of the key ways of bringing development to any community. In developing worlds, many rural schools lie outside both the Internet Service Provider’s (ISP) cable network and the national utility grid. Rapid developments in information and communication technology (ICT) continue to widen the digital divide between urban and rural schools. In South Africa, although these rural areas are outside the ISP’s cable network, they enjoy excellent mobile (cellular) communications network coverage. Fortunately, leading mobile operators in the country (MTN and Vodacom) have incorporated mobile data packet services into their cellular communication networks since 2002. A stand-alone photovoltaic (PV) system for powering ICT equipment in off grid rural schools was designed and installed; and its performance monitored. Performance of the system was considered in two categories, which are; cost and service performance. In cost performance, return on investment (ROI) and payback period (PB) are the two critical considerations. The PV system designed in this study gave an impressive ROI and PB of 286percent and 5 years, respectively. In order to monitor and evaluate the service performance a data acquisition system (DAS) was designed and installed. Besides proving the potential of PV in powering ICT equipment, results from the DAS also suggested a more efficient way of employing PV as a power source for powering equipment that is based on Switched-Mode Power Supply Units. Concurrent and continuous change in irradiance and temperature result in a four-segment pattern of rising and falling module efficiency throughout the day. Generally, modules produce more energy on cooler sunny days than hotter sunny days. Infrared (IR) Thermography was also used as part of both indoor and outdoor module tests. During indoor tests at pre-deployment stage, IR Thermography showed development of hot spots in mismatched cells of reverse-biased modules. On the outdoors, IR Thermography reiterated the effect of bird droppings on module surfaces byshowing hot spots forming on areas covered by the droppings. For internet connectivity, a customized Mobile Internet Device (MIDevice) was designed, built and tested. The device allows remote computer systems to be connected to the Internet via the already existing mobile communication network using General Packet Radio Services (GPRS). An entire rural school local area network (LAN) can be connected to the Internet via a single MIDevice. An experimental setup was designed in order to monitor and evaluate performance of GPRS in specific and mobile Internet solutions in general. Results obtained proved that GPRS can indeed be a solution for remote Internet connectivity in rural schools. In order to improve performance of GPRS or mobile Internet connections, caching, pop-up blocking and proxy filtering are necessary. , Thesis (MSc) -- Faculty of Science and Agriculture, 2007
- Full Text:
- Authors: Kaseke, Richmore https://orcid.org/0000-0002-8295-5016
- Date: 2007-02
- Subjects: Photovoltaic power systems , Photovoltaic power generation
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/29032 , vital:76492
- Description: Access to global information is inarguably one of the key ways of bringing development to any community. In developing worlds, many rural schools lie outside both the Internet Service Provider’s (ISP) cable network and the national utility grid. Rapid developments in information and communication technology (ICT) continue to widen the digital divide between urban and rural schools. In South Africa, although these rural areas are outside the ISP’s cable network, they enjoy excellent mobile (cellular) communications network coverage. Fortunately, leading mobile operators in the country (MTN and Vodacom) have incorporated mobile data packet services into their cellular communication networks since 2002. A stand-alone photovoltaic (PV) system for powering ICT equipment in off grid rural schools was designed and installed; and its performance monitored. Performance of the system was considered in two categories, which are; cost and service performance. In cost performance, return on investment (ROI) and payback period (PB) are the two critical considerations. The PV system designed in this study gave an impressive ROI and PB of 286percent and 5 years, respectively. In order to monitor and evaluate the service performance a data acquisition system (DAS) was designed and installed. Besides proving the potential of PV in powering ICT equipment, results from the DAS also suggested a more efficient way of employing PV as a power source for powering equipment that is based on Switched-Mode Power Supply Units. Concurrent and continuous change in irradiance and temperature result in a four-segment pattern of rising and falling module efficiency throughout the day. Generally, modules produce more energy on cooler sunny days than hotter sunny days. Infrared (IR) Thermography was also used as part of both indoor and outdoor module tests. During indoor tests at pre-deployment stage, IR Thermography showed development of hot spots in mismatched cells of reverse-biased modules. On the outdoors, IR Thermography reiterated the effect of bird droppings on module surfaces byshowing hot spots forming on areas covered by the droppings. For internet connectivity, a customized Mobile Internet Device (MIDevice) was designed, built and tested. The device allows remote computer systems to be connected to the Internet via the already existing mobile communication network using General Packet Radio Services (GPRS). An entire rural school local area network (LAN) can be connected to the Internet via a single MIDevice. An experimental setup was designed in order to monitor and evaluate performance of GPRS in specific and mobile Internet solutions in general. Results obtained proved that GPRS can indeed be a solution for remote Internet connectivity in rural schools. In order to improve performance of GPRS or mobile Internet connections, caching, pop-up blocking and proxy filtering are necessary. , Thesis (MSc) -- Faculty of Science and Agriculture, 2007
- Full Text:
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