scholarly journals Comparison of Electrical and Thermal Performances of Glazed and Unglazed PVT Collectors

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Jin-Hee Kim ◽  
Jun-Tae Kim
Keyword(s):  
Thermal Energy ◽  
Energy Performance ◽  
Solar Thermal ◽  
Electrical Performance ◽  
Unit Surface Area ◽  
Electrical Efficiency ◽  
Photovoltaic Modules ◽  
Pv Module ◽  
Solar Thermal Collectors ◽  
Liquid Type

Photovoltaic-thermal (PVT) collectors combine photovoltaic modules and solar thermal collectors, forming a single device that receives solar radiation and produces electricity and heat simultaneously. PVT collectors can produce more energy per unit surface area than side-by-side PV modules and solar thermal collectors. There are two types of liquid-type flat-plate PVT collectors, depending on the existence of glass cover over PV module: glass-covered (glazed) PVT collectors, which produce relatively more thermal energy but have lower electrical yield, and uncovered (unglazed) PVT collectors, which have relatively lower thermal energy with somewhat higher electrical performance. In this paper, the experimental performance of two types of liquid-type PVT collectors, glazed and unglazed, was analyzed. The electrical and thermal performances of the PVT collectors were measured in outdoor conditions, and the results were compared. The results show that the thermal efficiency of the glazed PVT collector is higher than that of the unglazed PVT collector, but the unglazed collector had higher electrical efficiency than the glazed collector. The overall energy performance of the collectors was compared by combining the values of the average thermal and electrical efficiency.

scholarly journals The Experimental Performance of an Unglazed PVT Collector with Two Different Absorber Types

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Jin-Hee Kim ◽  
Jun-Tae Kim
Keyword(s):  
Thermal Energy ◽  
Electrical Performance ◽  
Experimental Performance ◽  
Photovoltaic Modules ◽  
Glass Cover ◽  
Pv Module ◽  
Pv Modules ◽  
Solar Thermal Collectors ◽  
Tube Type ◽  
Liquid Type

Photovoltaic-thermal collectors combine photovoltaic modules and solar thermal collectors, forming a single device that produces electricity and heat simultaneously. There are two types of liquid-type PVT collectors, depending on the existence or absence of a glass cover over the PV module. The glass-covered (glazed) PVT collector produces relatively more thermal energy but has a lower electrical yield, whereas the uncovered (unglazed) PVT collector has a relatively low thermal energy and somewhat higher electrical performance. The thermal and electrical performance of liquid-type PVT collectors is related not only to the collector design, such as whether a glass cover is used, but also to the absorber design, that is, whether the absorber is for the sheet-and-tube type or the fully wetted type. The design of the absorber, as it comes into contact with the PV modules and the liquid tubes, is regarded as important, as it is related to the heat transfer from the PV modules to the liquid in the tubes. In this paper, the experimental performance of two liquid-type PVT collectors, a sheet-and-tube type and a fully wetted type, was analyzed.

scholarly journals A Study of Optimal Specifications for Light Shelves with Photovoltaic Modules to Improve Indoor Comfort and Save Building Energy

2021 ◽  
Vol 18 (5) ◽  
pp. 2574
Author(s):  
Heangwoo Lee ◽  
Xiaolong Zhao ◽  
Janghoo Seo
Keyword(s):  
Energy Savings ◽  
Building Energy ◽  
Energy Performance ◽  
Building Energy Efficiency ◽  
Efficiency Change ◽  
Photovoltaic Modules ◽  
Heating And Cooling ◽  
Pv Module ◽  
Pv Modules ◽  
Indoor Comfort

Recent studies on light shelves found that building energy efficiency could be maximized by applying photovoltaic (PV) modules to light shelf reflectors. Although PV modules generate a substantial amount of heat and change the consumption of indoor heating and cooling energy, performance evaluations carried out thus far have not considered these factors. This study validated the effectiveness of PV module light shelves and determined optimal specifications while considering heating and cooling energy savings. A full-scale testbed was built to evaluate performance according to light shelf variables. The uniformity ratio was found to improve according to the light shelf angle value and decreased as the PV module installation area increased. It was determined that PV modules should be considered in the design of light shelves as their daylighting and concentration efficiency change according to their angles. PV modules installed on light shelves were also found to change the indoor cooling and heating environment; the degree of such change increased as the area of the PV module increased. Lastly, light shelf specifications for reducing building energy, including heating and cooling energy, were not found to apply to PV modules since PV modules on light shelf reflectors increase building energy consumption.

A System Modeling Approach for Active Solar Heating and Cooling System With Phase Change Material (PCM) for Small Buildings

2012 ◽  
Author(s):  
Rajeevan Ratnanandan ◽  
Jorge E. González
Keyword(s):  
Phase Change ◽  
Thermal Energy ◽  
Cooling System ◽  
Hot Water ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Adsorption Chiller ◽  
Heating And Cooling ◽  
Solar Thermal Collectors ◽  
Change Material

The paper presents a study of the performance of an active solar thermal heating and cooling system for small buildings. The work is motivated by the need for finding sustainable alternatives for building applications that are climate adaptable. The energy demand for heating and cooling needs in residential and light commercial buildings in mid-latitudes represent more than 50% of the energy consumed annually by these buildings. Solar thermal energy represents an untapped opportunity to address this challenge with sustainable solutions. Direct heating could be a source for space heating and hot water, and for heat operated cooling systems to provide space cooling. However, a key limitation in mainstreaming solar thermal for heating and cooling has been the size of thermal storage to implement related technologies. We address this issue by coupling a Phase Change Material (PCM) with an adsorption chiller and a radiant flooring system for year round solar thermal energy utilization in Northern climates. The adsorption chiller allows for chill water production driven by low temperature solar thermal energy for summer cooling, and low temperature radiant heating provides for space heating in winter conditions, while hot water demand is supplied year round. These active systems are operated by high performance solar thermal collectors. The PCM has been selected to match temperatures requirements of the adsorption chiller, and the tank was designed to provide three levels of temperatures for all applications; cooling, heating, and hot water. The material selection is paraffin sandwiched with a graphite matrix to increase the conductivity. The specific objective of the preset work is to provide a system optimization of this active system. The system is represented by a series of mathematical models for each component; PCM tank with heat exchangers, the adsorption machine, the radiant floor, and the solar thermal collectors (Evacuated tubular collectors). The PCM modeling allows for sensible heating, phase change process, and superheating. Parametric simulations are conducted for a defined small building in different locations in US with the objective of defining design parameters for; optimal solar collector array, sizing of the PCM tank, and performance of the adsorption machine and radiant heating system. The monthly and annual solar fractions of the system are also reported.

Trends and Opportunities in Direct-Absorption Solar Thermal Collectors

2013 ◽  
Vol 5 (2) ◽  
Author(s):  
Patrick Phelan ◽  
Todd Otanicar ◽  
Robert Taylor ◽  
Himanshu Tyagi
Keyword(s):  
Energy Conversion ◽  
Thermal Energy ◽  
Solar Thermal ◽  
Working Fluid ◽  
Direct Absorption ◽  
Solar Thermal Energy ◽  
Thermal Energy Conversion ◽  
Recent Developments ◽  
Solar Thermal Collectors ◽  
Photocatalytic Reactions

Efficient conversion of sunlight into useful heat or work is of increasing global interest. Solar-to-thermal energy conversion, as opposed to solar-to-electricity, is enabled by solar thermal collectors that convert sunlight into heat at some useful temperature. We review here recent developments in solar thermal energy conversion. Our emphasis is on “direct-absorption” solar thermal collectors, in which incident sunlight is absorbed directly by a working fluid. This contrasts with conventional solar thermal collectors where the sunlight strikes and is absorbed by a solid receiver, which then transfers heat to the working fluid. Both liquid-based and gas-based direct-absorption collectors are described, although liquid-based systems are emphasized. We propose that if “direct-absorption” technologies could be developed further, it would open up a number of emerging opportunities, including applications exploiting thermochemical and photocatalytic reactions and direct absorption of a binary fluid for absorption refrigeration.

scholarly journals Experimental Study on the Performance of a Phase Change Slurry-Based Heat Pipe Solar Photovoltaic/Thermal Cogeneration System

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Hongbing Chen ◽  
Yutong Gong ◽  
Ping Wei ◽  
Pingjun Nie ◽  
Yaxuan Xiong ◽  
...  
Keyword(s):  
Phase Change ◽  
Heat Pipe ◽  
Thermal Energy ◽  
Unit Area ◽  
Energy Performance ◽  
Hot Water ◽  
Electrical Performance ◽  
Working Fluid ◽  
Solar Pv ◽  
T System

By employing phase change slurry (PCS) as working fluid for the heat pipe solar PV/T system, the study is designed to investigate the electrical and thermal energy performance of the system. Meanwhile, through examining the performance difference between water-based and PCS-based heat pipe solar PV/T systems, 30% alkyl hydrocarbon PCS is proved to be a suitable working fluid for optimized energy performance based on the combined consideration of the thermophysical and rheological properties. Both static and dynamic stability tests show that 30% alkyl hydrocarbon PCS has a good stability for low-temperature thermal energy storage. A testing rig is constructed consisting of two identical heat pipe solar PV/T cogeneration systems A and B, in which water and 30% alkyl hydrocarbon PCS are, respectively, employed as working fluids; the energy performance of those two PV/T systems are investigated and compared with each other under the same testing condition. The results indicate that the application of PCS to the heat pipe PV/T system leads to a significant improvement in thermal performance and a modest growth in electrical performance. The daily heat gains and overall average efficiency of system B are 4.2 MJ/m2 (per unit area of PV/T panel) and 59.3%, respectively, 27.3% and 9.3% higher than those of system A. Per unit area of the heat pipe PV/T panel could produce 55.2 L domestic hot water of about 45°C on a sunny day.

scholarly journals Soiling of Photovoltaic Modules: Comparing between Two Distinct Locations within the Framework of Developing the Photovoltaic Soiling Index (PVSI)

2019 ◽  
Vol 11 (17) ◽  
pp. 4697 ◽  
Author(s):  
Thamer Alquthami ◽  
Karim Menoufi
Keyword(s):  
Simple Procedure ◽  
Outdoor Environment ◽  
Electrical Performance ◽  
Dust Density ◽  
Photovoltaic Modules ◽  
Future Performance ◽  
Pv Module ◽  
Pv Modules ◽  
Interactive Map ◽  
The Impact

This article evaluates the impact of dust accumulation on the performance of photovoltaic (PV) modules in two different locations inside Egypt, Cairo and Beni-Suef. Two identical PV modules were used for that purpose, where each module was exposed to the outdoor environment in order to collect dust naturally for a period of three weeks, each in its corresponding location. The approximate dust density on each of the two PV modules was estimated. Moreover, the electrical performance was evaluated and compared under the same indoor testing conditions. The results show a better electrical performance and less dust density for the PV module located in Cairo compared to that located in Beni-Suef. The results further provide an indication for the impact of soling in different locations within the same country through a clear and simple procedure. In addition, it paves the way for establishing a Photovoltaic Soiling Index (PVSI) in terms of a Photovoltaic Dust Coefficient, as well as a Photovoltaic Dust Interactive Map. The product of such concepts could be used by the Photovoltaic systems designers everywhere in order to estimate the impact of dust on the future performance of PV modules in small and large installations in different regions around the globe, and during different times of the year as well.

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