Building Integrated Semitransparent Photovoltaic Thermal Research Articles

Effect of water flow on energy matrices and life-cycle cost analysis of urban BiSPVT system

The Energy Payback Time (EPBT) and Life-cycle Cost Analysis (LCCA) of a building integrated semi-transparent photovoltaic thermal (BiSPVT) system are carried out for different climatic and geographic zones. These two performance criteria are adversely affected by the shadow of the neighborhood’s buildings and obstacles. For countering the shadow effect, the BiSPVT system is proposed to install with optimum tilt and azimuth angle. The relative height, plan orientation, plan area, position, and horizontal distance of neighboring buildings are critical parameters in determining these angles to generate maximum energy. The proposed thermal model accurately calculates these angles and the output energy under various weather conditions at different places. The model assumes a water flow over the BIPV panel from an overhead tank, in view of increasing the efficiency of PV panel. The periodic nature of relevant parameters is considered in the thermal modeling of the BiSPVT system. The cost of energy produced by the proposed system ranges between 1.12 and 2.03 US$/ kWh depending on the climatic conditions of the place, and the EPBT of the system is found to be ranging between 11.6 years to 20.1 years which is lower than the expected service life (30 years) of the modules.

Effect of movable insulation on performance of the Building integrated Semi-transparent Photovoltaic Thermal (BiSPVT) system for harsh cold climatic conditions: a case study

ABSTRACT Semi-transparent photovoltaic modules are integrated with the building’s rooftop with the provision of movable insulation during off-sunshine hours to reduce the heat losses from room to the ambient. A significant rise in room air temperature of about 6°C at desired hours for cold climatic conditions of Srinagar, India was noted in this study. Also, a metallic drum filled with water has been placed inside the room to reduce the room temperature fluctuations, thus reducing the thermal load leveling. The study is also focused to analyse the simultaneous impact of natural ventilation, direct gain and daylight savings through the south-facing window, thus leading to daylight savings and reducing the dependency on artificial modes of illumination. The effect of water mass and packing factor has also been studied on electrical energy and daylight savings. Analytical expressions for water, metallic drum/tank, room, floor and solar cell temperatures have been derived.

Exergy, exergoeconomic and enviroeconomic analysis of a building integrated semi-transparent photovoltaic/thermal (BISTPV/T) by natural ventilation

Different parameters could contribute to the performance of Building Integrated Semi-Transparent Photovoltaic/Thermal (BISTPV/T) systems, for example amount of incident radiation, the location, the degree of semi-transparency of the PV system, orientation of the collector surface, and the mode of ventilation of the air within the double-skin façade (DSF). Nevertheless, the performance of the system could not be solely depended on energy efficiency but has to be analyzed in its entirety. Thus, exergy efficiency must be examined as well. The present work studies the exergy, exergoeconomic and enviroeconomic analysis of BISTPV/T system by natural ventilation. For a given meteorological conditions, the energy and exergy efficiency, net and ratio loss rate, CO2 emission and enviroeconomic reduction are calculated by solving a set of energy and exergy formulations. The results depicted that the BISTPV/T exhibits greater energy and exergy efficiency than the opaque BIPV/T, thus creating lower loss rate and eventually better impact economy and environment.

Movable insulation in building integrated semi-transparent photovoltaic thermal (BiSPVT) system

The BiSPVT system involves an integration of semi-transparent photovoltaic (SPV) modules with buildings along with the provision of harvesting thermal energy. The system generates electrical and thermal energy for the building as well as provides day-lighting. However, during summer season the production of thermal energy is higher and thermal demand is lesser as compared to winter season. Also, the higher thermal energy production is unfavourable for the generation of electrical energy by SPV modules. The use of movable insulation (MI) on glazed wall can be one of the method to reduce the thermal energy generation. In this paper, a thermal model has been developed for BiSPVT system and the effect of MI on thermal performance of the system is studied. The energy balance equations are obtained for the inclined SPV modules (top), reinforced cement concrete (RCC) floor (bottom), air of room (SPV modules, floor and four brick/glazed side walls). The room temperature and SPV cell temperature are derived as a function of a) climatic parameters (solar irradiance and ambient temperature), b) design parameters and c) heat transfer coefficients by using the energy balance equations. It is found that by using MI with less or no air cavity thickness, the temperature of room has reduced by 1.93°C. However, the effect of MI on SPV cell temperature is marginal. The proposed model can be utilized to evaluate cell and room temperatures for BiSPVT system installed at different places of the world provided solar irradiance and ambient temperature of that place are known.

Performance evaluation of 7.2 kWp standalone building integrated semi-transparent photovoltaic thermal system

A building integrated semi-transparent photovoltaic thermal (BiSPVT) system involves an integration of semi-transparent photovoltaic modules with buildings along with the provision to harvest thermal energy and provide daylighting. In this paper, a thermal model has been developed for a 7.2 kWp BiSPVT system to evaluate the yearly energy generation potential of the system. Through the experiments performed on the system with variation in number of air changes per hour (N) in its room, the efficacy of the model has been presented. It has been found that N creates negligible decrease in PV cell temperature whereas with N = 11 (day2) and N = 22 (day3), the maximum room temperature has been found to decrease by 1.3 °C and 1.9 °C respectively. Further, the efficiency of SPV array has been evaluated in real time i.e. with the array connected to balance of system (power conditioning unit (PCU), AC load, battery bank). The average efficiency of SPV array when loaded at maximum power point by the PCU is found to be 6.90%. The total energy generated in a year by the BiSPVT system is found to be 8927.1 kWh. Additionally, the impact of poor health of battery bank on electricity generation for standalone PV systems has been presented.

Parametric study to understand the effect of various passive cooling concepts on building integrated semitransparent photovoltaic thermal system

In this paper, parametric study has been conducted for a Building integrated Semitransparent Photovoltaic Thermal (BiSPVT) system with various passive cooling parameters like water mass (heat capacity), water flow (evaporative cooling) and daylighting in one model. Study has been conducted for both hot climatic conditions. Also, effect of each parameter on the system has been studied and illustrated on various temperatures, electrical energy and solar cell electrical efficiency. A comparative study has been conducted for 4 cases namely (a) BiSPVT system (b) BiSPVT system with water flow (c) BiSPVT system with heat capacity and (d) BiSPVT system with water flow along with heat capacity to understand the impact of each and every parameter on the BiSPVT system. It has been observed that case (d) offers maximum cooling when compared to other cases (with cases b, c and a respectively following it). A drop of 38.84 °C in peak room temperature is found in case (d) when compared to case (a). The paper also presents the best cases suited for thermal heating and thermal cooling purpose.

A thermal periodic theory and experimental validation of building integrated semi-transparent photovoltaic thermal (BiSPVT) system

Abstract In this paper, a thermal periodic theory of building integrated semi-transparent photovoltaic thermal (BiSPVT) system has been developed by using the basic energy balance equation for a semi-transparent photovoltaic roof; room air, brick/glazed walls and reinforced concrete cement (RCC) floor of the first room. Since solar irradiation and ambient air temperature are periodic in nature hence, all temperatures namely temperature of rooms, PV cell and floor will be periodic in nature. With the help of energy balance equations and periodic nature of all temperature, two 5 × 5 matrices namely time independent and time-dependent part of basic equations have been obtained. Two matrices were solved for unknown time independent and time dependent constants by using matrix inversion method for an experimental climatic data of Varanasi, India and design parameters of BiSPVT system. By using the known constants, the hourly variation of solar cell, air of rooms and floor temperatures have been computed. Further, the obtained theoretical results have been validated experimentally for the proposed BiSPVT system. It has been found that the maximum solar cell and room 1 temperatures are 67.64 °C and 44.6 °C respectively. Moreover, an effect of a number of air change (N), packing factor and thickness of (RCC) on room air temperature have been studied. Based on obtained results, it has been observed that there is (i) significant effect of the number of air change (N) for room 1 and (ii) marginal effect on room 2 room air temperature. Further, it has been observed that the optimum number of air change for room 2 (N2) is 3 and optimum thickness of RCC should be 0.3 m to minimize the room 2 temperature. The electrical DC energy produced by the proposed BiSPVT system with an effective area of PV roof as 88.66 m 2 is 14.55 kW h per day during typical day of experiment.

Effect of heat capacity on monthly and yearly exergy performance of building integrated semitransparent photovoltaic thermal system

In this communication, a building integrated semitransparent photovoltaic thermal (BiSPVT) system has been analysed, in which the effect of heat capacity has been studied by placing a water tank inside the room. The water tank helps in achieving better thermal comfort conditions. An analytical expression for water temperature, tank temperature, room air temperature, floor temperature, and the solar cell temperature of the BiSPVT system has been derived to evaluate the thermal load levelling (TLL), monthly thermal exergy, and yearly overall exergy, including natural day lighting. Numerical computations have been carried out for cold climatic conditions of Srinagar, India. Based on computations, the following conclusions have been drawn: The TLL decreases with an increase in the heat capacity (from 0 to 600 kg) by 20.39%. The exergy is minimum in December and maximum in June for all heat capacities of water mass. The thermal energy and electrical energy are the lowest in January. The electrical efficiency decreases by 8.3% with an increase in the water mass from 0 to 600 kg in January, and the average monthly thermal exergy and yearly overall exergy increase with an increase in the heat capacity of water mass.

Effect of Different Photovoltaic Materials on Energetic and Exergetic Performance of Photovoltaic Thermal Arrays

The study presents the effect of packing factor of Photovoltaic (PV) module on the room temperature, cell temperature and efficiency of a proposed Building Integrated Semi-transparent Photovoltaic Thermal (BiSPVT) and Building Integrated Opaque Photovoltaic Thermal (BiOPVT) systems with duct mounted on the roof of the building. Different PV materials like mono-crystalline silicon (m-Si), amorphous silicon (a-Si), poly-crystalline silicon (p-Si), cadmium telluride (CdTe), copper indium selenide (CIS) and hetero-junction with intrinsic thin layer (HIT) have been considered in the analysis under the cold climatic condition of India. Since Srinagar (India) has the cold climatic condition, therefore, its climatic data has been considered in the present analysis.

Exergy analysis of building integrated semitransparent photovoltaic thermal (BiSPVT) system

In this paper, an exergy analysis of building integrated semitransparent photovoltaic thermal (BiSPVT) system has been carried out. In the proposed system, the room below building integrated semitransparent photovoltaic thermal system has been considered as an air-conditioned (constant room temperature). Energy balance equation for each components namely semitransparent photovoltaic roof, floor and room air have been given. Based on energy balance, an analytical expression for room air, solar cell and room floor temperatures have been derived along with solar cell electrical efficiency. Further by considering the day lighting parameters, an overall exergy of the proposed system has been derived for different number of air change between the room and ambient air. It has been observed that there is reduction in room air and solar cell temperatures with an increase of number of air changes. However, solar cell electrical efficiency increases with decrease in temperature of solar cell. Further, it is found that an electrical power and illumination inside the room are more dominating in comparison with thermal exergy. An increase of 1.15% in an overall exergy is observed for the number of air changes varies from 0 to 4. Experimental validation of theoretical model has also been carried out.

Effect of packing factor on the performance of a building integrated semitransparent photovoltaic thermal (BISPVT) system with air duct

In this paper, an attempt has been made to study the effect of packing factor of semitransparent photovoltaic (PV) module integrated to the roof of a building, on the module and room air temperature, and electrical efficiency of PV module. Energy and exergy analysis have been carried out by considering different packing factors (0.42, 0.62, and 0.83) of PV module namely mono crystalline silicon (m-Si), poly crystalline silicon (p-Si), amorphous silicon (a-Si), cadmium telluride (CdTe), copper indium gallium diselenide (CIGS), and a heterojunction with thin layer (HIT). It is observed that the decrease in the temperature of PV module due to decrease in packing factor, increases its electrical efficiency. It is also found that the decrease in packing factor increases the room temperature. Maximum annual electrical and thermal energy is found to be 813kWh in HIT and 79kWh in a-Si PV module respectively with packing factor of 0.62.

Energy and exergy analysis of a building integrated semitransparent photovoltaic thermal (BISPVT) system

In this paper, a study has been carried out to evaluate the energy and exergy performance of a building integrated semitransparent photovoltaic thermal (BISPVT) system integrated to the roof of a room. Comparisons have been carried out on the basis of energy and exergy by considering six different photovoltaic (PV) modules. It is observed that maximum annual electrical energy is 810kWh for heterojunction comprised of a thin amorphous silicon (a-Si) PV cell on top of a crystalline silicon (c-Si) cell (also known as HIT) and the maximum annual thermal energy is 464kWh for a-Si. It is also concluded that HIT PV module is suitable for producing electrical power whereas a-Si is suitable for space heating. However, an annual overall thermal energy (2497kWh) and exergy (834kWh) is maximum for HIT PV module.

A Comparative Study for a Building Integrated Semitransparent Photovoltaic Thermal (BISPVT) System Integrated to Roof with and without Duct

In this paper, a study has been carried out to evaluate annual energy and exergy of a building integrated semitransparent photovoltaic thermal (BISPVT) system integrated to the roof of a building with and without duct. Comparisons of annual energy and exergy have been done by considering six different photovoltaic (PV) modules installed on the roof for cold climatic city of Srinagar, India. It is observed that the annual overall thermal energy is maximum for heterojunction with thin layer (HIT) and minimum for amorphous silicon (a-Si) for both with and without duct cases. It is also found that the annual overall exergy in HIT is 643 kWh and 610 kWh for both with and without duct cases, respectively.

A Comparative Study for a Building Integrated Semitransparent Photovoltaic Thermal (BISPVT) System Integrated to Roof with and without Duct

A Comparative Study for a Building Integrated Semitransparent Photovoltaic Thermal (BISPVT) System Integrated to Roof with and without Duct

Performance evaluation of a building integrated semitransparent photovoltaic thermal system for roof and façade

In this paper, analytical expressions have been derived for room air temperature of building integrated semitransparent photovoltaic thermal (BISPVT) and building integrated opaque photovoltaic thermal (BIOPVT) systems each integrated to the roof of a room with and without air duct. Comparative studies have also been carried out between BISPVT and BIOPVT system each integrated to the façade and roof of a room with and without air duct for the cold climatic conditions of Srinagar, India. However, the present thermal model is also valid for different climatic conditions. It is observed that there are maximum (18.0 °C) and minimum (2.3 °C) rise in room air temperature for semitransparent photovoltaic thermal (SPVT) roof without air duct and opaque photovoltaic thermal (OPVT) façade with air duct respectively. Further, on the basis of sensitive analysis, it is also observed that increase of air mass flow rate (0.85–10 kg/s) through duct increases the room air temperature from 9.4 to 15.2 °C for SPVT roof for a given climatic and design parameters.