International Journal of Electrical and Computer Engineering (IJECE) Vol.
No.
February 2019, pp.
ISSN: 2088-8708.
DOI: 10.
11591/ijece.
Review of solar photovoltaic/thermal (PV/T) air collector Ahmad Fudholi1.
Mariyam Fazleena Musthafa2.
Abrar Ridwan3.
Rado Yendra4.
Hartono5.
Ari Pani Desvina6.
Majid Khan Bin Majahar Ali7.
Kamaruzzaman Sopian8 1,2,8Solar Energy Research Institute.
Universiti Kebangsaan Malaysia.
Malaysia 3Prodi Teknik Mesin.
Fakultas Teknik.
Universitas Muhammadiyah Riau.
Indonesia 4,5,6Department of Mathematics.
Faculty of Science and Technology.
Universitas Islam Negeri Sultan Syarif Kasim (UIN Susk.
Indonesia 7School of Mathematical Sciences Universiti Sains Malaysia.
Malaysia
Article Info
ABSTRACT
Article history:
Growing concern with regard to energy sources and their usage has consequently increased significance of photovoltaic thermal (PV/T) A PV/T air collector is a system which has a conventional PV system combined with a thermal collector system.
The system is able to produce electrical energy directly converted from sunlight by using photoelectric effect.
Meanwhile, it also extracts heat from the PV and warms the fluid .
ir flo.
inside the collector.
In this review, solar PV system and solar thermal collectors are presented.
In addition, studies conducted on solar PV/T air collectors are reviewed.
The development of PV/T air collectors is a very promising area of research.
PV/T air collectors using in solar drying and solar air heater.
Received Jan 27, 2018 Revised Jul 4, 2018 Accepted Jul 27, 2018 Keywords:
Energy analysis Exergy analysis PV/T efficiency Renewable energy Copyright A 2019 Institute of Advanced Engineering and Science.
All rights reserved.
Corresponding Author:
Ahmad Fudholi.
Solar Energy Research Institute.
Universiti Kebangsaan Malaysia, 43600 Bangi Selangor.
Malaysia.
Email: a.
fudholi@gmail.
INTRODUCTION
Solar energy is the radiation produced as a result of the nuclear fusion reactions in the sun.
This energy is radiated from sun in all directions.
The solar energy from sun when beamed onto Earth for even an hour is sufficient to produce the global energy need for an entire year.
Many technologies exist to harness the energy from sun and use it in application.
The energy harnessed from sun can be used in two different forms.
thermal and electrical.
One such technology which utilizes radiation from solar energy to produce electrical and thermal energy is Solar PV/T technology and the device used in this technology is called a Solar PV/T Solar PV/T collector is a hybrid system that deploy solar PV technology and solar heater When a photovoltaic system is irradiated with solar energy, the cell temperature increases The greater the temperature difference between ambient temperature and temperature of the cell is, the less efficient the electrical efficiency and electrical output of the PV module becomes.
In order to enhance the electrical efficiency, this excess heat is extracted by passing a heat extracting fluid .
ir or wate.
under the module.
This integrated method, where electrical and thermal energy are generated simultaneously, is the basis of PV/T collectors .
The overall performance of the PV/T air collector can be evaluated based on the thermodynamic, environmental and economic impacts analysis.
Enviroeconomic and exergoeconomic analyses for PV/T air collectors was studied .
Energy-exergy-economic-environmental analyses for different PV/T array systems was studied .
In this review, thermodynamic aspect is focused involving exergy analysis.
Exergy has the characteristic that it is conserved only when all processes of the system and the environment are Journal homepage: http://iaescore.
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ISSN: 2088-8708
Exergy is destroyed whenever an irreversible process occurs when an exergy analysis is performed on a system like PV/T system, the thermodynamic imperfections can be quantified as exergy destruction, which is wasted work or wasted potential for the production of work.
By analyzing the exergy destroyed by each component in a process, it can be easily identified where the focus should be given to improve system efficiency.
Exergy analysis is conducted by utilizing the first and second law of Exergy analysis has become an essential tool in the system design, analysis, and optimization of thermal systems .
RESEARCH METHOD
The system which converts sunlight into electrical current by means of a photovoltaic (PV) cell is known as PV system.
The process by which the PV cell converts sunlight to electrical current is called Photoelectric effect.
Sunlight consists of photons.
Billions of these photons continues to hit the earth every These photons contain large quantities of energy corresponding to the different wavelengths of the solar spectrum.
When photons strike a PV cell, they are either reflected, absorbed, or passed through.
Electricity is generated by the photons that are absorbed.
The photons with energy greater than the band-gap energy of the semiconductor when absorbed creates some electron-hole pairs proportional to the incident irradiation.
When such a photon is absorbed, the energy of that photon is absorbed by an electron in an atom of the semiconducting material of the PV cell.
With the added energy, the electron can escape from its normal position .
alence ban.
in the atom to become free by jumping to the conducting band leaving a hole behind.
The electrical circuit is completed by the flow of these electrons and holes using electrodes.
As millions of photons hits the PV cell, millions of electrons gain energy and become free to move along the conducting wires.
Solar cells and modules consists of thin conducting wires and a built-in electric field to provide the voltage needed to move the current through an external load.
The small quantity of current produced at each cell can be significantly increased by connecting several cells together and kept on large .
The PV system may include major components as.
DC-AC power inverter, battery storage, system and battery controller, back-up energy sources and electrical loads .
The Figure 1 shows the main components of a Solar PV system.
PV cells are the basic unit which converts the sunlight to energy.
A PV
module consists of PV cells arranged in frame to form a module.
A PV module is constructed by connecting PV cells in series for high voltage and in parallel for high current.
By connecting series of PV modules, a PV array is formed.
The inverter is a device which converts direct current (DC powe.
into standard alternating Current (AC powe.
which can be used for the appliances in the home, synchronizing with utility power whenever the electrical grid is distributing electricity .
The charge controller regulates the flow of electricity from the PV modules to the battery and the It enables the battery to be fully charged without overcharging.
When the load is consuming power, the controller allows electricity to flow from the modules into the battery or the load.
When the battery is full the controller senses that and stops the flow of charge from the modules.
At night time, and/or if the demand exceeds the power produced from Solar PV during the day and battery, electricity is provided through utility power source.
The utility meter spins backwards when solar power production exceeds house demand.
This allows the user to credit any excess electricity in future utility bills .
The storage battery is used to store any excess energy produced by PV modules and deliver it back for consumption when in demand .
PV array Charge DC/AC Inverter Loads Battery Figure 1.
Schematic of PV system Generally.
PV systems can be classified based on their function and operational needs, their component configuration and the way other power sources and appliances are connected to the PV system.
There are three types of solar PV systems.
Stand-alone system or off-grid systems are systems which generate power and consume the power generated within the system and does not interact with the main electrical grid.
Review of solar photovoltaic/thermal (PV/T) air collector (Ahmad Fudhol.
A ISSN: 2088-8708 In a hybrid system, in addition to solar energy, one or more source of energy is hybridized in the solar PV system such as such as wind, biomass or diesel to provide the required power.
This increased the reliability and efficiency in a cost effective way .
SOLAR THERMAL COLLECTORS
A solar thermal collector converts solar energy into useful thermal energy which is then transferred to the working fluid flowing through the collector such as water and air.
The thermal energy collected can be used for various applications such a water or space heating, to generate steam.
It can also be stored in a thermal storage for later use.
Based on the working principle and other factors, solar thermal collectors can be categorized in various ways.
One of the common categorization is .
non-concentrating .
or example, flat plate collector.
or example, compound parabolic concentrator.
Another common way to categorize it is based on the working fluid .
eat transfer flui.
used inside the collector as heat extraction such as into liquid heating and air heating types.
For applications at low to medium temperature of about 100oC, the type of solar collectors that are usually used is stationary collectors which do not use solar tracking mechanism.
They are generally used for air and water heating applications.
Whereas concentrating collectors which use solar tracking system is commonly used for applications at medium to high temperature of about 200-2500oC such as solar thermal power generation and high temperature heating .
The main difference in the design of flat plate air collector from water collector is air plate collectors lack the flow tubes that are attached to the absorber plate.
The main parameter to enhance the performance of solar air collector is the heat transfer rate between the absorber surface and the flowing air.
order to achieve this objective, various modification have been proposed in the design and air movement in solar air collectors including the use of corrugated, finned absorbers and multiple-pass air flow configurations as shown in the Figure 2.
Figure 2.
Different air flow designs for solar air collectors The thermal efficiency of solar thermal collectors is a ratio of the useful thermal energy, ycE to the overall incidence irradiations, ya.
Where the heat collected by the flat plate air collector can be measured by result of average mass flow rate,A heat capacity of flowing medium, ya and a temperature difference of the medium at the collector inlet, ycN and outlet, ycN .
yuC Aya .
cN Oe ycN ) ycE ya ya Int J Elec & Comp Eng.
Vol.
No.
February 2019 : 126 - 133
Int J Elec & Comp Eng
ISSN: 2088-8708
SOLAR PV/T AIR COLLECTORS
In 1978.
Kern and Russel introduced the concept of PV/T collectors using water or air as a heat removal fluid.
As such PV/T collectors can be classified into three categories based on the type of working fluid used.
Namely.
PV/T water collector.
PV/T air collector, and PV/T water/air combination collector .
Due to the dual functions of a PV/T collector, this type of collectors maximizes the use of solar energy resulting in a higher overall solar conversion rate than that of solely PV or solar collector.
The PV cells composed of semiconductor material convert highenergy photons of incident solar radiation into electricity.
The lower energy photons are absorbed by the PV panel and generate heat within the cells .
The generation of heat within the cell reduces the efficiency of the cells.
The photovoltaic thermal (PV/T) technology extract a great percent of this heat and utilize it for practical applications.
The removal of heat from the cell and transferring it to the working fluid increases the electrical efficiency of the PV module while simultaneously producing hot fluid which can be used for thermal applications.
Since PV/T offers an improved method of utilizing solar energy, the overall efficiency of the system is higher.
The major advantages of using PV/T is as follows .
: .
It is dual-purpose: a system which can be used to produce thermal and electricity output, .
It has a wide application: the thermal output can be used for drying, heating and cooling .
esiccant coolin.
, .
It is flexible and efficient: the combined efficiency is always much higher than using two individual systems and is especially attractive when roof-panel spacing is limited, and .
It is practical and cheap: it can be easily integrated to building with minor modification.
Furthermore, by replacing the roofing material with the PV/T system, the payback period can be reduced.
Recently.
Fudholi et al.
studied theoretical and experimental of PV/T air collector with n-groove.
They reported that PV/T exergy efficiencies of were 12.
91% and PV/T energy efficiencies The thermal and PV efficiency was 21.
9% and 9.
34% respectively.
In 2016.
Hazami, et al.
studied theoretical and experimental of PV/T air collector using energy and exergy They reported that PV/T exergy efficiencies of was 14.
From energy analysis, the PV and thermal efficiency was 15% and 50% respectively.
Slimani et al.
studied theoretical and experimental of PV/T air collector for an indirect solar dryer.
They reported that PV, thermal and PV/T efficiencies were 5%, 70% and 90%, respectively.
Gholampour and Ameri .
studied energy and exergy analysis of PV/T flat transpired collectors based on theoretical and experimental study.
They reported that PV/T exergy efficiencies of was 8.
From energy analysis, the thermal and PV/T efficiency was 69.
9% and 55% In 2015.
Li, et al.
studied theoretical and experimental of PV/T air collector in the hot summer and cold winter zone.
They reported that PV, thermal and PV/T efficiencies were 11.
4%, 50%
7%, respectively.
Researchers .
studied experimental PV/T air collector.
Rajoria et al.
reported that PV and thermal efficiencies were 3.
1% and 12.
1% respectively.
Ahn et al.
reported that PV, thermal and PV/T efficiencies were 15%, 23% and 38% respectively.
Good et al.
reported that PV and thermal efficiencies were 17.
4% and 71.
5% respectively.
Amori and Abd-AlRaheem .
studied experimental .
of various PV/T air collectors.
They reported that PV and thermal efficiencies were 4% and 46-62% respectively.
In 2013.
Rajoria et al.
studied theoretical and experimental of PV/T air collector.
They reported that PV/T energy and exergy efficiencies of were 11.
3% and 16.
3%, respectively.
In 2012.
Agrawal et al.
studied theoretical and experimental of PV/T air collector connected in series.
They reported that PV and thermal efficiencies were 12.
4% and 35.
7% respectively.
Amori and Al-Najjar .
studied theoretical of thermal and electrical performance for PV/T air collector in Iraq.
They reported that PV, thermal and PV/T efficiency were 9-12.
3%, 19.
8% and 47.
6% respectively.
In 2010.
Agrawal and Tiwari .
studied energy and exergy analysis of PV/T air collector under cold climatic conditions.
They reported that PV/T energy efficiency was 53.
Sarhaddi et al.
studied energy and exergy analysis of PV/T air collector.
They reported that PV, thermal and PV/T efficiency were 10%, 17.
18 and 45% respectively.
PV/T exergy efficiency was 10.
Agrawal and Tiwari .
studied theoretical and experimental of PV/T air collector.
They reported that PV and thermal efficiency were 7.
54% respectively.
CONCLUSION
Based on the present review, the following conclusions can be drawn: .
A number of research have been done on PV/T air collectors over the last four decades, exploring aspects such as efficiency enhancements by design development, numerical simulation, prototype design, experimental testing and testing methodologies for PV/T air collectors.
The energy and exergy efficiency of PV/T air collector were 31% to 94% and 8.
7% to 18%, respectively.
The development of PV/T air collectors is a very promising area of research.
Today.
PV/T air collectors using in solar drying and solar air heater.
Review of solar photovoltaic/thermal (PV/T) air collector (Ahmad Fudhol.
A ISSN: 2088-8708
ACKNOWLEDGEMENTS
The authors would like to thank the UKM and UIN Suska Riau for funding (GP-K020.
and (GGP-2017-.
REFERENCES