renewable energy

Renewable and Sustainable Energy Reviews 16 (2012) 1383 1398

Contents lists available at SciVerse ScienceDirect

Renewable and Sustainable Energy Reviews

j ourna l h o mepage: www.elsev ier .com/ locate / rser

Advancement in solar photovoltaic/thermal (PV/T) hybrid collector technology

V.V. Tyaga Centre for Eneb Sardar Swara

a r t i c l

Article history:Received 29 AAccepted 19 D

Keywords:Thermal collecPhotovoltaic sPhotovoltaic/tEnergy converApplication of

Contents

1. Introd2. Solar thermal collectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1384

2.1. Flat plate collector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13842.2. Evacuated tube collector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13852.3. Concentrating collectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1385

2.3.1. Parabolic trough collector (PTC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13862.3.2. Linear Fresnel reector (LFR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1386

3. Solar 3.1.

4. Solar 4.1.

5. Novel6. Concl

AcknoRefer

CorresponE-mail add

1364-0321/$ doi:10.1016/j.2.3.3. Central receiver system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13872.3.4. Parabolic dish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1387

photovoltaic (PV) technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1387Types of solar cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13873.1.1. Silicon solar cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13883.1.2. III-V group solar cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13883.1.3. Thin lms solar cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13883.1.4. Dye-sensitized solar cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1389

PV/thermal hybrid technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1389Types for PV/thermal collector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13894.1.1. Liquid PV/T collector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13904.1.2. PV/T air collector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13924.1.3. PV/T concentrator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1393

applications of PV/thermal collector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1394usions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1397wledgement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1397

ences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1397

ding author. Tel.: +91 11 26596465.ress: [email protected] (V.V. Tyagi).

see front matter 2011 Elsevier Ltd. All rights reserved.rser.2011.12.013i a,, S.C. Kaushika, S.K. Tyagib

rgy Studies, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, Indian Singh National Institute of Renewable Energy Wadala Kalan, Kapurthala, Punjab 144610, India

e i n f o

pril 2011ecember 2011

torsystemhermal collector systemsion

PV/T systems

a b s t r a c t

This article presents an overview on the research and development and application aspects for thehybrid photovoltaic/thermal (PV/T) collector systems. A major research and development work on thephotovoltaic/thermal (PVT) hybrid technology has been done since last 30 years. Different types ofsolar thermal collector and new materials for PV cells have been developed for efcient solar energyutilization. The solar energy conversion into electricity and heat with a single device (called hybridphotovoltaic thermal (PV/T) collector) is a good advancement for future energy demand. This reviewpresents the trend of research and development of technological advancement in photovoltaic thermal(PV/T) solar collectors and its useful applications like as solar heating, water desalination, solar green-house, solar still, photovoltaicthermal solar heat pump/air-conditioning system, building integratedphotovoltaic/thermal (BIPVT) and solar power co-generation.

2011 Elsevier Ltd. All rights reserved.

uction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1384

1384 V.V. Tyagi et al. / Renewable and Sustainable Energy Reviews 16 (2012) 1383 1398

1. Introduction

Energy is considered a prime agent in the generation of wealthand a signicant factor in the economic development of any coun-try and the living standard of people. The importance of energyin economic development is recognized universally and historicaldata verify that there is a strong relationship between the availabil-ity of energy and economic activity. With the increasing demand ofenergy, today the world daily oil consumption is 85 million barrelsof crude oil [1]. Despite the well-known consequences of fossil fuelcombustion on the environment, this is expected to increase to 123million barrels per day by the year 2025 [2]. This is the main reasonfor pollution.

The greatest advantage of solar energy as compared with otherforms of energy that is environmental friendly and abundantlyavailable and can be supplied without any environmental pollution.Over the past century fossil fuels have been provided most of ourenergy needs because these are much cheaper and more convenientthan energy from alternative sources, and until recently environ-mental pollution has been of little concern. Hybrid systems for solar(renewable) energy utilization have attracted considerable atten-tion from scientists and engineers during the last decade because oftheir higher efciency and stability of performance in comparisonto individual solar devices. Traditionally, devices intended for usingsolar energy fall into two main classes depending on the methodof its conversion: either heat or electricity, like thermal collectorsand photovoltaic modules respectively.

Solar thermal energy collectors are special kind of heat exchang-ers that convert solar radiation into thermal energy through atransport msolar collecsolar systemthe incomitransfers itpurpose/apfor drying thtions in comof buildings

Photovoby directly cwhich are u

photoelectric effect are called solar cells. A photovoltaic systemconsists of solar cells and ancillary components. It converts the solarradiation directly into electricity. In 1954, researchers at the BellTelephone Laboratories demonstrated the rst practical conversionof solar radiation into electric energy by use of a pn junction typesolar cell with 6% efciency [3]. With the advent of the space pro-gram, photovoltaic cells made from semiconductor-grade siliconquickly became the power source of choice for use in satellites. Thecommon solar power conversion efciencies are between 15 and20% [4].

However, today a new area has emerged incorporating both themethods of energy conversion, which can be called photo thermo-conversion [5]. The solar energy conversion in to electricity andheat with a single device called hybrid photovoltaic thermal collec-tor (PVT). In this way, heat and power are produced simultaneouslyand it seems a logical idea to develop a device that can complywith both demands. A novel approach for research development inPVthermal system is described in this paper.

2. Solar thermal collectors

Solar energy collectors are special kind of heat exchangersthat transform solar radiation energy to internal energy of thetransport medium. There are basically two types of solar col-lectors: non-concentrating or stationary and concentrating. Anon-concentrating collector has the same area for intercepting andfor absorbing solar radiation, whereas a sun-tracking concentratingsolar collector usually has concave reecting surfaces to interceptand focus the suns beam radiation to a smaller receiving area,

y inc are e 1 [6rrenor (Fors.

at pla

ation s(less

ar colledium and/or moving uid. Classication of varioustors are illustrate in Fig. 1. The major component of any

is the solar collector. This is a device which absorbsng solar radiation, converts it into heat energy, and

through a uid (usually air, water, or oil) for usefulplications. Generally, they are used as air dryer/heatere agricultural products and/or heating/cooling applica-bination with the auxiliary heaters for air conditioning.ltaic (PV) is the most useful way of utilizing solar energyonverting it into electricity. Energy conversion devices,sed to convert sunlight to electricity by the use of the

thereblectorsin Tabltors cucollectcollect

2.1. Fl

Thecollectrange

Fig. 1. Classication of various solreasing the radiation ux. A large number of solar col-available in the market. A comprehensive list is shown]. In this section a review of the various types of collec-tly available will be presented. This includes at platePC), evacuated tube collector (ETC), and concentrating

te collector

plate collector (FPC) is the heart of any solar energyystem designed for operation in the low temperaturethan 60 C) or in the medium temperature range (less

ectors.

V.V. Tyagi et al. / Renewable and Sustainable Energy Reviews 16 (2012) 1383 1398 1385

Table 1Types of solar thermal collectors.

Motion Collector type Absorber type Concentration ratio Indicative temperature range (C)

StationaryFlat plate collector (FPC) Flat 1 3080Evacuated tube collector (ETC) Flat 1 50200Compound parabolic collector (CPC) Tubular 15 60240

Single-axis trackingLinear Fresnel reector (LFR) Tubular 1040 60250Parabolic trough collector (PTC) Tubular 1545 60300Cylindrical through collector (CTC) Tubular 1050 60300

Two-axes trackingParabolic dish reector (PDR) Point 1001000 100500Heliostat eld collector (HFC) Point 1001500 1502000

than 100 C). It is used to absorbed solar energy, convert it intoheat and then to transfer that heat to stream of liquid or gases.Flat-plate solar collectors, being mechanically simpler than con-centrating collectors, are mainly used for domestic and industrialpurposes [711]. The essential features of the conventional atplate collectors are:

(i) A at blackened absorbing plate (normally metallic) uponwhich the solar radiation falls and gets absorbed, thus changingto therm

(ii) Tubes, cplates toheat ene

(iii) Insulatiabsorbe

(iv) A transpreduce the abso

(v) A weathnents.

FPC is utracking oftowards thand north itor is equal1015 C mplate solar c

2.2. Evacua

The evaceffects of a of the absorciency comp

Fig.

above 80 C [12]. At present, the glass evacuated tube has becomethe key component in solar thermal utilization and they are provedto be very useful especially in residential applications for highertemperatures. So the evacuated solar collectors are widely usedto supply the domestic hot water or heating, including heat pipeevacuated solar collectors and U-tube glass evacuated tube solarcollectors [1318]. ETC use liquidvapor phase change materialsto transfer heat at high efciency. These collectors feature a heatpipe (a highly efcient thermal conductor) placed inside a vacuum-

tube. The pipe, which is a sealed copper pipe, attached to aopper n that lls the tube (absorber plate) is a metal tipd to the sealed pipe (condenser). The heat pipe contains amount of uid that undergoes an evaporating-condensingn this cycle, solar heat evaporates the liquid, and the vapor

to the heat sink region where it condenses and releases itsheat. The condensed uid return back to the solar collec-

the process is repeated. When these tubes are mounted,tal t

m of

ncen

centhoseon pquire

is opal energy.hannels or passages attached to the blackened absorber

circulate the uid required to remove the thermal orrgy from the plate.

on which is provided at the back and sides of ther plate to minimize conductive heat losses.arent cover (one or two sheets) of glass or plastic to

the upward convection and radiation heat losses fromrber plate.er tight container which encloses the above compo-

sually permanently xed in position and requires no the sun. The collectors should be oriented directlye equator, facing south in the northern hemispheren the southern. The optimum tilt angle of the collec-

to the latitude of the location with angle variations ofore or less depending on the application. A typical atollector is shown in Fig. 2.

ted tube collector

uated tube solar collectors (ETC) provide the combinedhighly selective surface coating and vacuum insulationber element so they can have high heat extraction ef-ared with at plate collectors in the temperature range

sealedblack cattachesmall acycle. Itravelslatent tor andthe mediagra

2.3. Co

Conthan tradiatially reenergy2. Cross-section and isometric view of at-plate collector.Fig. 3. Glass eevacuated tubips up, into a heat exchanger (manifold). A schematican evacuated tube collector is given in Fig. 3.

trating collectors

rating collectors provide energy at temperatures higher of at plate and ETC collectors. They re-direct solarassing through an aperture into an absorber and usu-

tracking of the sun. In concentrating collectors solartically concentrated before being transferred into heat.vacuated tube solar collector with U-tube. (a) Illustration of the glasse and (b) cross section.


Table 2Advantage and disadvantage of concentrating collectors.

S.no. Advantages Disadvantages

1. Thhicocosyenmthbe

2. It coacmletothhi

3. Thgrhere

4. Remsicococole

5. Owarcosevahecoec

Concentratiradiation bexhibits certhe convengiven in Tab

Concentand imaginat the receigory is the Cto the imag

Parabolic tLinear FresCentral recParabolic d

2.3.1. ParabThe rst

(PTC) goes ba Swedish imm2-aperturwas producsteam genesystems, buget applicatfor supplyinNeverthelesrefrigeratioconsumptiodetoxicaticannot be

Fig. 4. Parabolic trough collector (PTC).

ate collectors and evacuated tubes). On the other hand, user concentrating systems with high concentration ratios andmpe

Linea linelic trthe mlow rwer his sed ame working uid can achievegher temperatures in ancentrator system whenmpared to a at-platestem of the same solarergy collecting surface. Thiseans that a higherermodynamic efciency can

achieved.

Concentrator systems collectlittle diffuse radiationdepending on theconcentration ratio.

is possible with ancentrator system, tohieve a thermodynamicatch between temperaturevel and task. The task may be

operate thermoionic,ermodynamic, or othergher temperature devices.

Some form of tracking systemis required so as to enable thecollector to follow the sun.

e thermal efciency iseater because of the smallat loss area relative to theceiver area.

Solar reecting surfaces mayloose their reectance withtime and may require periodiccleaning and refurbishing.

ecting surfaces require lessaterial and are structurallympler than FPC. For ancentrating collector thest per unit area of the solarllecting surface is thereforess than that of a FPC.ing to the relatively small

ea of receiver per unit ofllected solar energy,lective surface treatment andcuum insulation to reduceat losses and improve thellector efciency areonomically viable.

(at plof solahigh-te

2.3.2. The

paraboabove many long to[21]. Tis sharon can be obtained by reection or refraction of solary the use of mirrors or lens. A concentrating collectortain advantages and disadvantages as compared withtional at-plate type collector [19] some of them arele 2.rating collectors can also be classied into non-imagingg depending on whether the image of the sun is focusedver or not. The concentrator belonging in the rst cate-PC whereas all the other types of concentrators belonging type. The collectors falling in this category are:

rough collector.nel reector.eiver.ish.

olic trough collector (PTC) practical experience with parabolic trough collectorack to 1870, when a successful engineer, John Ericsson,migrant to the United States, designed and built a 3.25-

e collector which drove a small 373-W engine. Steamed directly inside the solar collector (today called directration or DSG). From 1872 to 1875, he built seven similart with air as the working uid [20]. Nowadays, PTC tar-ion in which a solar eld can be successfully integratedg thermal energy at temperatures up to 250 C (Fig. 4).s, there are other applications, such as heat-drivenn and cooling, low-temperature heat demand with highn rates, irrigation water pumping, desalination andon. On the one hand, these temperature requirementsachieved by conventional low-temperature collectors

tal difcultof incomintion by adjby using athe absorbetors remotebesides a lanel reectoThe classic LThis prohibrature absorbers would be unnecessarily expensive.

r Fresnel reector (LFR)ar Fresnel reector (LFR) differs from that of theough collectors in that the absorber is xed in spaceirror eld (Fig. 5). Also, the reector is composed of

ow segments, which focus collectively on an elevatedreceiver running parallel to the reector rotational axisystem offers a lower cost solution as the absorber rowong several rows of mirrors. However, one fundamen-

y with the LFR technology is the avoidance of shadingg solar radiation and blocking of reected solar radia-acent reectors. Blocking and shading can be reducedbsorber towers elevated higher and/or by increasingr size, which allows increased spacing between reec-

from the absorber. Both these solutions increase costs,rger ground usage is required. The compact linear Fres-r (CLFR) offers an alternate solution to the LFR problem.FR has only one linear absorber on a single linear tower.its any option of the direction of orientation of a givenFig. 5. Linear Fresnel reector (LFR) collector.


reector. Sione can asstem. Therefreectors won to at leafor more detor inclinatibe position

2.3.3. CentrThe cent

large potento parabolicate steps beup to the hiabove 1000and huge ocycle (gas, ones emplorations for tcompletelycylindrical, heliostats aern hemispsurface. In ttower, and theat-transf

2.3.4. ParabA parab

point-focuslocated at axes. The dbeam into ttemperaturdistributed parabolic dParabolic-dpower conreceivers aconversion

3. Solar ph

Photovodirectly intoelectricity.

nduen sut disns thcell. ectrit intic syately

1024

tion ths

our p Laboadiatell wphot

becon so6]. H

cellse of saspe

cos

pes o

eral the ls its own quantities and drawbacks. The rst requirementFig. 6. Central receiver system.

nce this technology would be introduced in a large eld,ume that there will be many linear absorbers in the sys-ore, if the linear absorbers are close enough, individualill have the option of directing reected solar radiationst two absorbers. This additional factor gives potentialnsely packed arrays, since patterns of alternative reec-on can be set up such the closely packed reectors caned without shading and blocking solar radiation [22].

al receiver systemral receiver systems (Fig. 6) are considered to have atial for mid-term cost reduction of electricity compared

trough technology since they allow many intermedi-tween the integration in a conventional Rankine cyclegher energy cycles using gas turbines at temperaturesC, and this subsequently leads to higher efcienciesutputs [23,24]. Another alternative is to use Braytonturbines, which require higher temperature than theyed in Rankine cycle). There are three general congu-he collector and receiver systems. In the rst, heliostats

surround the receiver tower, and the receiver, which ishas an exterior heat-transfer surface. In the second, there located north of the receiver tower (in the north-here), and the receiver has an enclosed heat-transferhe third, the heliostats are located north of the receiverhe receiver, which is a vertical plane, has a north-facinger surface.

olic disholic dish reector, shown schematically in Fig. 7, is aing collector. Concentrating solar energy onto a receiverthe focal point of the dish, it tracks the sun in two

semicoit. Whsunlighelectroin the ates elsunlightovoltaFortuntic: 3 populathe earsatisfyphonesolar rsolar cgram, quicklycomm20% [2siliconvantagThese and low

3.1. Ty

Sevmake rial haish structure must track fully the sun to reect thehe thermal receiver. Parabolic-dish systems can achievees in excess of 1500 C. Because the receivers arethroughout a collector eld, like parabolic troughs,ishes are often called distributed-receiver systems.ish systems that generate electricity from a centralverter collect the absorbed sunlight from individualnd deliver it via a heat-transfer uid to the power-systems.

otovoltaic (PV) technology

ltaics (PV) comprise the technology to convert sunlight electricity. The term photo means light and voltaic,

A photovoltaic (PV) cell, also known as solar cell, is a

of a materimatching toand 1.7 eV. of charge cture, (ii) conreproducibduction, (viterm stabilisemiconduthe materiagroups:

Silicon so III-V grou Thin lmFig. 7. Schematic of a parabolic dish collector.

ctor device that generates electricity when light falls onnlight strikes a PV cell, the photons of the absorbedlodge the electrons from the atoms of the cell. The freeen move through the cell, creating and lling in holesIt is this movement of electrons and holes that gener-city. The physical process in which a PV cell convertso electricity is known as the photovoltaic effect. A pho-stem consists of solar cells and ancillary components.

the supply of energy from the sun to the earth is gigan-J a year, or about 10,000 times more than that the globalcurrently consumes. In other words, covering 0.1% ofsurface with solar cells with an efciency of 10% wouldresent needs [25]. In 1954, researchers at the Bell Tele-ratories demonstrated the rst practical conversion ofion into electric energy by use of a pn junction typeith 6% efciency [26]. With the advent of the space pro-ovoltaic cells made from semiconductor-grade siliconame the main power source for use on satellites. Thelar power conversion efciencies are between 15 andowever, the relatively high cost of manufacturing these

has prevented their widespread use. Another disad-ilicon cells is the use of toxic chemicals in manufacture.cts prompted the search for environmentally friendlyt solar cell alternatives.

f solar cell

different semiconductor materials have been used toayers in different types of solar cells, and each mate-al to be suitable for solar cell application is a band gap solar spectrum. The band gap should be between 1.1

The material must also have high motilities and lifetimearriers. Other requirements are (i) direct band struc-sisting of readily availability, (iii) non-toxicity, (iv) easy

le deposition technique, (v) suitable for large area pro-) good photovoltaic conversion efciency and (vii) longty The highest efciencies achieved using the differentctor materials are given in Table 3 [27]. Depending onl used solar cells can be categorized into three main

lar cells.p solar cells.s solar cells.


Table 3Best efciencies reported for the different types of solar cell.

Cell type Highest reportedefciency for small

Highest reportedmodule efciency

c-Si (crystall

Multi-c-Si

Si:H, amor

c-Si/Si:H

HIT cell GaAs cellInP cell GaInP/GaAs/

CdTe CIGS

Dye sensitiz

3.1.1. Silico3.1.1.1. Sining sunlighavailable fosolar cells ing becausthe potentihas receivesolar cells making it vvides cost-requirementemperaturhave reachecell module18%. Nowadand fabricatthan the higthe research

3.1.1.2. Polycrystal silicthose of tharies in pohence, redusion efciensilicon rangproduce poblocks of cais the ribbothin ribboncells. The mis the edgecrystalline can be cut iIt also has sments. Thecast and ribsurvey), slig

3.1.1.3. Amorphous silicon. Amorphous silicon is a non-crystallineform of silicon, i.e. its silicon atoms are disordered in structure.Amorphous silicon (a-Si) PV modules were the rst thin lm PVmodules commercially produced and presently the only thin lm

logyered bsor. Thes of aick fos lownufaergyre lo

cells

III-V . Gal

elemre sih levt, Galine irec

ells. T sufal. Thigh esistan whpplie ands PV s gros wh

. Indap ost Inrmalres wcy I

197area produced inthe laboratory

ine Si) 24.7% (UNSW,PERL)

22.7%(UNSW/Gochermann)

20.3% (FhG-ISE) 15.3%(Sandia/HEM)

phous Si 10.1% (Kaneka),N.B. single junction

Triple junction.Stabilizedefciency = 10.4%

(micro-morph cell) 11.7% (Kaneka),N.B. minimodule

11.7% (Kaneka),N.B. minimodule

21% (Sanyo) 18.4% (Sanyo)25.1% (Kopin) Not relevant21.9% (Spire) Not relevant

Ge multijunction 32% (Spectolab),N.B. 37.3% underconcentration

Not relevant

16.5% (NREL) 10.7% (BP Solarex)19.5% (NREL) 13.4% (Showa

Shell), N.B. forcopper galliumindium sulfurselenide

ed cell 8.2% (ECN) 4.7% sub-module(INAP)

n solar cellsgle crystalline silicon. Solar cells are capable to convert-t into electricity directly. Among the many materialsr solar cells, the most widely used semiconductor inis single-crystal silicon. Silicon is the most promis-e it is an abundant and safe raw material that hasal for high efciency performance. In particular, a-Sid much attention as a possible material for thin lmbecause of its superior optical absorption coefcient,iable for thin lms (cell thickness < 1/xm). a-Si also pro-effective fabrication because of its low raw materialts and low production energy requirements (depositione < 300 C). Today the best single crystal Si solar cellsd an efciency of 24.7% [28]. Commercial silicon solars are available with conversion efciencies as high asays lot of research work is going on the development

technodiscovlight) asiliconPV cellters thvariouthe maless encosts asilicon

3.1.2. 3.1.2.1of twostructuhas higsunlighcrystalhas a dsolar ccausesmateriably hhigh retems ispace adamagof GaAGaAs isystem

3.1.2.2band gThe rby thestructuefcienhalf ofed of single crystal ribbon silicon, which is lower in costh in quality, and these particular benet has motivateders in R&D for single crystal Si solar cells.

crystalline silicon. Consisting of small grains of single-on, polycrystalline PV cells are less energy efcient thane single-crystalline silicon PV cells. The grain bound-lycrystalline silicon, heddle the ow of electrons andces the power output of the cell. The energy conver-cy for a commercial module made of polycrystallinees between 10 and 14% [29]. A common approach tolycrystalline silicon PV cells is to slice thin wafers fromst polycrystalline silicon. Another advanced approachn growth method in which silicon is grown directly ass or sheets with the approach thickness for making PVost commercially developed ribbon growth approach-dened lm-fed growth (EFG). Compared to single-silicon, polycrystalline silicon material is stronger andnto one-third the thickness of a single-crystal material.lightly lower wafer cost and less strict growth require-

average price for a polycrystalline module made frombon is $3.92 per peak watt in 1996 (as per the literaturehtly lower than that of a single-crystal module [30].

InP based dof 22% for in literaturphotovoltaiimperfectiodevice efccannot be unicantly wthe materiathin cells cation coefcas unpromiIt was primdevelopmefor high conin the demgated again

3.1.3. Thin In a thin

is depositedplastic foil.ity than cry that has an impact on the overall PV markets. It was rstin 1974. A signicant advantage of a-Si is its high (sun-ptivity, about 40 times higher than that of single-crystalrefore only a thin layer of a-Si is sufcient for makingbout 1 m thick as compared to 200 or more microme-r crystalline silicon cells. Also, a-Si can be deposited on-cost substrates, including steel, glass and plastic, andcturing process requires lower temperatures and hence,

input. So the total material costs and manufacturingwer per unit area as compared to those of crystalline

[31,32].

group solar cellslium arsenide (GaAs). A compound semiconductor madeents: gallium (Ga) and arsenic (As), GaAs has a crystalmilar to that of silicon. An advantage of GaAs is that itel of light absorptivity. To absorb the same amount ofAs requires only a layer of few micrometers thick whilesilicon requires a wafer of about 200300 m thick. Itt band gap of 1.43 eV, nearly ideal for single junctionhe absorption coefcient of GaAs is relatively high andcient absorption of photons in only a few microns ofe rst AlGaAs/n-GaAs based solar cells with a reason-

fciency of 11% was reported by Alferov et al. [33]. Itsnce to heat makes the ideal choice for concentrator sys-ich cell temperatures are high. GaAs is also popular incations where strong resistance against solar radiation

high cell efciency are required. The biggest drawbackcells is the high cost of the single-crystal substrate thatwn on. Therefore it is most often used in concentratorere only a small area of GaAs cells is needed [34].

ium phosphide. Indium phosphide (InP) has a directf 1.34 eV, close to the optimum for solar conversion.P solar cells were homo junction devices produced

diffusion; however, subsequently a range of deviceas produced using different techniques. The rst high-

nP based devices were produced during the second0s [35]. The historical development of single junctionevices was reviewed in the 1989 [36]. An efciency

an InP crystalline solar cell has already been reportede [37]. The disadvantage of using III-V compounds inc devices is the very high cost of producing. Crystalns, including unwanted impurities, severely reduce theiencies and alternative lower cost deposition methodssed. These materials are also easily cleaved and are sig-eaker, mechanically, than silicon. The high density ofls is also a disadvantage, in terms of weight, unless veryn be produced to take advantage of their high absorp-ients. These drawbacks led to them being consideredsing materials for single junction, terrestrial, solar cells.arily due to their potential for space applications thatnt of III-V based devices was undertaken. The potentialversion efciencies together with radiation resistanceanding environment of space power generation miti-st the high materials cost [27].

lms solar cells-lm PV cell, a thin semiconductor layer of PV materials

on low-cost supporting layer such as glass, metal or Since thin-lm materials have higher light absorptiv-stalline materials, the deposited layer of PV materials is


Fig. 8. Operat

extremely teter (a singlayers of matechniques metal substusing up lestive approabe reducedpower to wrials revealewell as copfor the prodbeen establgeneration

3.1.4. Dye-sDye-sen

as a next-gelow manufavide a technpresent daycially availamaterials, wpreparation

3.1.4.1. Wotains broadwith transpusually TiO2conductor; counter eleplatine. Titafor the photwidely avaiciples of thabsorption sensitizer wthe semicoThe injecteto arrive atto the counturn regeneilluminationtovoltaic enon dye-senelectrodes wton to curre

the haze of the TiO2 electrodes, especially in the near infrared wave-length region. They found conversion efciency of 11.1%, measuredby a public test center. This indicates that raising the haze of TiO2electrodes is an effective technique for improvement of conversion

cy.

ar PV

Vthoducy bomandry, ity wit

the er israisinduleoverultacy away re atherllectoc-Si/glaze

or bpmet fewracti

ual-y andefcer thctives lims a wing ae sens;cheaildinng md.

erens, PVxt seing principles and energy level diagram of dye-sensitized solar cells.

hin, from a few micrometers to even less than a microm-le amorphous cell can be as thin as 0.3 m). Thinnerterial yield signicant cost saving. Also, the depositionin which PV materials are sprayed directly onto glass orrate are cheaper. So the manufacturing process is faster,s energy and mass production is made easier to attrac-ch of crystalline silicon. The conversion efciency may

but this would be more than balanced by the gain ineight ratio. A search for more suitable thin lm mate-d copper indium sulde, cadmium telluride (CdTe) asper indium diselenide (CuInSe2) and its related alloyuction of low cost thin lm solar cells and they haveished as the most promising candidates for the nextsolar cells [38].

ensitized solar cellssitized solar cells (DSCS) have been widely investigatedneration solar cell because of their simple structure andcturing cost. The dye-sensitized solar cells (DSCs) pro-ically and economically credible alternative concept to

pn junction photovoltaic devices. Up to now, commer-ble photovoltaic technologies are based on inorganichich require high costs and highly energy consuming

methods [39].

rking principle. The actual dye-sensitized solar cell con-ly ve components: (1) a mechanical support coatedarent conductive oxides; (2) the semiconductor lm,; (3) a sensitizer adsorbed onto the surface of the semi-(4) an electrolyte containing a redox mediator; (5) actrode capable of regenerating the redox mediator likenium dioxide TiO2 became the semiconductor of choice

efcien

4. Sol

A Ponly prthis wathe dementacompltion ofremindstrate the moogy recThe simefcienbetter

Themany otive co(c-Si/ptypes, dalonedevelothe pasThe att

it is dtricit

it is highattraing i

it haheaton thcatio

it is to burooperio

Diffsuch aThe neo-electrode due to its multiple advantages, i.e. low cost,lable, and non-toxic. Fig. 8 shows the operating prin-e dye-sensitized solar cell [40]. The rst step is theof a photon by the sensitizer, leading to the excitedhich injects an electron into the conduction band of

nductor, leaving the sensitizer in the oxidized state.d electron ows through the semiconductor network

the back contact and then through the external loadter electrode to reduce the redox mediator which inrates the sensitizer. This completes the circuit. Under, the device constitutes a regenerative and stable pho-ergy conversion system. Chiba et al. [41] investigatedsitized solar cells (DSCs) using titanium dioxide (TiO2)ith different haze. It was found that the incident pho-nt efciency (IPCE) of DSCs increases with increase in

the PV/ther

4.1. Types f

PV/thermPV/T domebuilding acfor both soland have recan be expeand can be

PV/T hasable for dombut also forduring wint/thermal hybrid technology

ermal (PVT) collector is a module in which the PV is noting electricity but also serves as a thermal absorber. Inth heat and power are produced simultaneously. Since

for solar heat and solar electricity are often supple- seems to be a logical idea to develop a device that canh both demands. Photovoltaic (PV) cells utilize a frac-incident solar radiation to produce electricity and the

turned mainly into waste heat in the cells and sub-g the temperature of PV as a result, the efciency of

decreased. The photovoltaic/thermal (PV/T) technol-s part of this heat and uses it for practical applications.neous cooling of the PV module maintains electricalt satisfactory level and thus the PV/T collector offers aof utilizing solar energy with higher overall efciency.re alternative approaches in PVT integration. Amongs, there can be selections among air, water or evapora-rs, monocrystalline/polycrystalline/amorphous silicon

a-Si) or thin-lm solar cells, at-plate or concentratord or unglazed panels, natural or forced uid ow, stan-uilding-integrated features, etc. A major research andnt work on the PVT technology has been conducted in

years with a gradual increase in the level of activities.ve features of the PV/T system are [42]:

purpose: the same system can be used to produce elec- heat output;

ient and exible: the combined efciency is alwaysan using two independent systems and is especially

in building integrated PV (BIPV) when roof-panel spac-ited;ide application: the heat output can be used both fornd cooling (desiccant cooling) applications dependingason and practically being suitable for domestic appli-

p and practical: it can be easily retrotted/integratedg without any major modication and replacing theaterial with the PV/T system can reduce the payback

t types of PV/thermal collector are being used presentlyT/air, PVT/water and PVT concentrated collector [43].ction of this review article is focus on development ofmal technology and application.

or PV/thermal collector

al devices can vary in design for various applications,stic hot water systems, PV/T for air heating system fortively cooled PV concentrators. The worldwide marketsar thermal and solar PV technology are growing rapidlyached a very substantial size. For PV/T a similar growthcted, since the technical feasibility is proven to be worthintegrated with other domestic applications.

broad range of applications, that is, it is not only suit-estic hot water heating such as glazed PV/T collectors,

commercial buildings like ventilated PV to preheat airer for room heating and to provide the driving force for


ater

natural vencirculation.on the typeuid (waterradiation. T

liquid PV/ air PV/T c PV/T conc

4.1.1. LiquiSimilar

PV/thermalneously eleapplicationcollectors ithermo-siptem a numbuses a photinside the cis shown in

Erdil et acomposed olector and tlocation in system occutrical energthis experimapproximata consideraheat, whichproposed hper day. Varules lead toloss, howevsumed by aperiod for tcost and thsystem eco

w etted cy a

durin as wter isve aisse eors terations d in cienith acy. TcoveFig. 9. Schematic diagram of a PV/T w

tilation during summer for thermal comfort/cooling/air There exist various forms of PV/T system, which depend

of PV module as well as its design, type of heat removal/glycol or air) and on the concentration of the incomingherefore, PV/T products can be classied as:

T collector;ollector;entrator.

d PV/T collectorto at plate collector water heating system, liquid

collectors are used to heat up the water and simulta-ctricity production for various domestic and industrials. The domestic water heater generally uses at platen parallel connection and run automatically with the

Chointegraefcien8.56% forcedthe latcan ser

Fracollectlow opconditselectecell efison wefciento the hon action whereas the industrial water heating sys-er of at plate collectors in series are used and hence, itovoltaic driven water pump to maintain a ow of waterollector. A schematic diagram of a PV/T water collector

Fig. 9.l. [44] did the experimental study on a hybrid system,f a photovoltaic (PV) module and a solar thermal col-ested for energy collection at a particular geographicalCyprus (Fig. 10). Normally, it is required to install a PVpying an area of about 10 m2 in order to produce elec-y of 7 kWh/day, consumed by a typical household. Inental study, they used only two PV modules of area

ely 0.6 m2 (i.e., 1.3 0.47 m2) each. PV modules absorbble amount of solar radiation that generate undesirable

may be utilized in water pre-heating applications. Theybrid system produces about 2.8 kWh thermal energyious attachments that are placed over the hybrid mod-

a total of 11.5% loss in electrical energy generation. Thiser, represents only 1% of the 7 kWh energy that is con-

typical household in the northern Cyprus. The pay-backhe modication is less than 2 years. The low investmente relatively short pay-back period makes this hybridnomically attractive.

ciency is 10cooling effelectors as aincluding ttovoltaic fua new concof collectorhot water incells. In thisematical mmetal absodetermine rate of watThe experimwhich weretem. Besidethe temperow rate ofmass ow rinuence omal losses ecollector. Ta given specollector.

al. [45] has presented an experimental study of facade-PV/T water-heating system and found the thermals 38.9% and the corresponding electrical efciency asg the late summer in Hong Kong. They compared bothell as natural mode of water circulation and found that

more preferable and suggested that this arrangements a water preheating system.t al. [46] studied the performance of water hybrid PV/To applied for direct solar oor type combine system. Itsing temperature level is appropriate for the operatingof the mono- or poly-crystalline photovoltaic modulesthat study. They concluded that the annual photovoltaiccy is 6.8% which represents a decrease of 28% in compar-

conventional non-integrated PV module of 9.4% annualhis is obviously due to a temperature increase relatedr. On the other hand, without a glass cover, the ef-

% which is 6% better than a standard module due to thect. Further research led to water hybrid PV/T solar col-

one piece component, both reliable and efcient, andhe thermal absorber, the heat exchanger and the pho-nctions. Assoa et al. [47] presented the development ofept of photovoltaic/thermal (PV/T) collector. This type

combines preheating of the air and the production of addition to the classical electrical function of the solar

work, a simplied steady-state two-dimensional math-odel of a PV/T bi-uid (air and water) collector with arber is developed. A parametric study is undertaken tothe effect of various factors including, the mass ower on the thermal performance of the solar collector.ental study carried out validates the simulated values,

used in conceiving the nal design of a prototype sys-s, the parametric study also predicated the variation ofature of cells and the uids as a function of the mass

water and air and the collector length. They found thatate of water in solar collector seems to have very littlen the solar air collector behavior. However, some ther-xist between the solar air collector and the solar waterhe solar collector performance study indicates that forcic collector length and mass ow rate of the uid,


Fig. 10. Structure of the hybrid syste

the thermathe coolingUsing furthis to be adathe productapplication

KalogiroPV/T solar stion. Whenfrom PV mtemperaturefciency asisting of pextraction uPatras as wincludes theof 4 m2 apewith a largeage tank. Thsystem empemploying is slightly loenergy andboth the thesion, it can b

Fig. 11. Paybatalline (p) and

asedstrensyste

like ari e

watIPVTrriedte c

ic parrmalnstanraturen cl ef

PVTS6 kg

hasafekybridch oc andven

menthat provl efciencies are able to reach approximately 80% and of the PV cells is satisfactory and can be improved.er simulation results they showed that the prototypepted for moderate temperature range appropriate forion of domestic hot water besides, some solar coolings.u and Tripanagnostopoulos [48] developed the hybridystems for domestic hot water and electricity produc-

properly designed, the PV/T systems can extract heatodules for water/air heating to reduce the operatinge of the PV modules and hence, to keep the electricalt a sufcient desired level. Hybrid PV/T systems con-c-Si and a-Si PV modules combined with water heatnits, were constructed and tested at the University ofell as simulated with the TRNSYS program. The work

study of two PV/T systems, one with a small scale unitrture area and 160 L water storage tank and another

scale system of 40 m2 aperture area and 1500 L stor-e results showed that the electrical production of theloying polycrystalline solar cells is higher than that of

the amorphous ones, but the solar thermal contributionwer. The derived TRNSYS results give an account of the

cost benets (Fig. 11) of the studied PV/T systems withrmosyphon and forced water ow. As a general conclu-e said that as the overall energy production of the units

is increis also of the water,

Tiwtion ofsolar ([46] caat placlimatall thethe cotempealso bethermatem (Iof 0.00system

Tounew happroaelectrithe conexperishow thas imck times of plain PV and thermosyphon PV/T systems with polycrys- amorphous (a) silicon cells.

tors. Dubeycovered aseries usingDC motor ttially coverand electricprimary reqcan be fullyrequirementhis type ofhouses in Dwater heate$ per annuannum, res

Fraisse ehybrid PV/(PV) modulframe and tm.

, the hybrid units have better chances of success. Thisgthened by the improvement of the economic viabilityms, especially in applications where low temperaturehot water production for domestic use, is also required.t al. [49] carried out the analytical study for the predic-er temperature of an integrated photovoltaic thermalS) water heater under constant mass ow rate. They

out the analysis using basic energy balance for hybridollector and storage tank, in the terms of design andameters respectively. It is observed that the daily over-

efciency of IPVTS system increases with increasingt mass ow rate of the circulating uid but collectione decreases. The exergy analysis of IPV/TS system hasarried out. It is further to be noted that the exergy andciency of an integrated photovoltaic thermal solar sys-) is maximum at the hot water withdrawal ow rate/s. The hourly net electrical power available from the

also been evaluated. et al. [50] presented the experimental study on a

photovoltaic thermal collector. They proposed a newf design, aiming to increase the energy effectiveness of

thermal conversion with lowest cost as compared totional hybrid collector technology already existing. Theal results approximately similar to the theoretical ones,the thermal performance of the new hybrid collectored as compared to the classic hybrid PVT solar collec- and Tiwari [51] evaluated the performance of partiallyt plate solar collectors for water heating connected in

theoretical modeling and a PV module is used to run theo circulate water. It is observed that the collectors par-ed by PV module combines the production of hot waterity generation and it is benecial for the users whoseuirement is hot water production while the collectors

covered by PV specially for the users whose primaryt is electricity generation. They have also found that if

system is installed only in 10% of the total residentialelhi (India) then the total carbon credit earned by PV/Trs in terms of thermal energy is about 44.5 millions USm and in terms of exergy it is 14.3 millions US $ perpectively.t al. [46] also studied the energy performance of waterT collectors (Fig. 12). The integration of photovoltaices in buildings allows one to consider a multifunctionalhen to reduce the cost by substitution of components.


Fig. 12. The glass covered water PVT prototype.

In order to limit the rise of the cell operating temperature, a pho-tovoltaics/thermal (PV/T) collector combines solar water heatingsystem and PV cells. The recovered heat energy can be used forvarious heating applications including water heating. In this study,the poly-crystalline photovoltaic modules of 16 m2 and 16 m2 ofsolar thermal collector were selected. They have also replaced twoconventionarea from 1

4.1.2. PV/T Air and w

tical PV/T ssystems resthose of PVproperties o(Fig. 13) arconstructioothers.

Aste et aPVT air collesloped roofwater proocollector arcovered by the entire gspacing betof solar radwich looks

Fig. 13. Schematic of the prototype pf PV/thermal air collector.

PV cells embedded. The simulation model, developed predicts quitewell the thermal and electrical performance of a PVT collector.

Tonui and Tripanagnostopoulos [54] worked for air-cooled PV/Tsolar collectors with low cost performance improvements. They

gated the performance of two low cost heat extractionemee higfcieded the P

is degreechieof thecal anpro

red.amoe dyovoltucin

The nt dtem,mentn pral collectors by one hybrid PVT collector with a varying6 to 32 m2.

air collectorater both have been used as heat transfer uids in prac-

olar collectors, yielding PVT/air and PVT/water heatingpectively. PVT/water systems are more efcient thanT/air systems [52] due to the high thermo-physicalf water as compared to air, However, PVT/air systemse utilized in many practical applications due to lown (minimal use of material) and operating cost among

l. [53] designed and performance evaluated of a hybridctor. They designed a PV module integrated in commons or vertical facades, replacing the external covering,ng and insulation layers. The schematics of the PVTe shown in (Fig. 14). The upper cover of system wasa glass sandwich type PV cells. The cell area can coverlazed surface or can be distributed in a grid where theween adjacent columns and rows can allow a direct gainiation to the backward absorber plate. The glass sand-like a chessboard composed of squares with or without

investiimprovachievtrical esuspennel in modelgood awere aeffect electriboth imcompa

Sukdict tha photfor redmates.desiccaing sysexperitem caFig. 14. Preliminary sketches of the PVT cnt modications in the channel of a PV/T air system toher thermal output and PV cooling so as to keep the elec-ncy at acceptable level. The use of thin at metal sheetat the middle or the nned back wall of an air chan-V/T air conguration has been suggested. A theoreticalveloped and validated against experimental data, wherement between the predicted results and measured dataved. The validated model was then used to study the

channel depth, channel length and mass ow rate ond thermal efciency, PV cooling and pressure drop forved and typical PV/T air systems and the results were

ngkol et al. [55] presented an experimental test to pre-namic performance of a condenser heat recovery withaic/thermal (PV/T) air collector to regenerate desiccantg energy use of an air conditioning room in tropical cli-system consists of ve main parts; namely, living space,ehumidication and regeneration unit, air condition-

PV/T collector, and air mixing unit. The results of this show that the thermal energy generated by the sys-oduce warm dry air as high as 53 C and 23% relativeollector.


humidity. Additionally, electricity of about 6% of the daily total solarradiation can be obtained from the PV/T collector in the system.Moreover, the use of a hybrid PV/T air heater, incorporated withthe heat recovered from the condenser to regenerate the desiccantfor dehumidsystem by a

Sarhaddformance othermal ansolar cell temature, openpoint voltamodel presecollector suimum powetc. Furtherefciency oelectrical, dsimulation ments. Theyand overall10.01% anddesign para

Hegazy tovoltaic/thhydraulic pthe air owII) and on bin a doubleeach modelmeasured cselectivity ohave been tional condother modecompared tpower, follothat the seletors due to at low owthe energy a(DEC) equipphotovoltaihumid climconducted fany heat sthourly simuTwo kinds olecture roomhandling unsidered andprimary enecollectors aferent systebeen descri(SAC) systebetter perfothe convencoupled wigures of mperformancsmall solar

4.1.3. PV/T Concent

temperatur

The sc and

d hearovide of Cant pell armored in

ful, whthmaoltaianc

hybrf soltratoells ae heexpeoltai, (c)measysteta actionratur

be k delig eleraturPC a

prodtic ewith, atollecor, th

(Fig colln hafcieetermecto

conventional solar thermal collector. On the other hand, the-saving efciency for PV/T collector with reectors in opti-sition is found to be 46.7%, which is almost equal to thel efciency of a conventional solar thermal collector. The-saving efciency of PV/T collector decreases slightly withar radiation intensity concentration factor.entry [61] designed a parabolic trough photovoltaic/thermalor with a geometric concentration ratio of 37 X at ANUlia as shown in (Fig. 17). The thermal and electrical efcien-the ANU CHAPS collector are shown under ideal conditions. Aication, can save the energy use of the air conditioningpproximately 18%.i et al. [56] investigated the thermal and electrical per-f a solar photovoltaic thermal (PV/T) air collector. Thed electrical parameters of a PV/T air collector include

perature, back surface temperature, outlet air temper--circuit voltage, short-circuit current, maximum powerge, maximum power point current, etc. The electricalnted can estimate the electrical parameters of a PV/T airch as open-circuit voltage, short-circuit current, max-er point voltage, and maximum power point current,more, an analytical expression for the overall energyf a PV/T air collector is derived in terms of thermal,esign and climatic parameters. The results of numericalshow good agreement with the experimental measure-

found that the thermal efciency, electrical efciency energy efciency of PV/T air collector is about 17.18%,

45%, respectively, for a typical climatic, operating andmeters.[57] made the overall performance of at plate pho-ermal (PV/T) air collectors for thermal, electrical andarameters. Four popular designs were considered withing either over the absorber (Model I) or under it (Modeloth sides of the absorber in a single pass (Model III) or

pass (Model IV). Heat balance equations written for have been solved numerically, incorporating/using thelimate data. The effects of air specic ow rate and thef the absorber plate and PV cells on the performancesexamined. They [54] found that under similar opera-itions, Model I has the lowest performance, while thels exhibit better thermal and electrical output gains aso Model I. Nevertheless, Model III demands the least fanwed by Models IV and II respectively. They also showedctive properties are inappropriate for these PV/T collec-the reduction in the generated energy by PV, especially

rates. Beccali et al. [58] presented a detailed analysis ofnd economic performance of desiccant cooling systemsped with both single glazed standard air and hybridc/thermal (PV/T) collectors for applications in hot andates. They showed the detailed results of simulationsor a set of desiccant cooling systems operating withoutorage. System performance was investigated throughlations for different systems and load combinations.f building occupations were considered, viz. ofce and. Moreover, three congurations of solar-assisted air

its (AHUs) equipped with desiccant wheels were con- compared with standard AHUs, focusing on achievablergy savings. The relationship between the area of solarnd the specic primary energy consumption for dif-m congurations and building occupation patterns hasbed. An outcome of their work is that solar air-coolingms equipped with PV/T collectors are shown to havermance in terms of primary energy saving than that oftional systems fed by vapor compression chillers andth PV cells. All solar air-cooling systems present gooderit for the primary energy consumption but the bestes is seen in systems with integrated heat pumps andcollector areas.

concentratorrating photovoltaic (CPV) systems can operate at higheres than those of the at plate collectors. Collecting the

Fig. 15. with CPC

rejectetem, pThe ussignicsolar ctor for worketems toenergy

Hjophotovperformof the array oconcensolar cimprovof the photovsystemspeed ment sthe daproductempeshouldshouldimizintempePV/T, Cpower

Koslector energyPV/T ccollectsystemof PV/Tpositiototal ebeen dout refor theenergymal pothermaenergythe sol

CovcollectAustracies of hematic model of a double-pass photovoltaic thermal solar collectorns.

t from a CPV system leads to a CPV/thermal (CPV/T) sys-ing both electricity and heat at medium temperatures.PV/T in combination with concentrating reectors has aotential to increase the power production from a givenea. Presently, research is going to develop CPV/T collec-

electricity as well as heat generation. Few authors havethis direction enabling the multipurpose hybrid sys-ll the increasing demand of both electrical and thermalile protecting the environment.n et al. [59] designed and fabricated a double-passc thermal solar air collector with CPC and studied thee over a range of operating conditions. The absorberid photovoltaic/thermal (PV/T) collector consists of anar cells for generating electricity, compound parabolicr (CPC) to increase the radiation intensity falling on thend ns attached to the back side of the absorber plate toat transfer rate to the owing air. The basic componentsrimental setup are as follows (Fig. 15). (a) Double-passc/thermal solar collector, (b) the air ow measurement

the temperature measurement system, (d) the windurement system, (e) the current and voltage measure-m, (f) the solar radiation measurement system and (g)quisition system. The results showed that electricity

in a PV/T hybrid module decreases with increasing thee of the airow. This implies that the air temperatureept as low as possible. On the other hand, the systemver hot air for other purposes. A trade off between max-ctricity and production of hot air at reasonable highes is thus necessary. The simultaneous use of hybridnd ns have a potential to signicantly increase theuction and reduce the cost of photovoltaic electricity.t al. [60] designed the optimal orientation of PV/T col-

reectors. In order to get more thermal and electrical reectors for solar radiation have been mounted ontor. To obtain higher solar radiation intensity on PV/Tey designed reectors with the movable PV/T collector. 16). In this work, the thermal and electrical efciencyector without reectors and with reectors in optimalve been calculated. Using the experimental results, thency and energy-saving efciency of PV/T collector haveined. Energy-saving efciency for PV/T collector with-

rs is found to be 60.1%, which is signicantly higher than


Fig. 16. (a) Scdiagram of the

comparisonthat the CHnear ambieincrease in due to the typical opecal efcienctherefore aenough.

Kribus etovoltaic (Msystem is untricity and a(PV/T) collelow-tempewide rangefor water h

process heat. An analysis of the system performance has shownthat at elevated temperatures, the electrical efciency is some-what lower, but most of the lost electricity is recovered as thermalenergy. The MCPV system is suitable for installation close to a con-sumer wheas, electriciapproach henergy with

5. Novel ap

PV/thermcations sucsolar still, psystem, bucollector. Ddiscussed a

Mittelmtrating phocombined mance CPVthermal eneof tempera

mentic aratureful tionbsor

VT codiffeide rableions,at ofoolinigni.telm

phohematic diagram of the cross section of PV/T collector. (b) Schematic PV/T collector with solar radiation reectors.

was made with a at plate thermal collector that showsAPS collector has a lower efciency at temperaturesnt (due to optical losses). It does not suffer the rapidthermal losses as the operating temperature increases,much reduced surface area. Measured results underrating conditions showed that the thermal and electri-ies are found to be around 58% and 11% respectively,

combined efciency of 69% which is signicantly high

t al. [62] analyzed a novel miniature concentrating pho-CPV) system. A miniature concentrator PV/thermalder development, producing about 140180 W of elec-n additional 400500 W of heat. Unlike the PV/thermal

requiredomestempeeral usproduceffect athe CPunder ably wcompaconditthan thsolar cto be ssystem

Mittratingctors, the heat from an MCPV collector is not limited torature applications. The later system can operate over a

of temperatures, and provide thermal energy not onlyeating, but also for cooling, desalination, and industrial

Fig. 17. Prototype CHAPS collector at the ANU.

system prowaste heat indicate thsolar-drivetional reverthe economelectricity ilectors is lodened in the acceptaachieve in led to resula potential ate under mThe main cof electricitpractical intion approaplant is usurange, i.e., wof the conv

Nayak afor the predcollector innology, Delre there is a need for multiple forms of energy suchty, heat and cooling. The results showed that the newas promising prospects in the increasing demand of

clean development.

plications of PV/thermal collector

al collector has good potential for some other appli-h as solar cooling, water desalination, solar greenhouse,hotovoltaicthermal solar heat pump/air-conditioningilding integrated photovoltaic/thermal (BIPVT) solarevelopments in the PV/thermal collector system ares below.an et al. [63] designed a solar cooling with concen-tovoltaic/thermal (CPVT) systems. They presented aheat and power approach that employs high perfor-T technology in order to produce both electricity andrgy at low or medium temperatures. The possible range

tures have been found to be wide enough to satisfy thets of several attractive thermal applications for bothnd industrial use. The CPVT collectors may operate ates above 100 C, and the thermal energy can drive sev-processes such as refrigeration, desalination and steam. The performance and cost of a CPVT system with singleption cooling are investigated in detail. They coupled tollectors, a single effect absorption chiller, was analyzedrent scenarios. The results show that under a reason-range of conditions, the CPVT cooling system can be

in costs to a conventional cooling system. Under some the solar cooling is even signicantly less expensive

the conventional cooling system. This is in contrast withg using solar thermal collectors, which is usually foundcantly more expensive than the conventional cooling

an [64] designed the desalination with the concen-tovoltaic/thermal (CPVT) systems also. The combinedduces solar electricity and simultaneously exploits theof the photovoltaic cells to desalinate water. The resultsat this approach can be competitive relative to othern desalination systems and even relative to conven-se osmosis (R.O.) desalination. The result depends onic conditions, and is valid when the prevailing price ofs high enough, and the installed cost of the solar col-w enough. The cost target for the solar collectors wasthe suitable conditions, which lies comfortably withinble range which the CPVT developers would like tothe near future. Some of the economic scenarios havets of zero cost of the desalinated water. This indicatesfor highly protable cogeneration plants that can oper-arket conditions without any incentive government.

onclusion is then that the cost-effective cogenerationy and desalinated water is feasible, and may become

the near future. A comparison of several solar desalina-ches has shown that R.O. with solar electricity from a PVally one of the best solar options in the non-competitivehere solar desalination is still more expensive than that

entional desalination.nd Tiwari [65] describe the energy and exergy analysisiction of performance of a photovoltaic/thermal (PV/T)tegrated with a greenhouse at Indian Institute of Tech-hi, India. The analysis was based on quasi-steady state


Fig. 18. Photo

condition. Ethe period fof the systeical day onthe same pecell, back suimately equmeasured vperatures hpercent devcient (0.95Exergy analtem showedTiwari [66] dation of a h(Fig. 18) coninclined at an area of in series wigalvanized used to incrthe FPC is aat its lowercirculation.

Fang et performancconditioninevaporationcient of perthe water tethe photovefciency hthat the me(PV/T) solaand can enphotovoltaipump/air-cperature in that the phsystem hasuseful and pgases, enab

Chow etKong. They(PV-SAHP)

Schemstem

oltaistainsysteaverrgy tion

the er timuld rnthltivelye thanstanype ial apersoollecg inen th. Thisstingd tharmare, ah thre, iaterises iial tot thethan

reduidssograph of experimental setup of hybrid (PVT) active solar still.

xperiments have been conducted extensively duringrom June 2006 to May 2007, for the annual performancem. The numerical computation was carried out for typ-ly for validation the experimental result obtained forriod. They observed that the theoretical value of solarrface and greenhouse room air temperatures is approx-ivalent to the experimental values. The predicted andalues of solar cell, back surface and greenhouse air tem-ave been veried in terms of the root mean square ofiation (7.0517.58%) as well as the correlation coef-0.97) and both exhibit a fair agreement between them.ysis calculations of the PV/T integrated greenhouse sys-

the second efciency of approximately 4%. Rahul andalso carried out the experimental and theoretical vali-ybrid (PVT) active solar still. The experimental set upsists of a single slope solar still of basin area 1 m 1 m

30 connected with two at plate collectors (each with1 m 2 m, inclined at 45). These FPCs are connectedth a total effective area of 4 m2 by using an insulatediron pipe of diameter 1.25 cm. A at plate collector isease the temperature of water in the solar still. One oflso integrated with a PV module (glassglass) of 75 W

temperature zone to run a DC motor used for water

al. [67] did an experimental study on the operatione of a photovoltaicthermal solar heat pump/air-g system. The performance parameters, such as the

pressure, the condensation pressure and the coef-

Fig. 19. SAHP) sy

photovas a suposed yearly-the eneconvena year,summCOP cothe morespecbe morand coin all tpotent

Andsolar cbuildinhas bemodelthe teshowethe thestructuon botthermocost mdecreapotentattic arather would

Dav

formance (COP) of heat pump/air-conditioning system,mperature and receiving heat capacity in water heater,oltaic (PV) module temperature and the photovoltaicave been investigated. The experimental results showedan photovoltaic efciency of a photovoltaicthermalr heat pump/air-conditioning system reaches 10.4%,hance 23.8% in comparison to that of a conventionalc module. On the other hand, the mean COP of heatonditioning system may attain 2.88 and the water tem-water heater can increase to 42 C. These results indicateotovoltaicthermal solar heat pump/air-conditioning

better performances can work with stability for suchotential applications, here by reducing the green houseling a clean environment.

al. [68] designed a PVT heat pump system for Hong proposed a photovoltaic-integrated solar heat pumpsystem, which can be seen as a scientic merge of the

integrated constructedin a windowsolar electrition to focuthe possibiinto the bulosses throuand hot wthe yearly shading of texcluded. Tpassive, up has been csolar windowindow buof Sweden.atic diagram of the photovoltaic-integrated solar heat pump (PV-.

c/thermal and solar assistant heat pump technology,able alternative (Fig. 19). It was found that the pro-m with R-134a as the refrigerant is able to achieve anage COP of 5.93 and PV output efciency of 12.1%. Thus,output is therefore considerably higher than that of theal heat pump plus PV side-by-side system. WithinPV-SAHP system would have a better performance ine from May to October, when the monthly average

each up to 6 or higher. In July as compared to January,y average values of COP were found to be 6.89 and 5.05. The amount of hot water produced in summer couldn double of that in the winter. As there is a continuoust demand of hot water in Hong Kong through the yearof building, and hence, the PV-SAHP system has theplications.n et al. [69] integrated photovoltaic/thermal (BIPVT)tor with building. In this study, the design of a noveltegrated photovoltaic/thermal (BIPVT) solar collectoreoretically analyzed using a modied Hottel-Whillier

model was validated with the experimental data from facility on a prototype BIPVT collector. The resultst the key design parameters such as the n efciency,l conductivity between the PV cells and their supportingnd the lamination method had a signicant inuencee electrical and thermal efciency of the BIPVT. Fur-t was shown that the BIPVT could be made of lowerals, such as pre-coated color steel, without signicantn efciency. Finally, there appears to be a signicant

utilize the low natural convection heat transfer in the rear of the BIPVT system to act as an insulating layer

using additional insulation material. The use of such airce the material cost of such a system to be signicantly.n et al. [70] developed and evaluated a building-multifunctional PV/T solar window, which is

of PV cells laminated on solar absorbers placed behind the glazing (Fig. 20). To reduce the cost of thecity, tiltable reectors were introduced in the construc-s radiation onto the solar cells. The reectors renderlity of controlling the amount of radiation transmittedilding. The insulated reectors also reduce the thermalgh the window. A model for simulation of the electricater production was developed which can performenergy simulations for different features, such as thehe cells and/or effects of the glazing can be included orhe simulation can be run with the reectors in an active,right and horizontal positions. The simulation programalibrated against the measurements on a prototypew placed in Lund, south of Sweden and against a solarilt into a single family house at Solgarden, central part

The results from the simulation showed that the solar


Fig. 20. (a)

window anunit cell are

Nagano thermalphincorporatepermit mobuilding apFig. 21. Solain the air galation of thof both thecollection cof the expesome of the

1. Six variaphous owithout

2. The avertion at a11.2% anpolycryswallboar

3. The averprojectedfrom 20.229.2% to the ambifor a stru Solar window at Lund in the south of Sweden. (b) Left: the prototype solar window; right: the solar window in Solgarden, Sweden with closed reectors.

nually produces about 35% more electric energy pera as compared to a vertical at PV module.

et al. [71] developed the experimentalotovoltaic (PV) hybrid exterior wallboards that

of PV cells. The clapboard-shaped hybrid wallboardsdular assembly that can be more easily adapted forplications than previous PV systems as can be seen inr heat is collected in the form of heated air circulatingp between the hybrid wallboard and the thermal insu-e exterior walls. These work presented an evaluation

electrical power generating ability and the solar heatapacity during winter with the six different variationsrimental (thermalPV hybrid wallboard) system andm are given as below:

tions of this wallboard were made using either amor-r polycrystalline silicon PV modules, either with ora glass plate enclosing the front face of the wallboard.age conversion efciency based on the solar radia-n inclination angle of 80 and the total cell area ofd 11.4% for wallboards PV3 and PV5, respectively:talline silicon modules and no glass plate covering thed.age thermal collector efciency based on perpendicular

wall area and vertical global solar radiation ranged% to 22.3% for wallboards without glass covers and from36.9% for those with glass covers at 0 C temperature ofent air. These efciencies were found to be satisfactorycture as simple as this hybrid wallboard.

Fig. 21. (a) System concept of new type PV/T hybrid wallboard. (b) Six types ofthermalPV hybrid wallboards.


6. Conclusions

The present work is an overview of a rigorous study carried outby number of authors for the last 30 years, in the area of design,developmecombinatiofor differenvoltaic/therextraction uously providenergy conva simple phand new mrenewable tricity and future ener(PVT).

The demand differesolar greenhigh demahybrid PV/Tdemand foof developmapplicationdesalinationsolar heat ptovoltaic/thby differenpotential omultipurpo

In hot coavailability Thus, by plvoltaic (PV)at the sametime, the sothrough theproductive can be coolthermal collized in an the ow rat

As a genePV/T collectsteps have bmore compincreased thwork shoultors and cocompetitive

Acknowled

One of thassistance iDelhi, India

References

[1] http://ww[2] www.wo[3] Zondag H

Developm Contrac2006.

[4] Chapin D

[5] Grant CD, Schwartzberg AM, Smestad GP, Kowalik J, Tolbert LM, Zhang JZ.Journal of Electroanalytical Chemistry 2002;522:40.

[6] Kalogirou SA. Solar thermal collectors and applications. Progress in Energy andCombustion Science 2004;30:23195.

[7] Nayak JK, Amer EH, Deshpande SM. Comparison of three transient meth- for te0;41:bolin

te andons. Sas D, Bte colltlundte solaente Fl colleg HP,r ene3;23(

Y, d tube7;32:

JT, Ass vaceat a

H, Kiss vaceat ah LJ, F

all dh LJ, Flector.

SY, Tcuatermopogiroueristic4;47:nandelectors0;14:ls D. 4;76:ls D, Merpla

warzbe cyclewablvez JMeratiolag; 1tzel M1].

L, Wte dye73.es RW-art ce

Charo J. Reroces

ar Cellmannterialsdamee, 199loni Rat AR2;6:2rov Zicondki K, stics o1;66:gner 5;26:tts TJ. 3. Lonrd JS, E PV sh AV, ds. Sotzel Mgy C: Peerudrviewnt, fabrication, and experimental evaluation of variousns of the photovoltaic/thermal (PVT) hybrid technologyt useful and applied application. The hybrid photo-mal (PV/T) systems consist of PV modules and heatnits mounted together. These systems can simultane-e electrical and thermal energy, thus achieving a higherersion rate of the absorbed solar radiation than that ofotovoltaic system. Different types of thermal collectoraterial for PV cells have been developed for efcientenergy utilization. The solar energy conversion in elec-heat with a single device is a good advancement forgy demand called hybrid photovoltaic thermal collector

and of heat and electricity are needed in industriesnt application, i.e. solar cooling, water desalination,house, solar still and solar heat pump. Industries shownd of energy for both heat and electricity and the

systems could be used to meet the increasing energyr these requirements. This article gives the trendsent and technological advancement for the useful

s of PV/T of hybrid systems, like solar cooling, water, solar greenhouse, solar still, photovoltaicthermalump/air-conditioning system, building integrated pho-ermal (BIPVT) solar collector and so on. The work donet researchers in this area shows that there is a hugef new and hybrid solar energy devices for useful andse applications.untries, PV cells are suffering to low efciency due nonof low ambient temperature for cooling the PVC system.acing a solar thermal collector behind a solar photo-

array, the PV cells can be cooled up some extent and time the heat produced by a PVC system. At the samelar collector can harvest most of the energy that passes

array that would otherwise be lost, recovering it forand useful applications. In this scenario, the PV cellsed by circulating uid like water or air within the solarlector and hence, the heat produced by PVC can be uti-optimum operating temperature range by controllinge of the cooling medium/circulation uid.ral conclusion, it is clear from the literature review thators are very promising devices and that no substantialeen taken towards reducing their cost and making themetitive. The overall energy production of the units ise hybrid system have better chances of success. Future

d be focus to improvement the efciency of PV/T collec-st reduction, through this achievement, it will be more

collector device.

gement

e authors (VV Tyagi) highly acknowledges the nancialn the form of Research Associateship due to CSIR, New.

w.nationmaster.com/graph/ene oil con-energy-oil-consumption.rldwatch.org., Bakker M, Van Helden W. PVT Roadmap/An European Guide for theent and Market Production of PVThermal Technology, PV Catapultt No. 502775 (SES6). Energy Research Centre of the Netherlands ECN;

M, Fuller CS, Pearson GL. Journal of Applied Physics 1954;25:676.

ods200

[8] Zampladiti

[9] Rojpla

[10] Vespla

[11] Ardma

[12] Garsola198

[13] Kimate200

[14] Kimglain H

[15] Hanglain H

[16] Shafrom

[17] Shacol

[18] YanevaThe

[19] Kalact199

[20] Fercol201

[21] Mil200

[22] Milpow

[23] Schbinren

[24] ChagenVer

[25] Gra200

[26] Binsta549

[27] Miltheand

[28] Zhain pSol

[29] HerMa

[30] Funtut

[31] Gal[32] Gob

196[33] Alfe

Sem[34] Ara

teri200

[35] Wa197

[36] Couvol

[37] WaIEE

[38] Shatren

[39] Grolo

[40] NazOvesting solar at-plate collectors. Energy Conversion & Management677700.

E, Del Col D. Experimental analysis of thermal performance of at evacuated tube solar collectors in stationary standard and daily con-olar Energy 2010;84:138296.eermann J, Klein SA, Reindl DT. Thermal performance testing of at-ectors. Solar Energy 2008;82:74657.

J, Ronnelid M, Dalenback JO. Thermal performance of gas-lled atr collectors. Solar Energy 2009;83:896904., Beccali G, Cellura M, Brano VL. Life cycle assessment of a solar ther-ctor. Renewable Energy 2005;30:103154.

Chakravertty S, Shukla AR, Agnihotri RC, Indrajit. Advanced tubularrgy collectora state of the art. Energy Conversion and Management3):15769.Seo T. Thermal performances comparisons of the glass evacu-

solar collectors with shapes of absorber tube. Renewable Energy77295.hn HT, Han H, Kim HT, Chun W. The performance simulation of alluum tubes with coaxial uid conduit. International Communicationsnd Mass Transfer 2007;34:5897.m JT, Ahn HT, Lee SJ. A three-dimensional performance analysis of all-uum tubes with coaxial uid conduit. International Communicationsnd Mass Transfer 2008;35:58996.urbo S. Vertical evacuated tubular-collectors utilizing solar radiationirection. Applied Energy 2004;78:37195.urbo S. Theoretical ow investigations of an all glass evacuated tubular

Solar Energy 2007;81:8228.ian R, Hou S, Zhang LN. Analysis on unsteady state efciency of glassd solar collector with an inserted heat pipe. Journal of Engineeringhysics 2008;2:32335.

S, Eleftheriou P, Lloyd S, Ward J. Design and performance char-s of a parabolic-trough solar collector system. Applied Energy34154.z-Garca A, Zarza E, Valenzuela L, Perez M. Parabolic-trough solar

and their applications. Renewable and Sustainable Energy Reviews1695721.Advances in solar thermal electricity technology. Solar Energy1931 [28 May 2008].orrison Graham L. Compact linear Fresnel reector solar thermal

nts. Solar Energy 2000;68:26383 [28 May 2008].ozl P, Pitz-Paal R, Meinecke W, Buck R. Costoptimized solar gas tur-es using volumetric air receiver technology. In: Proceedings of thee energy for the new millennium. 2000. p. 1717., Kolb GJ, Meinecke W. In: Becker M, Klimas PC, editors. Second

n central receiver technologies: a status report. Karlsruhe, Germany:993.. Nature 2001;414:33844, doi:10.1038/35104607 [15 November

ang L, Kang B, Wang P, Qiu Y. Review of recent progress in solid--sensitized solar cells. Solar Energy Materials & Solar Cells 2006;90:

, Hynes KM, Forbes I. Photovoltaic solar cells: an overview of state-of-ll development and environmental issues. Progress in Crystal Growthacterization of Materials 2005;51:142.cent advances of high-efciency single crystalline silicon solar cellssing technologies and substrate materials. Solar Energy Materials &s 2004;82:5364.

AM. Polycrystalline thin-lm solar cells a review. Solar Energy and Solar Cells 1998;55:7581.ntals of photovoltaic materials. National Solar Power Research Insti-8. (http://userwww.sfsu.edu/ciotola/solar/pv.pdf).. Amorphous silicon solar cells. WREC; 1996., Lamorte MF, McIver GW. IRE Transactions on Military Electronics0.I, Andreev VM, Kagan MB, Prostasov II, Trom VG. Soviet Physics-uctors 1971;40:2047.

Yamaguchi M, Takamoto T, Ikeda E, Agui T, Kurita H, et al. Charac-f GaAs-based concentrator cells. Solar Energy Materials & Solar Cells55965.S, Shay JL, Bachmann KJ, Buehler E. Applied Physics Letters229., Yamaguchi M, Coutts TJ, Meakin JD. Current topics in photovoltaics,don: Academic Press; 1989. p. 79234.Wanlass MW, Coutts TJ, Emery KA, Osterward CR.Proceeding 22ndpecialist conference. 1991. p. 365.Platz R, Keppner H. Thin-lm silicon solar cells: a review and selectedlar Energy Materials and Solar Cells 1995;38:50120.. Dye-sensitized solar cells. Journal of Photochemistry and Photobi-hotochemistry Reviews 2003;4:14553.din MdK, Baranoff E, Graetzel M. Dye-sensitized solar cells: a brief. Solar Energy 2011;85:11728.


[41] Chiba Y, Islam A, Watanabe Y, Komiya R, Koide N, Han L. Dye-sensitized solarcells with conversion efciency of 11.1%. Japanese Journal of Applied Physics2006;45(25):63840.

[42] Arif Hasan M, Sumathy K. Photovoltaic thermal module concepts and theirperformance analysis: a review. Renewable and Sustainable Energy Reviews2010;14:184559.

[43] Chow TT. A review on photovoltaic/thermal hybrid solar technology. AppliedEnergy 2010;87:36579.

[44] Erdil E, Ilkan M, Egelioglu F. An experimental study on energy generation witha photovoltaic (PV)solar thermal hybrid system. Energy 2008;33:12415.

[45] Chow TT, He W, Ji J. An experimental study of facade-integrated photovoltaic/water-heating system. Applied Thermal Engineering 2007;27:3745.

[46] Fraisse G, Menezo C, Johannes K. Energy performance of water hybrid PV/Tcollectors applied to combisystems of direct solar oor type. Solar Energy2007;81:142638.

[47] Assoa YB, Menezo C, Fraisse G, Yezou R, Brau J. Study of a new concept ofphotovoltaicthermal hybrid collector. Solar Energy 2007;81:113243.

[48] Kalogirou SA, Tripanagnostopoulos Y. Hybrid PV/T solar systems for domes-tic hot water and electricity production. Energy Conversion and Management2006;47:336882.

[49] Tiwari A, Dubey S, Sandhu GS, Sodha MS, Anwar SI. Exergy analysis of integratedphotovoltaic thermal solar water heater under constant ow rate and constantcollection temperature modes. Applied Energy 2009;86:25927.

[50] Touafek K

renewable energy

Documents

solar heating

solar energy conversion

solar thermal collectors13842

lms solar cells

liquid pvt collector

pvt air collector

solar greenhouse

silicon solar cells13883