A Review on Photovoltaic Solar Energy Technology
and its Efficiency
Ahmed Hossam Eldin
Mostafa Refaey
Abdelrahman Farghly
a.hossamudn44@yahoo.com
moustafa.refaey@alexu.edu.eg
abdelrahman.farghly@alexu.edu.eg
Department of Electrical Engineering
University of Alexandria
Alexandria, Egypt
Abstract - Energy from sun can be considered the main
source of all types of energies. It can be used by various
techniques such as making full use of sunlight to directly generate
electricity or by using heat from the sun as a thermal energy.
Using Photovoltaic (PV) cells is common in solar energy field. The
major objective of this review study is to help anyone getting
through solar energy field by introducing developments up to
date in the field. One can be assisted and will save time of
building a literature review about PV by this review that is
considered part of a series compares the performance of PV
technologies. In this paper, a comparison survey is included
which investigates the three generations of PV cells with the latest
characteristics.
Index Terms - Photovoltaic technologies, Renewable Energy ,
Solar Energy, solar cells.
1. Introduction
Photovoltaic, also called solar cells, are electronic devices
that convert sunlight directly into electricity. Photovoltaic
power were first discovered by a French scientist Edmond
Becquerel in 1839. The first working solar cell was
successfully made by Charles fritts in 1882. It was made of
thin sheets of selenium and coated with gold. The use of solar
panels for generating electricity and heat seems relatively
like new development, it has actually been widely used to
generate power since early 1900‟s. In 1954 Bell laboratory
mass produced the first crystal silicon solar cell. The bell PV
converted 4% of the sun’s energy into electricity a rate that
was considered the cutting edge in energy technology. heir
scientists Daryl M. Chapin et al made a silicon-based solar
cell with an efficiency of about 6% reported in [1]. Scientists
continued to reinvent and enhanced on the design of the
original solar cell and were able to produce a solar cell that
was capable of putting 20% return electricity rate. In the late
1900‟s as awareness grew in the science community about
the effects of global warming and the need for renewable
energy sources, scientists continued to refine the silicon PV
and by early 2000 they were able to make a solar cell with
24% electricity return. In just seven years scientists were
again able to increase the electricity return of silicon solar
cell using space age materials. By 2007, modern silicon PV
Solar cells were operating with 28% electricity return. There
are a wide range of PV cell technologies on the market today
and more applications.
2. Photovoltaic Generation
PV cell technologies are usually classified into three
generations, depending on the basic material used [2].
1. Crystalline Silicon
2. Thin Film
3. Concentrated photovoltaic (CPV) and Organic
Material
2.1 First-Generation: Crystalline Silicon
Silicon is a semiconductor material illustrated in suitable
for PV applications, with energy band gap of 1.1 eV.
Crystalline silicon is the material commonly used in the PV
industry, wafer-based C-Si PV cells and modules dominate
the current market. Crystalline silicon cells are classified into
three types as :
• Mono-crystalline (Mono c-Si).
• Poly-crystalline(Poly c-Si),or multi-crystalline (mc-Si).
• Ribbon silicon
Commercial production of C-Si modules began in 1963 when
sharp Corporation of Japan started producing commercial PV
modules and installed a 242 W PV module on a light house,
the world’s largest commercial PV installation at that time [3].
Crystalline silicon technologies accounted for about 87% of
global PV sales in 2010 [4]. The efficiency of crystalline
silicon
modules
ranges
from
14%
to
19%.
While a mature technology continued cost reductions through
improvements in materials and manufacturing processes. if the
market continues to grow, enable a number of high-volume
manufacturers to emerge [5].
2.1.1 Mono-Crystalline silicon
Mono – crystalline silicon cells as shown in Fig. 1 have
the highest degree of efficiency of the three most common
technologies up to 20%.
Production: is a type of photovoltaic cell material
manufactured from a single crystal silicon structure
high purity silicon rods ( ingots ) are extracted from a cast
then cutted into thin slices ( wafers ), which are then
processed into PV cells. Expected lifespan of these cells is
typically 25 ‐ 30 years [6].
2.1.3 Ribbon Silicon
String Ribbon Si wafers are grown by a vertical sheet
growth technique that is currently in multi-megawatt
Production at Evergreen Solar [8]. This technique produces
low cost Si due to the high utilization of the Si feed stock. The
high quality of the processed String Ribbon wafers has been
previously demonstrated through high minority carrier
lifetimes following cell processing. Recent research on
processing String Ribbon cells has focused on industrial type
processing. The using of screen printing for metallization and
the relatively deep junctions necessary for firing the screen
printable inks. A few years ago, it has been recorded as high
with a percentage of 16.2% efficiency cell. However, recent
cells made with screen-printing are now approaching the 16%
level .
2.2 Second-Generation: Thin-Film
Fig. 1 Mono - Crystalline cell and module [7]
2.1.2 Poly-Crystalline silicon
The silicon molecular structure consists of several smaller
groups or grains of crystals, which introduce boundaries
between them as Shown in Fig. 2.
Production:The production of these cells is more
economically and more efficient compared to mono crystalline. Making the solar cell to have a lower efficiency.
unlike mono-crystalline silicon, the silicon is cast in blocks.
When it hardens, it results in crystal structures of different
sizes on whose border defects occur. These defects reduce
the degree of efficiency [6], Lab efficiency: 18% to 23% ,
and Production range: 14% to 17%.
Advantages:
•
Well established and tested technology
•
Stable efficiency
•
less expensive than single crystal silicon
•
square cells allow efficient packing density
Disadvantages:
•
Uses expensive material
•
Waste in slicing wafers
•
Slightly less efficient than single crystal
Thin - film solar cells are beginning to be deployed in
significant quantities. Thin - film solar cells could potentially
provide lower cost electricity than c-Si wafer based solar cells
[9]. Thin - film solar cells are comprised of successive thin
layers, just 1 to 4 µm thick, of solar cells deposited into a
large inexpensive substrate such as glass, polymer, or metal
and Cadmium is a by product of zinc. A potential problem is
that tellurium is produced in far lower quantities than cadmium
and availability in the long term may depend on whether the
copper industry can optimize extraction, refining and recycling
yields. Cadmium also has issues around its toxicity that may
limit its use. As a consequence, they require a less
semiconductor material to manufacture in order to absorb the
same amount of sunlight (up to 99% less material than
crystalline solar cells). In addition, thin films can be packaged
into flexible and light weight structures, which can be easily
integrated into building Components building integrated
Photovoltaic (BIPV). The three primary types of thin-film
solar cells that have been commercially developed are :
Amorphous silicon (A-Si and A-Si/µc-Si), Cadmium -Telluride (CdTe),
Copper-Indium-Selenide (CIS) and Copper-Indium-GalliumDiselenide (CIGS).
2.2.1 Amorphous silicon solar cells
Along with CdTe PV cells are the most developed and
widely known thin - film solar cells. Amorphous silicon can
be deposited on cheap and very large substrates ( up to 5.7 m²
of glass ) based on continuous deposition techniques, thus
considerably reducing manufacturing costs. A Companies are
also developing light, flexible A-Si modules perfectly suitable
for flat and curved surfaces, amorphous silicon module
efficiencies are in the range 4% to 8%. Very small cells at
laboratory level may reach efficiencies of 12.2% [10],[11].
see cell in Fig . 3.
Fig. 2 Poly - Crystalline cell and module [7]
The main disadvantage of amorphous silicon solar cells is
that they suffer from a significant reduction in power output
over time ( 15% to 35% ). As the sun degrades their
performance. Even thinner layers could increase the electric
field strength across the material and provide stability and less
reduction in power output, but this reduces light absorption
and hence cell efficiency. A notable variant of amorphous
silicon solar cells is the multi-junction thin-film silicon (a Si/µc Si) Which consists of A-Si cell with additional layers of
A -Si and micro crystalline silicon ( µc - Si) applied onto the
Substrate.
The advantage of the µc - Si layer is that it absorbs more
light from the red and near infrared part of the light
spectrum, thus increasing the efficiency by up to 10%. The
thickness of the µc - Si layer is in the order of 3 µm and
makes the cells thicker and more stable. The current deposition
techniques enable the production of multi-junction thin-films
up to 1.4 m².
Fig. 4 Illustrating a typical III-V triple junction solar [12]
Fig. 3 Amorphous solar cells
2.2.2 Cadmium Telluride and Concept of Multi-junction
The abbreviation CdTe stands for the combination of
tellurium and cadmium, which are combined to produce
cadmium telluride (CdTe) [6]. The material is cheaper than
silicon but also less efficient. As it contains the heavy metal
cadmium, the take back of the modules after reinstallations is
guaranteed. At present, a maximum degree of efficiency of
16 % is achieved.
2.2.2.1 Concept of Multi- Junction
PV devices can reach very high efficiencies because they
are often based on the multi - junction concept, which means
that more than one band gap is used. The maximum theoretical
efficiency of single-junction cells is described by the
Shockley-Queisser limit. A large fraction of the energy of
the energetic photons are lost as heat, while photons with
energies below the band gap are lost as they are not
absorbed., e.g, if we use a low band gap material, a large
fraction of the energy carried by the photons will be not used.
However, if we use more band gaps, the same amount of
photons can be used but less energy is wasted as heat. Thus,
large parts of the solar spectrum and largest part of the
energy in the solar spectrum can be utilized at the same time,
if more than one p-n junctions are used in Fig. 4
a typical III - V triple junction cell is illustrated. As substrate,
a germanium (Ge) wafer is used. From this wafer, the bottom
cell is created. Germanium has a band gap of0.67 eV. The
middle cell is based on GaAs and has a band gap of about
1.4 eV. The top cell is based on GaInP with a band gap in the
order of 1.86 eV. Let us take a closer look on how a multijunction solar cell works. Light will enter the device from the
top. As the spectral part with the most energetic photons (like
blue light) has the smallest penetration depth in materials, the
junction with the highest band gap always acts as the top cell.
On the other hand, as the near infrared light outside the visible
spectrum has the longest penetration depth, the bottom cell is
the lowest band gap.Fig. 5 shows the J-V curve of the three
single p-n junctions. We observe p-n junction one has the
highest open circuit voltage and the lowest short circuit current
density, which means that this p-n junction has the highest
band gap. In contrast, p-n junction three has a low open circuit
voltage and a high current density, consequently it has the
lowest band gap. p-n junction two has a band gap in between.
Hence, if we are designing a triple junction cell out of these
three junctions, junction one will act as the top cell, junction
two will act as the middle cell and junction three will act
as the bottom cell.
Fig. 7 Multi-junction circuit [12]
Fig. 5 The J -V curves of the three junctions [12]
For understanding how the J - V curve of the triple
junction looks like, we take a look at the equivalent circuit.
Every p-n junction in the multi-junction cell can be
represented by the circuit of a single – junction cell
Fig. 6. As the three junctions are stacked onto each other,
they are connected to each other in series, as illustrated in
Fig. 7. In a series connection, the voltages of the individual
cell add up in the triple junction cell. Further,
the current
density in a series connection is equal over the entire solar
cell. hence the current density is determined by the p-n
junction generating the lowest current. The resulting J -V
curve is also in Fig. 5. We see that the voltages add up and
the current is determined by the cell delivering the lowest
current [12].
The development of efficiency in multi-junction as follow
From with concentration method will discuss in the Table. 1.
Table. 1 Efficiency recent for research of PV and CPV [13]
Type
Single-Junction ( non concentrator )
Single-Junction ( concentrator )
Double-Junction ( non concentrator )
Double-Junction ( concentrator )
Triple-Junction ( non concentrator )
Triple-Junction ( concentrator )
Four-junction ( non concentrator )
Effeciency
25%
27.6%
31.1%
32.6%
37.7%
44%
37.8%
2.2.3 Copper-Indium-Selenide (CIS) and Copper-Indium
Gallium-Diselenide (CIGS)
(CIGS) PV cells offer the highest efficiencies of all
thin-film PV technologies. CIS solar cell production has been
successfully commercialized by many firms as shown in
Fig. 8. Current module efficiencies are in the range of 7% to
16%, but efficiencies of up to 20.3% have been achieved in the
laboratory, close to that of C-Si cells [14]. The race is now on
to Increase the efficiency of commercial modules. CIGS
producer Solar Frontier has reached an annual Production
capacity of 1 GW (Bank Sarasin, 2010). on the one hand, the
CIGS module has the advantage of a low static load thanks to
its light cells, while it also has the ability to absorb direct and
indirect sunlight and is therefore suitable for use on flat roofs
and in winter.
Fig. 6 Single junction circuit [12]
Fig. 8 Copper-Indium-Selenide (CIS) cells
2.3 Third-Generation PV Technologies
Third - generation PV technologies are at the precommercial stage and vary from technologies under
Demonstration ( Multi - junction concentrating PV ) to novel
concepts still in need of (quantum-structured PV cells). Some
third - generation PV technologies are beginning to be
commercialized, but it remains to be seen how successful
they will be in taking market share from existing technologies.
There are four types of third-generation PV technologies:
Concentrating PV (CPV), Cooling of concentrating PV
system, Organic solar cells and Dye-sensitized solar cells
(DSSC).Responsible for the charge separation (photocurrent)
2.3.1 Concentrating photovoltaic technology
The concentrator is an important component for
concentrating PV systems. It is classified according to optical
principle, concentrator types, and geometric concentration
ratio. The line focus solar concentrator includes the lens,
parabolic trough, and line focusing parabolic collector. The
point focusing concentrator is called the axial concentrator.
The concentrator lens or reflectors of this type of concentrator
are on the same optical axis of the solar cell [15]. According
to the geometric concentration ratio, the concentrator can be
divided into a low-concentration system and a high
concentration system with a solar tracking. Although the
concentration ratio of the low-concentration system is not
high, the scattered radiation can be used without a solar
tracking and be applied in the area with inadequate direct
radiation. Generally, if the concentration ratio is more than 10,
the system can only use direct sunlight. As a result, the
tracking system must be adopted. Since the mid - 1970s,
with a concentration ratio of 50 and efficiency of 12.7%, the
first concentrating PV system was developed in Sandia
National Laboratories in US. This technology has rapidly
developed. In its earlier stage, the Fresnel lens was superior
in property to other light concentrating devices.
The passive cooling was also feasible with the highconcentration ratio, and the application of the diamond plate
and copper heat sink promoted the development of the
technology. The schematic diagram of the PV concentrator
Fresnel lens is shown in Fig. 9. The solar PV power generation
has benefited from the improvement of the Fresnel lens. For
instance, the 20 kW point focusing Fresnel lens array was
developed by A monix and Sun Power after 15 years of
continuous research designed the modularized and micro
faceted Fresnel lens with a moderate concentration ratio,
bringing about efficient superposition and finally uniform
distribution of incident solar flux [16],[17]. They also
formulated a mathematical model to solve the distribution of
the energy flux on PV panel and the collecting efficiency. The
calculation indicates that the non - uniformity of energy
distribution remains within 20%. Under the condition of the
lower-middle concentration ratios (50 times), the radiation
transmittance is more than 70% designed the full glass high
concentration ratio PV modular with second concentration lens
of small aperture between the Fresnel lens and cells [18],
which further improve the light concentration. The
concentrating ratio of the concentrator system reaches 1000,
and the size of PV is only 1.2 mm. It is convenient to scale up
the module and improve its weathering resistance. [19]
designed a line focused PV system with Fresnel lens. It was
found that heat conduction between solar cells and heat
absorber is crucial to the energy efficiency of the whole
system.Recently, [20]conducted extensive indoor experimental
investigation on the heat loss from a point focus Fresnel lens
PV concentrator with a concentration ratio of 100 times
under a range of simulated solar radiation intensities between
200 and 1000 W/m at different ambient air temperatures,
and natural and forced convection. It was found that the solar
cell temperature increased proportionally with the increase
in simulated solar radiation for all experimental tests,
indicating that conductive and convective heat transfer were
significantly larger than the long wave radiative heat transfer
within and from the system.
Fig. 9 Schematic of PV concentrator Fresnel lens
The reflecting concentrator can overcome this weakness. The
point focused rotating parabolic concentrators and the line
focused trough-type concentrators PV systems are mostly
employed in the reflective PV concentrator. A representative
10 m trough concentrator PV with geometric concentration
ratio of 30.8 is shown in Fig. 10(a) [21].The trough-type PV
system caused the solar cell to be between the sun and the
reflecting surface. The solar cell is always below the reflective
parabolic focal line where the rays are inevitably sheltered,
thus leading to optical non - uniform flux distribution. In
recent years, the butterfly – shaped PV concentrator has been
developed. A row of plane mirrors is installed at its bottom.
A solar cell module is fixed on its top, reducing the shelter of
sunlight by the PV devices to a certain extent [22] developed
a butterfly - shaped PV concentrator, as shown by the Fig.
10(b). The sunlight reflected through the mirror plane
uniformly
reaches the
solar cell array of
the
corresponding side, with its concentrations varying between
2 and 12 times. A multidisc parabolic concentrator PV with
adual-axis tracking system was developed by NREL of US.
This disc type concentrator system includes 16 reflecting
surfaces, with each surface containing 76 reflecting blocks.
The mirror area of the system covers 113 m with a highly
precise tracking system and a concentration ratio of 250 [23].
The well - known Spanish solar energy research institution
PSA developed a multidisc PV concentrator demonstration
system with a concentration ratio of 2000. It includes the
heliostat, optical grating, multidisc concentrator, and PV board
and can simultaneously test the PV response to the direct
solar radiation and thermal flux distribution [24]. In terms of
the low concentration PV system, [25] integrated the monocrystalline silicon solar cell into the V-type reflection trough
made of aluminum foil.
2.3.2 Cooling of Concentrating PV System
For different types of concentration PV at a fixed
temperature, the general tendency of the change in the solar
cell efficiency corresponds to the change in the concentration
ratio. The cell efficiency increases with the increase in the
concentration ratio at the low concentration ratio and
decreases with the increase in the concentration ratio at the
high-concentration ratio. Under the condition of the given
output power, the tandem-type cell may increase the voltage
output and reduce the ohmic loss. However, the non uniformity of light intensity distribution and the poor heat
dissipation leads to overheat of the cell panel, affecting the
current output of the whole cell array. This is called “the
current matching problem.” The effective PV cell cooling or
the appropriate design of the concentrator may lessen the
consumption of the parasitic power [27].
J.Wennerberg, J.Kessler at el [28] demonstrated that the
distribution of light intensity produced by the parabolic trough
concentrator is similar to a Gaussian curve. Compared to
uniform illumination, both the open - circuit voltage and
efficiency of the concentrator PV cell would decrease. The
decrease could be aggravated when the peak intensity of
light distribution is increased. This decrease may lead to a
serious non-uniform flux distribution. Currently, tandem type
module was adopted by most polycrystalline silicon solar cells
and the current output of each cell module is equal in this case.
For such type of module, the low light intensity in some areas
(corresponding to the smaller light current) greatly limits the
general current output of the whole PV system. Therefore, in
case one or more cells are shaded, module performance will be
limited by the output of these cells [29].
2.3.3 Organic solar cells
(a)
(b)
Fig. 10 Representative CPV system [26]
a) Trough CPV system
b) Butterfly-shaped
Organic solar cells are composed of organic or polymer
materials as shown in Fig. 11. They are inexpensive, but not
very efficient. Organic PV module efficiencies are now in the
range 4% to 5% for commercial systems and 6% to 8% in the
laboratory [30]. In addition to the low efficiency, Suppliers of
organic solar cells are moving towards full commercialization
and have announced plans to increase production to more than
1 GW [31].Organic cell production uses high speed and low
temperature roll-to-roll manufacturing processes and standard
printing technologies. As a result, organic solar cells may be
able to compete with other PV technologies in some
applications, because manufacturing costs are continuing to
decline and are expected to reach $ 0.50/W by 2020
[32].Organic cells can be applied to plastic sheets in a manner
similar to the printing and coating industries, meaning that
organic solar cells are light weight and flexible as shown in
Fig. 12, making them ideal for mobile applications and for
fitting to a variety of uneven surfaces. This makes them
particularly useful for portable applications, Potential uses
include battery chargers for mobile phones, laptops, radios,
Flash lights, toys and almost any hand held device that uses a
battery.They can also be rolled up or folded for storage when
not In use. These properties will make organic PV modules
attractive for building-integrated applications as it will expand
the range of shapes and forms where PV systems can be
applied. Another advantage is that the technology uses
abundant, non-toxic materials and is based on a very scalable
production process with high productivity. Novel and
emerging solar cell concepts in addition to the above
mentioned third-generation technologies that relay on using
quantum dots/wires, quantum wells, or super lattice
technologies [33]. These technologies are likely to be used in
concentrating PV technologies where they could achieve very
high efficiencies by overcoming the thermodynamic
limitations of conventional (crystalline) cells. The novel
concepts, often incorporating enabling technologies such as
nanotechnology, which aim to modify the active layer to
better match the solar spectrum [34].
Fig. 11 Organic PV construction [35]
Fig. 12 Organic PV sample [35]
2.3.4 Dye-sensitized solar cells (DSSC)
Solar cells use photo-electrochemical solar cells, which
are based on semiconductor structures formed between a
photo - sensitized anode and an electrolyte. In a typical
DSSC, the semiconductor nano crystals serve as antenna
that harvest the sunlight (photons). the dye molecule is
responsible for the charge separation (photocurrent). It is
unique in that it mimics natural photosynthesis [36]. These
cells are attractive because they use low cost materials and
are simple to manufacture, e.g, titanium dioxide covered by a
light absorbing pigment. However, their performance can
degrade over time with exposure to UV light and the use of a
liquid electrolyte can be problematic when there is a risk of
freezing.
3. Black silicon solar Cell
New nanostructured silicon solar cells coated with a
passivating film as shown in Fig. 13, The nanostructuring of
silicon surfaces is a promising approach to eliminate frontsurface reflection in photovoltaic devices without the need for
a conventional antireflection coating. This might lead to both
an increase in efficiency and a reduction in the manufacturing
costs of solar cells. However, all previous attempts to integrate
black silicon into solar cells have resulted in cell efficiencies
well below 20% due to the increased charge carrier
recombination at the nanostructured surface. Here, we show
that a conformal alumina film can solve the issue of surface
recombination in black silicon solar cells by providing
excellent chemical and electrical passivation. We demonstrate
that efficiencies above 22% can be reached, even in thick
interdigitated back-contacted cells, where carrier transport is
very sensitive to front surface passivation. This means that the
surface recombination issue has truly been solved and black
silicon solar cells have real potential for industrial production.
Furthermore, we show that the use of black silicon can result
in a 3% increase in daily energy production when compared
with a reference cell with the same efficiency, due to its better
angular acceptance [37].
Fig. 13 Black Silicon Solar Cell
4. Conclusions
First-generation solar cells dominate the market with
their low costs and the best commercially available efficiency.
They are a relatively mature PV technology, with a wide range
of well-established manufacturers. Although very significant
cost reductions occurred in recent years, the costs of the basic
materials are relatively high. It is not clear whether further
cost reductions will be sufficient to achieve full economic
competitiveness in the wholesale power generation market in
areas with modest solar resources.
Second-generation Thin-film PV technologies are attractive
because of their low material and manufacturing costs, but this
has to be balanced by lower efficiencies than those obtained
from first-generation technologies. Thin-film technologies are
less mature than first generation PV and still have a modest
market share, except for utility-scale systems. They are
struggling to compete with very low c-Si module prices and
also face issues of durability, materials availability and
materials toxicity (in the case of Cadmium).
Third-generation technologies are yet to be commercialized
at any scale. Concentrating PV has the potential to have the
highest efficiency of any PV module, Other organic or hybrid
organic/conventional (DSSC) PV They offer low efficiency,
but also low cost and weight, and free-form shaping.
Therefore, they could fill niche markets (e.g. mobile
applications) where these features are required.
5. References
[1] Chapin, D. M.; Fuller, C. S.; Pearson, G. L. Affiliation. Appled . Phys,
vol. 25, 1954, pp. 676.
[2] Irena working paper, "Renewable Energy technologies: cost analysis
series", IRENA ,vol. 1, 2012, issue 4/5.
[3] Green, M. A, " Clean Energy from Photovoltaics ", World Scientific
Publishing Co., Hackensack, NJ, 2001.
[4] Schott solar, "Solar Crystalline Silicon Technology", internet:http:
//www.us.schott.com/photovoltaic/english/About_pv/technologies/crystalline.
[5] B.Mills, Internet :http://commons.wikimedia.org/wiki/File: Silicon-unitcell-3D-balls.png, September 2007.
[6] Dena German Energy Agency, "Information about German renewable
energy, industries, companies and product(Federal Ministry of Economics
and Technology)", pp. 41, 2013-2014, ISIN: B002MNZE4U.
[7] Energy Market Authority, " Handbook for solar photovoltaic(PV)
systems", pp. 8.
[8] E. Sachs, J. Cryst, "String Ribbon Growth Technique",(Evergreen Solar,
Sovello) Growth, vol. 82, 1987, pp. 117.
[9] K. L. Chopra, P . D. Paulson, and V. Dutta," Thin - film solar cell
overview", Prog. Photovoltaic: Res.,vol. 12, , 2004, pp. 69-92.
[10] Mehta, S. ,"PV Technology, Production and Cost", Outlook: 2010-2015,
Greentech Media Research, October, 2010, Boston, MA.
[11] A. A. Hossam El –din, C. F. Gabra and Ahmed H. H. Ali ," A
Comparative Analysis Between the Performances of Monocrystalline,
Polycrystalline and Amorphous Thin Film in Different Temperatures at
Different Locations in Egypt", Solar Energy Conference, March 2014.
[12] Arno Smets, Klaus Jäger,Olindo Isabella, René van Swaaij, Miro Zeman,
"Solar Energy, Fundamentals, Technolgy, and systems (UIT Cambridge)",
2014, pp. 109, ISBN: 9781906860325.
[13] NREL," Best research-cell efficiency", internet: http://www.nrel.gov/.
[14] Green, M.A. et al, " Solar Cell E£ciency Tables progress in
Photovoltaics: Research and Applications", Vol. 19, 2011, pps 84-92.
[15] G. Zubi, J. L. Bernal-Agust´ın, and G. V. Fracastoro, “High
concentration photovoltaic systems applying III-V cells,” Renewable &
Sustainable Energy Reviews, vol. 13, no. 9, 2009, pp. 2645–2652.
[16] K.Ryu,J.G.Rhee,K.M.Park,andJ.Kim,“Conceptand design of modular
Fresnel lenses for concentration solar PV system,”Solar Energy, vol. 80, no.
12, 2006, pp. 1580–1587.
[17] V. Garboushian, D. Roubideaux, and S. W. Yoon, “Integrated highconcentration PV alternative for large-scale solar electric power,”Solar
Energy Materials & Solar Cells, vol. 47, no. 1–4, , 1997, pp. 315–323.
[18] V. M. Andreev, V. A. Grilikhes, V. P. Khvostikov et al., “Concentrator
PV modules and solar cells for TPV systems,” Solar Energy Materials & Solar
Cells, vol. 84, no. 1–4, , 2004, pp. 3–17.
[19] J. I. Rosell, X. Vallverd´ u, M. A. Lech´ on, and M. Ib´ a˜ nez, “Design
and simulation of a low concentrating photovoltaic/thermal system,”Energy
Conversion & Management, vol. 46, no. 18-19, 2005, pp. 3034–3046.
[20] Y.P.Wu,P.Eames,T.Mallick,andM.Sabry,“Experimental characterisation
of a Fresnel lens photovoltaic concentrating system,”Solar Energy, vol. 86,
no. 1 , 2012, pp. 430–440.
[21] M. Li, X. Ji, G. L. Li, Z. M. Yang, S. X. Wei, and L. L. Wang,
“Performance investigation and optimization of the Trough Concentrating
Photovoltaic/Thermal system,”Solar Energy, vol. 85, no. 5 , 2011, pp. 1028–
1034.
[22] Z.L.Xu,J.D.Liu,P.F.Feng,D.P.Hou,J.Y.Zhang,andY.M. Zhang, “Research
on a butterfly concentrator for photovoltaic generation,”Acta Energiae Solaris
Sinica,vol.28, no.2 , 2007, pp. 174–177.
[23] L. Zhu, R. F. Boehm, Y. P. Wang, C. Halford, and Y. Sun, “Water
immersion cooling of PV cells in a high concentration system,”Solar Energy
Materials & Solar Cells, vol. 95, no. 5 , 2011, pp. 538–545.
[24] J. Fern´ andez-Reche, I. Ca˜ nadas, M. S´ anchez et al., “PSA Solar
furnace: a facility for testing PV cells under concentrated solar
radiation,”Solar Energy Materials & Solar Cells, vol. 90, no. 15, 2006, pp.
2480–2488.
[25] C. S. Solanki, C. S. Sangani, D. Gunashekar, and G. Antony,“Enhanced
heat dissipation of V-trough PV modules for better performance,”Solar
Energy Materials & Solar Cells, vol. 92, no.12, 2008, pp. 1634–1638.
[26] Longzhou Zhang, Dengwei Jing, Liang Zhao at el." Review Article
Concentrating PV/T Hybrid System for Simultaneous Electricity and Usable
Heat Generation', photoenengy, vol . 2012, pps. 8.
[27] T. T. Chow, “ A Review on photovoltaic / thermal hybrid solar
technology,”Applied Energy, vol. 87, no. 2, 2010, pp. 365–379.
[28] J. Wennerberg, J. Kessler, J. Hedstr¨ om, L. Stolt, B. Karlsson, and M. R¨
onnelid, “Thin film PV modules for lowconcentrating systems,”Solar Energy,
vol. 69, supplement 6, 2001, pp. 243–255.
[29] M. Hein, F. Dimroth, G. Siefer, and A. W. Bett, “Characterisation of a
300×photovoltaic concentrator system with one-axis tracking,”Solar Energy
Materials & Solar Cells, vol. 75, no. 1-2, 2003, pp. 277–283.
[30] Orga PV net,"Technology Roadmap Towards Stable & Low-cost
Organic Based Solar Cells", Orga PV net, 2009.
[31] European Photovoltaic Industry Association (EPIA),Solar Generation 6:
Solar Photovoltaic Energy Empowering the World, 2011, EPIA, Brussels.
[32] Nozik, A. et al, Multiple Exciton Generation in Colloidal Quantum Dots,
Singlet Fission in Molecules, Quantum Dot Arrays, Quantum Dot Solar Cells,
and Effects of Solar Concentration, Presentation to the symposium “ThirdGeneration and Emerging Solar-Cell Technologies”, April 26 - 29, 2011.
[33] Leung, Siu-fung et al, “Third-Generation and Emerging Solar-Cell
Technologies”, Engineered Optical Absorption of Nano/Micro-pillar Arrays
for Efficient Photovoltaics, presentation to the symposium , April 26 - 29,
2011.
[34] BASF company, " layer of organic materal " , internet: http://
www.solarserver.com/solarmagazin/solar-report_0807_e.html.
[35] EcoFriend,"the last update in renewable energy and organic PV",
internet: http://www.ecofriend.com/category/latest.
[36] Grätzel, M. and O’Regan, B, “A Low-Cost, High-E£ciency Solar Cell
Based on Dyesensitized Colloidal TiO2 Films”, Nature, Vol. 353, pp 737740, 1991.
[37] Hele Savin, Päivikki Repo at el," Black silicon solar cells with
interdigitated back-contacts", Nature nano technology, vol. 10, 2015, pp.
624-628.