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BITS PilaniPilani | Dubai | Goa | Hyderabad
CONCENTRATING SOLAR PHOTO-VOLTAIC
M. PadminiDr. Manoj S. Soni (Assistant Professor)Department of Mechanical EngineeringBITS – Pilani, Rajasthan
IV th International Conference on Advances in Energy Research10-12 December, 2013, IIT Bombay.
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
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Solar Photo-voltaic
• Photo-voltaic uses solar cells made up of semiconductors to generate
dc current from sunlight.
• Currently, polycrystalline and mono crystalline solar panels
generally available have efficiencies range from 12% to 18%.
• As solar panels are costly, such small efficiencies limit its use to only
specific applications.
• So to make this technique economical, there is a need to increase the
efficiency and to bring down the cost.
• One technique is to use concentrating photo-voltaic to increase the
intensity of light falling on solar cell
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
Concentrating photovoltaic
• Research into CPV started in the 1970s
• A large area of sunlight is focused onto the solar cell using optical
devices.
• Requires less photovoltaic material.
• As photovoltaic cell area required is less, high-efficient but
expensive multi-junction cells can be used economically.
• Optics is less expensive than cells
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
CPV Techniques
• Parabolic Concentrator
• Hyperboloid Concentrator
• Fresnel Lens Concentrator
• Compound Parabolic Concentrator (CPC)
• Dielectric Totally Internally Reflecting Concentrator (DTIRC)
• Quantum Dot Concentrator (QDC)
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
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Parabolic concentrator
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
Parabolic Concentrator
• Transforms an incoming plane wave traveling along the axis into a spherical
wave converging toward the focus.
• All incoming parallel light is reflected by the collector through a focal point
onto a second mirror.
• This second mirror is also a parabolic mirror with the same focal point.
• It reflects the light beams to the middle of the first parabolic mirror where it
hits the solar cell.
• The advantage of this configuration is that it does not require any optical
lenses.
• But losses will occur in both mirrors.
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
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Hyperboloid concentrator
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
8
Hyperboloid concentrator
• Consists of two hyperbolic sections, AB and A’B’.
• The diameters of the entrance and exit aperture are labeled as d1 and d2
respectively.
• If the inside wall of the hyperbolic profile is considered as a mirror, the sun
rays entering the concentrator from AA’ will be reflected and focused to the
exit aperture BB’.
• The advantage of this concentrator is that it is very compact, since only
truncated version of the concentrator needs to be used.
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
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Fresnel Lens
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
10
Fresnel Lens
• Comprises several sections with different angles, thus reducing weight and
thickness in comparison to a standard lens.
• Mostly made of poly(methyl methacrylate) (PMMA)
• Possible to achieve short focal length and large aperture while keeping the
lens light.
• They can be constructed
– In a shape of a circle to provide a point focus with concentration ratios of
around 500
– In cylindrical shape to provide line focus with lower concentration ratios.
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
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Compound Parabolic Concentrator
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
12
Compound Parabolic Concentrator
• When the rim of a parabola is tilted toward the sun, the rays are no
longer concentrated to a point, but are all reflected somewhere below
the focus.
• The rays on the right-hand side reflect below the focus and the rays
on the left-hand side reflect above the focus.
• So the half parabola tilted away from the sun is discarded, and
replaced with a similarly shaped parabola with its rim pointed toward
the sun
• A receiver is now placed in the region below the focus
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
13
Dielectric Totally Internally Reflecting Concentrator
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
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Dielectric Totally Internally Reflecting Concentrator
• DTIRC take advantage of the optical properties of a dielectric, namely its
refractive index, which leads to total internal reflection.
• Consists of three parts: a curved front surface, a totally internally reflecting
side profile and an exit aperture.
• The front aperture can be a hemisphere, but different designs such as
parabola and eclipse have been developed recently.
• The advantage of DTIRC over CPC is that it offers higher geometrical
concentration gain and smaller sizes.
• The disadvantage of a DTIRC is that it cannot efficiently transfer all of the
solar energy that it collects into a lower index media.
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
15
Quantum Dot Concentrator
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
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Quantum Dot Concentrator
• QDC is a planar device consisting of three parts;
– a transparent sheet of glass or plastic made doped with quantum dots
(QDs),
– reflective mirrors mounted on the three edges
– An exit where a PV cell is attached
• When the sun radiation hits the surface of a QDC, a part of the radiation
will be refracted by the fluorescent material and absorbed by the QDs.
• Photons are then reemitted in all direction and are guided to the PV cell via
total internal reflection.
• Works with diffuse light so does not need tracking.
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
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• Rod Lens
IV th International Conference on Advances in Energy Research
Recent Break-through
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
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Rod Lens
• Solar cell might be damaged if a small portion of the cell, on which unevenly
distributed light concentrates, gets hot.
• In a system with a Rod lens, it is possible to cause light to be shed on the entire
area of the solar cell.
• Can be used in both transmission type and reflection type concentrators
• In both types, light passes through rod lens before striking the solar cell to
enable uniform distribution of the rays.
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
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Solar Sphere
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
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• Solar Sphere
– Barcelona-based German-born architect André Broessel has con-
structed an enormous glass ball lens filled with water capable of
harnessing power from the sun and even the moon and converting
it into usable energy.
– He proposes that the spheres could be embedded in buildings al-
lowing for natural light to stream through while capturing valuable
energy
– The orb has been designed to be easily integrated into a building’s
design, replacing giant glass windows with a large sphere.
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
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APPLICATIONS TO INDIAN MARKET
• Moser Baer Clean Energy Limited (MBCEL) commissioned Asia's largest
solar farm in Banaskantha district of Gujarat.
• The 30 MW solar farm has been set up using 2,36,000 Thin Film modules
with an approximate investment of Rs 465 crore ( $95 million).
• Each module has surface area of 2600 x 2200 mm2 that is 5.72 m2.
• Total area of photovoltaic used was 17.3 Km2.
• We shall compare a new 30 MW plant with and without concentration
according to the current tariff rates.
• If we use 150W thin film polycrystalline cells, we can assert the cost to be
around Rs10000 per piece of area 1335 x 650 mm2.
• Fresnel lens costs around Rs100 per piece of area 350 x 350 mm2.
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
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Analysis Results
Without concentration With concentration
Expected output 30MW 30MW
PV sheet used150W Thin film Polycrystalline
cells150W Thin film Polycrystalline
cells
Area of photo-voltaic used 1,73,55,000 m2 3,54,183.67 m2
Total cost of PV cells used Rs 200 crore Rs14.16 crore
Area of Fresnel lens used - 1,73,55,000 m2
Cost of Fresnel lens - Rs 4.081 crore
Total cost of installation Rs 200 crore Rs 18.24 crore
IV th International Conference on Advances in Energy Research
BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956
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• The area of PV used will be reduced from 17.35Km2 to just 0.35Km2 which
would now cost Rs 14.16 crore.
• Adding to it the cost of Fresnel lens which would be Rs 4.081 crore, the
total material cost adds up to be around Rs 18.24 crore.
• CPV installation requires tracking and cooling mechanisms which would
account for an increase in cost of installation.
• But the amount would still be less than the initial cost and would also result
in a higher efficiency.
• So by installing Fresnel lens, we reduce the installation cost from an
exorbitant amount of Rs 200 crores to just above Rs 18 crores.
Conclusion
IV th International Conference on Advances in Energy Research
BITS PilaniPilani | Dubai | Goa | Hyderabad
THANK YOU