Title of Invention

AN IMPROVED SOLAR PHOTOVOLTAIC MODULE

Abstract An improved solar photovoltaic module comprising a heat dissipator body made of a high thermal conductor material and having a flat base and a plurality of contiguous V-shaped troughs integrally formed with the flat base along the length thereof, each of the V-shaped troughs comprising a flat bottom portion and a pair of sidewalls inclined to the flat bottom portion at an angle of 15 to 30°, the solar photovoltaic module further comprising a plurality of laminated photovoltaic cell strips, each located in each of the V-shaped troughs against the flat bottom portion thereof and* comprising a plurality of photovoltaic cells connected to one another in series by bus bars and sandwiched between a bottom protective layer and a top protective layer, an electric insulator layer affixed to the bottom protective layer and a transparent cover affixed to the top protective layer, the sidewalls and bottom portion of the V-shaped troughs forming heat dissipating surfaces and the sidewalls of the V-shaped troughs also forming light reflective surfaces.
Full Text FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION (See section 10 and rule 13)
TITLE OF THE INVENTION
An improved solar photovoltaic module INVENTORS
Names : Prof Solanki Chetan Singh and Sangani Chintan Sureshkumar
Nationality : both Indian Nationals
Address : both of Indian Institute of Technology, Bombay,
Department of Energy Systems Engineering, Powai, Mumbai 400076, Maharashtra, India
APPLICANTS
Name : Indian Institute of Technology, Bombay
Nationality : an autonomous research and educational
institution established in India by a special Act of the Parliament of the Republic of India under the Institutes of Technology Act 1961
Address : Powai, Mumbai 400076, Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed :

FIELD OF INVENTION
This invention relates to an improved solar photovoltaic module.
BACKGROUND OF INVENTION
Electric power is becoming scarce day by day because of the ever increasing demand and limited resources for generation. Generation of electric power by conventional power plants is not only expensive but also highly polluting. It also gradually depletes the available natural resources. Against this background, generation of clean electric power with little or no emissions and environment friendly technology assumes great importance. Photovoltaic cell technology for generation of electric power has several advantages. It makes use of sunlight which is easily available in abundance in many parts of the world almost throughout the year especially countries like India. It does not have any moving parts and is non-polluting. Therefore, efforts are on to develop photovoltaic cell technology for generation of electric power as an alternative in commercial applications like street lighting, rural household electrification or irrigational water pumps. A solar photovoltaic system comprises one or more photovoltaic modules each having rows of photovoltaic cells connected to one another in series by bus bars and sandwiched between a bottom protective layer and a top protective layer. An electric insulator layer is fixed to the bottom protective layer and a transparent cover is fixed to the top protective layer. An alluminium reinforcing frame is fitted at the bottom of the module and extends upto the electric insulator layer. The photovoltaic cells are usually made of silicon which is expensive and is also in short supply. In order to reduce the cell area and increase the cell output, the module is provided with a pair of light reflectors each located at each end of the module to form a V-trough. The light reflectors are mirrors, anodised aluminium sheets or ceramic coated aluminium sheets. The light reflectors are difficult to handle and manoeuvre because of their large and unwieldy size.
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They also increase the size and cost of the modules. Due to the light reflectors, the light or flux intensity falling on the photovoltaic module is increased. The increase in the light flux falling on the module will in turn increase the temperature in the module. Unless the module is provided with additional cooling means, the temperature increase will lead to voltage drops thereby reducing the voltage output of the module. The additional cooling means will increase the cost of the module.
OBJECTS OF INVENTION
An object of the invention is to provide an improved solar photovoltaic module, which increases the light or flux intensity falling on the photovoltaic cells and improves heat dissipation without additional cooling means and also improves open circuit voltage and power output.
Another object of the invention is to provide a solar photovoltaic module, which reduces the cell area and cost and increases the cell life.
Another object of the invention is to provide a solar photovoltaic module, which is compact and mechanically strong and sturdy.
DETAILED DESCRIPTION OF INVENTION
According to the invention there is provided an improved solar photovoltaic module comprising a heat dissipator body made of a high thermal conductor material and having a flat base and a plurality of contiguous V-shaped troughs integrally formed with the flat base along the length thereof, each of the V-shaped troughs comprising a flat bottom portion and a pair of sidewalls inclined to the flat bottom portion at an angle of
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15 to 30°, the solar photovoltaic module further comprising a plurality of laminated photovoltaic cell strips, each located in of each of the V-shaped troughs against the flat bottom portion thereof and comprising a plurality of photovoltaic cells connected to one another in series by bus bars and sandwiched between a bottom protective layer and a top protective layer, an electric insulator layer affixed to the bottom protective layer and a transparent cover affixed to the top protective layer, the sidewalls and bottom portion of the V-shaped troughs forming heat dissipating surfaces and the sidewalls of the V-shaped troughs also forming light reflective surfaces.
The following is a detailed description of the invention with reference to the accompanying drawings, in which:
Fig 1 is schematic isometric view of the improved solar photovoltaic module according to an exemplary embodiment of the invention;
Fig 2 is plan view of the module of Fig 1; and
Fig 3 is schematic isometric view of the heat dissipator body of the module of Fig 1.
The solar photovoltaic module 1 as illustrated in Figs 1 to 3 of the accompanying drawings comprises a heat dissipater body 2 made of a high thermal conductor material and having a flat base 3 and a plurality of contiguous V-shaped troughs 4 integrally formed with the flat base along the length thereof (Fig 3). Each of the V-shaped troughs comprises a flat bottom portion 4a and a pair of sidewalls 4b inclined to the flat bottom portion. Each of the troughs further comprises a plurality of laminated photovoltaic cell strips 5 each located in each of the V-shaped troughs against the flat bottom portion thereof and comprising a plurality of photovoltaic cells 6 connected to one another in
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series by bus bars (not shown) and sandwiched between a bottom protective layer 7 and a top protective layer 8. 9 is an electric insulator layer fixed to the bottom protective layer. 10 is a transparent cover fixed to the top protective layer. The heat dissipator body is preferably made of aluminium. The photovoltaic cells comprise mono, multi or amorphous silicon. The electric insulator layer is preferably made of polyvinyl fluoride. The transparent cover is preferably made of glass. The bottom and top protective layers are preferably made of ethylvinyl acetate. The side walls of the V-shaped troughs are inclined at an angle of 15 to 30°, preferably 20°. The side walls of the V-shaped troughs form light reflective surfaces so as to concentrate and increase the light or flux intensity falling on the photovoltaic cells. Due to the large number of V-shaped troughs light intensity falling on the cells is increased considerably. The heat generation in the module is also correspondingly increased. The sidewalls and bottom portion of the V-shaped troughs form increased surface area for effective dissipation of the heat by conduction and radiation. A convective current is also formed in the hollow space between the sidewalls of the V-shaped troughs so as to further improve the heat dissipation. Due to the integral construction of the heat dissipator body with high thermal conductor material, heat dissipation of the module is further improved. Preferably the total area of the sidewalls and bottom portion of each of the V-shaped troughs is four times the cell area of each of the laminated photovoltaic cell strips so as to further improve light concentration and heat dissipation. Due to the increase in the light intensity on the cells, the cell area can be reduced for a given cell output. As the cell area is reduced without reducing cell output there is considerable cost benefit in terms of the material of the silicon cells. The heat dissipator body acts as a heat sink and improves dissipation of the heat being generated in the module due to increased light falling on the cells and does away with additional cooling means for the module. Therefore, voltage losses due to
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temperature rise in the module is reduced and open circuit voltage (Voc) and power output are improved. As the light reflectors are inclined they can collect sunlight at least 8 hrs of sunshine without the necessity of diurnal tracking arrangement. The invention thus does away with the diurnal tracking arrangement also. Due to the integrated construction of the photovoltaic module of the invention with the heat dissipater body as a contiguous structure and location of the cell strips within the troughs, the photovoltaic module is mechanically strong and sturdy and also compact. It also does away with the separate end reflectors and instead the light reflective surfaces are integrally formed into the module.
Comparative studies were carried out with an improved solar photovoltaic module of 40 watts rating as per the invention and a conventional solar photovoltaic module of 40 watts rating comprising a pair of mirrors located at each end thereof. The cells were made of monosilicon. The maximum temperature rise was measured at 12 noon. The open circuit voltage (Voc) and power output were also measured at 12 noon. The results were as shown in the Table
Table

Number of cells Area ofeach cell(cm2) Total area of the cells(cm2) Maximumtemperaturerise (°C) Voc (Volts) Power output(W)
Conventionalphotovoltaicmodule 36 78.125 2812.5 90 18.0 31
Improvedphotovoltaicmodule 36 50 1800 60 19.5 33.5
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The Table clearly shows that there was 64% reduction in the cell area in the case of the improved photovoltaic module of the invention. The Table also shows that the rise in temperature in the case of the photovoltaic module of the invention was 60°C maximum, whereas in the case of the conventional module the temperature rise was 90°C. The Table also shows that open circuit voltage and power output increased in the case of the photovoltaic module of the invention by 9% which is quite significant in a large scale photovoltaic module. It is quite evident that the improved light concentration and heat dissipation not only increase the open circuit voltage and power output but also help to reduce the cell area. Because of the reduced temperature rise in the photovoltaic module, cell life is also improved and the photovoltaic module is very economical.
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We claim:
1. An improved solar photovoltaic module comprising a heat dissipator body made of a high thermal conductor material and having a flat base and a plurality of contiguous V-shaped troughs integrally formed with the flat base along the length thereof, each of the V-shaped troughs comprising a flat bottom portion and a pair of sidewalls inclined to the flat bottom portion at an angle of 15 to 30°, the solar photovoltaic module further comprising a plurality of laminated photovoltaic cell strips, each located in each of the V-shaped troughs against the flat bottom portion thereof and* comprising a plurality of photovoltaic cells connected to one another in series by bus bars and sandwiched between a bottom protective layer and a top protective layer, an electric insulator layer affixed to the bottom protective layer and a transparent cover affixed to the top protective layer, the sidewalls and bottom portion of the V-shaped troughs forming heat dissipating surfaces and the sidewalls of the V-shaped troughs also forming light reflective surfaces.
2. A solar photovoltaic module as claimed in claim 1, wherein the total area of the sidewalls and bottom portion of each of the V-shaped troughs is four times the cell area of each of the laminated photovoltaic cell strips.
3. A solar photovoltaic module as claimed in claim 1 or 2, wherein the heat dissipator body is made of aluminium.
4 . A solar photovoltaic module as claimed in any one of claims 1 to 3, wherein each of the photovoltaic cells comprises mono, multi or amorphous silicon.
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5. A solar photovoltaic module as claimed in any one of claims 1 to 4, wherein the electric insulator layer comprises polyvinyl fluoride.
6. A solar photovoltaic module as claimed in any one of claims 1 to 5, wherein the transparent cover is made of glass.
7 . A solar photovoltaic module as claimed in any one of claims 1 to 6, wherein the bottom and top protective layers each comprises ethylvinyl acetate.
8. A solar photovoltaic module as claimed in claims 1 to 7, wherein the sidewalls of the troughs are inclined to the flat bottom portion thereof at an angle of 20°.

(Prita Madan)
of Khaitan &Co
Agent for the Applicants
Dated this 1st day of June 2007
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Documents:

1051-mum-2007-abstract(4-6-2007).pdf

1051-MUM-2007-ABSTRACT(GRANTED)-(12-1-2012).pdf

1051-MUM-2007-CANCELLED PAGES(25-11-2011).pdf

1051-MUM-2007-CLAIMS(AMENDED)-(25-11-2011).pdf

1051-MUM-2007-CLAIMS(GRANTED)-(12-1-2012).pdf

1051-mum-2007-claims.doc

1051-mum-2007-claims.pdf

1051-MUM-2007-CORRESPONDENCE(11-1-2010).pdf

1051-MUM-2007-CORRESPONDENCE(23-1-2009).pdf

1051-mum-2007-correspondence(23-10-2007).pdf

1051-mum-2007-correspondence(4-6-2007).pdf

1051-MUM-2007-CORRESPONDENCE(IPO)-(12-1-2012).pdf

1051-mum-2007-descripiton (complete).pdf

1051-MUM-2007-DESCRIPTION(GRANTED)-(12-1-2012).pdf

1051-mum-2007-drawing(4-6-2007).pdf

1051-MUM-2007-DRAWING(GRANTED)-(12-1-2012).pdf

1051-mum-2007-form 1(10-10-2007).pdf

1051-MUM-2007-FORM 1(25-11-2011).pdf

1051-MUM-2007-FORM 1(4-6-2007).pdf

1051-MUM-2007-FORM 13(25-11-2011).pdf

1051-mum-2007-form 18(23-10-2007).pdf

1051-MUM-2007-FORM 2(GRANTED)-(12-1-2012).pdf

1051-MUM-2007-FORM 2(TITLE PAGE)-(25-11-2011).pdf

1051-mum-2007-form 2(title page)-(4-6-2007).pdf

1051-MUM-2007-FORM 2(TITLE PAGE)-(GRANTED)-(12-1-2012).pdf

1051-mum-2007-form 26(10-10-2007).pdf

1051-mum-2007-form 8(23-10-2007).pdf

1051-mum-2007-form-1.pdf

1051-mum-2007-form-2.doc

1051-mum-2007-form-2.pdf

1051-mum-2007-form-3.pdf

1051-MUM-2007-MARKED COPY(25-11-2011).pdf

1051-MUM-2007-REPLY TO EXAMINATION REPORT(25-11-2011).pdf

1051-MUM-2007-SPECIFICATION(AMENDED)-(25-11-2011).pdf

1051-MUM-2007-SPECIFICATION(AMENDED)-(25-11-2011).tif

1051-MUM-2007-URDIP SEARCH REPORT(29-9-2010).pdf


Patent Number 250604
Indian Patent Application Number 1051/MUM/2007
PG Journal Number 03/2012
Publication Date 20-Jan-2012
Grant Date 12-Jan-2012
Date of Filing 04-Jun-2007
Name of Patentee INDIAN INSTITUTE OF TECHNOLOGY, BOMBAY
Applicant Address POWAI, MUMBAI
Inventors:
# Inventor's Name Inventor's Address
1 PROF SOLANKI CHETAN SINGH INDIAN INSTITUTE OF TECHNOLOGY BOMBAY, DEPARTMENT OF ENERGY SYSTEMS ENGINEERING, POWAI, MUMBAI 400076
2 SANGANI CHINTAN SURESHKUMAR INDIAN INSTITUTE OF TECHNOLOGY, BOMBAY, DEPARTMENT OF ENERGY SYSTEMS ENGINEERING, POWAI, MUMBAI 400076.
PCT International Classification Number H01L31/048
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA