This document summarizes a seminar presentation on photovoltaic cells. The presentation covered: - An introduction to photovoltaics, which are semiconductor devices that convert sunlight to direct current electricity. PV cells are arranged into modules and arrays. - A brief history of PV cells including early uses to power satellites and navigational aids in the 1950s-1960s and later consumer electronics. - The 9-step production process for silicon wafer-based PV cells including pre-treatment, texturing, diffusion, anti-reflective coating, contact printing, and final testing and sorting.

1. Seminar on
“Photo-voltaic cells”
By
Chetan hiwase
Roll Number: 173510
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2. PHOTO-VOLTAIC CELLS
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3. INTRODUCTION
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 Photovoltaics (PV) or solar cells are semiconductor
devices that convert sunlight into direct current (DC)
electricity.
 Groups of PV cells are electrically configured into
modules and arrays, which can be used to charge
batteries, operate motors, and to power any number of
electrical loads.
 With the appropriate power conversion equipment, PV
systems can produce alternating current (AC)
compatible with any conventional appliances, and can
operate in parallel with, and interconnected to, the
utility grid

4. INTRODUCTION
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5. HISTORY OF PV CELLS
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1960-1970:
Battery charging for navigational
aids
1950-1960:
Earth Orbiting Satellites
1980:
Consumer electronic devices

6. HISTORY OF PV CELLS
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7. PV CELLS COST
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8. 8
Trend of growth in PV cells

9. Working of PV cells
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10. CELLS, MODULES AND ARRAYS
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11. TYPES OF PV CELLS
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Made by using
crystalline solid solar
cells, developed from
micro electronics
technology industry
Mono crystalline PV
cells
Multi crystalline PV
cells
 Made by depositing one
or more thin photo
voltaic material on
substrate
 Amorphous silicon PV
cells
 Poly crystalline PV cells

12. 12
Production of PV cells
from silicon-wafers

13. • Raw silicon wafer- pre-check - geometric
shape and thickness conformity and damages such as cracks,
breakages, scratches or other anomalities.
• Then the wafers are split and cleaned with industrial soaps to
remove any metal residues, liquids or other production
remains from the surface that would otherwise impact the
efficiency of that wafer.
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Step 1: Pre-check and Pretreatment

14. STEP 2: TEXTURING
• textured to reduce reflection losses random
pyramid texturing.
• regular, neat atomic structure
• flow of electrons 14

15. Step 3: Acid Cleaning
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• acidic rinsing means remove the post texturing
particles which remains their.
• hydrogen flouride (HF) vapor
• hydrogen chloride (HCl)

16. Step 4: DIFFUSION
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• Adding dopant so it is more electrically conductive.
• There are basically 2 methods of diffusion: solid state
Diffusion (p type, boron) and emitter diffusion.(Dopant
material-containing coating) by passing through
Diffusion coating furnace.
• The junction of electron deficiency in the p-type and
high electron concentration in the n-type allows for
excess electrons from the n-type to pass to the p-type,
a flow creating an electron field at the junction.

17. Step 5: Etching & Edge Isolation
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• The n-type phosphorous diffuses not only into the
desired wafer surface but also around the edges of the
wafer as well as on the backside, creating an electrical
path between the front and back side and in this way also
preventing electrical isolation between the two sides.
•The objective of the etching and edge isolation process
is to remove this electrical path.

18. Step 6: Post-Etching Washing
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• After the etching, particle residues potential remain on
the wafer and the wafer edges. Therefore the wafers
need to undergo a second washing to remove remains of
the previous etching process.
•After this second washing, the wafers can further be
processed for the deposition of anti-reflective (AR)
coating.

19. Step 7: Anti-Reflective Coating Deposition
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• Anti-Reflective Coating reduce reflection and increase
the amount of light absorbed into the cell.
•Anti-Reflective Coating silicon nitride (Si3N4) or titanium
oxide (TiO2) is used.
•The colour of the solar cell can be changed by varying
the thickness of the anti reflection coating.

20. Step 8: Contact Printing and Drying
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• metal inlines are printed on the wafer with the objective
to create ohmic contacts. These metal inlines are printed
on the rear side of the wafer, which is called backside
printing.
• The wafer undergoes a drying process.
•After all contacts have been printed on the rear and front
sides, the screen-printed wafers are passed through
a sintering furnace to solidify the dry metal pastes onto
the wafers. Then, the wafers are cooled.

21. Step 9: Testing and Cell Sorting
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In this final process, the now ready-to-assemble solar
cells are tested under simulated sunlight conditions and
then classified and sorted according to their efficiencies.
This is handled by a solar cell testing device that
automatically tests and sorts the cells.

22. THANK YOU
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