This is the presentation of my final year Industrial training at CEL Ghaziabad

1. SOLAR PHOTOVOLTAIC CELL
Achyut Shukla
14th Aug 2013

2. About the company
• Central Electronics Ltd. is a public sector enterprise, under the
administrative control of the Dept. Of Scientific & Industrial
Research.
• CEL is a pioneer in the field of solar Photovoltaic in the country
and is today ranked among the first few in the world in this area of
activity. CEL is also credited with many firsts in the country,
professional Ferrites being one of them.
• CEL is presently engaged in the development, production and sale
of selected electronic components (Professional Ferrites,
Electronics Ceramics and Phase Shifters), selected electronic
systems, solar photovoltaic cells, modules and SPV systems and to
take up engineering development & production based on
indigenous technology developed through in house efforts or know
how from National Laboratories / Institutions.

3. Solar Energy
• Energy obtained from the sun is called solar energy.
Though low grade energy with temporal and spatial
variation is available from the sun, it is clean, cheap,
abundant and a very attractive alternate source of energy.
• Solar energy spectrum can be approximated by black body
spectrum at 5900 k (E Vs ).
• The energy of sun spectrum extends from 0.3 to 2.5 m of
wavelength and its peak is at wavelength of 0.5 m.
• Solar Energy received at the surface of the earth is around
1000W/m2 over an entire year.

4. Solar Photovoltaic Effect
• The photovoltaic effect is the means by which solar
panels or photovoltaic modules generate electricity
from light. A solar cell is made from a semiconductor
material such as silicon
• The operation of a photovoltaic (PV) cell requires 3 basic
attributes:
1. The absorption of light, generating either electron-hole pairs
or excitants.
2. The separation of charge carriers of opposite types.
3. The separate extraction of
those carriers to an external
circuit.

5. Solar Cell
A solar cell is any device that directly converts the energy in light into
electrical energy through the process of photovoltaic
The solar cell works in three steps:
1. Photons in sunlight hit the solar panel and are absorbed by
semiconducting materials, such as silicon.
2. Electrons (negatively charged) are knocked loose from their atoms,
causing an electric potential difference. Current starts flowing through
the material to cancel the potential and this electricity is captured. Due
to the special composition of solar cells, the electrons are only allowed
to move in a single direction.
3. An array of solar cells converts solar energy into a usable amount of
direct current (DC) electricity.

6. Specifications 4 inch round cells 5 inch Pseudo square cells
Isc 2.5 A 4.6 A
Voc 605 mV 605 mV
Pm(typical) 1.05 W 1.95 W
Pm with AR Coating
(Optional)
1.15 W 2.13 W
Modules wattage from 36 Cells
(Non AR Coated)
38 Wp 74 Wp
Types of Solar Cells

7. Fabrication Of Solar Cell

8. 1. Surface Preparation
• Wafers are cleaned to make it free from impurities
as these impurities may affect the electrical
performance of the solar cell.
• Polishing is to ensure that the wafer surface is free
from any saw cut marks.

9. 2. Texturisation or Alkaline Etching
• Texturisation is to get maximum absorption of sunlight
and uniform Texturisation surface on silicon wafer by
formation of tiny pyramids.
• When a ray of sunlight falls on the textured flat Silicon
Substrate and then due to pyramid multiple reflection
occur on pyramid surface which causes absorption of more
sunlight

10. 3. Diffusion
• This process forms a negative junction over the p-type
substrate. This, therefore, make a p-n junction.
• The texturised wafer is placed on printing chuck.
The diffusion paste is transferred on the silicon
wafer with the help of screen by using squeeze. The
printed wafers are then placed on the belt of
diffusion furnace by using tweezers. The diffused
wafers are then collected on the receiver &
undiffused wafer side is marked by quartz for
identifications of p-type.

11. 4. Edge Isolation or Plasma Etching
• The purpose of the plasma etching is to ensure that
n-type & p-type surface of the diffuse wafer are
isolated from each other
• Plasma materials attack the Stack of silicon wafer
unnecessary part of wafer will be affected and part
is removed.

12. 5. Anti Reflection Coating
• It reduces interference effects in reflected wave
from the anti-reflection coating out of phase with
the wave reflected from the semiconductor
surfaces.
• The thickness of the AR coating should be quarter
of the wavelength of incident wave.

13. • Comparison of surface reflection from a silicon solar cell, with and without a typical anti-
reflection coating

14. 6. Front Contact Printing
• The basic requirement of front contact are
1. Improving the current carrying capability.
2. Increasing the light collection by reducing the
shadowed area
• In Front contact printing two most important
parts of solar cell are made-
1. Grid of very fine circuit lines known as Fingers.
2. Larger collecting lines known as Bus-Bars.

15. Close up of a finished printed cell. Shows the grid and finger by top view and side
They have a spacing of about 3 mm.

16. 7. Back Contact Printing
• It is created on the rare side of solar cell (P side).
• It is mainly used for soldering purpose.
contact created on the rare side

17. 8. Firing
• This process ensures a good ohmic contact
between the paste and wafer otherwise no
current will flow through it. It also lowers the solar
cell resistance.
Solar Cell

18. Solar Modules
A module is simply an
array of solar cells in
series or parallel as per
electrical requirements
A solar module is the
power source of an SPV
system

19. Applications
1. Solar water pumping systems for irrigation or drinking purposes
A Solar Photovoltaic Water Pumping System essentially
consists of an SPV panel or array directly powering a
water pump. Water pumped during day can be stored in
the storage tanks for use during night. The generated
electricity from the SPV array is fed to the pump
through a switch. Normally low storage batteries are
provided, as the water can be stored in the storage tanks
if required.
SPV array

20. 2. Village power plant..
A view of 100 kWp Grid Interactive Power plant installed &
commissioned at Kalyanpur, Aligarh,
The power plants being
modular in nature can be
augmented in case of
increased demand for power.
3. Medical Refrigeration
Solar Powered Refrigerator
PV Modules for the
Solar Powered Refrigerators

21. 4. Industrial applications
A Cathodic Protection (CP) Station for Oil/Gas pipeline
Very Low Power TV Transmitter
Obstruction warning light at Airports
Far end System of the Solar Powered Railway Level
Crossing Radio warning System (SOLAGARD)

22. THANK YOU