MONTH: OCTOBER ISSUE NO: 2015(3)

MAADHYAM

THEME

INSIDE HIGHLIGHTS:

Photovoltaic System

Recent Science Innovations

Research Institutes in India

News Corner

Nurturing Gifted Minds

Printed under Gifted Education Abhiyaan An initiative by the office of principal Scientific

Advisor to the Government of India

MONTH: OCTOBER ISSUE NO: 2015(3)

Silicon Wafers

Silicon is the second most

abundantly available material in

the earth’s Crust. The primary

source of silicon is quartzite,

found in ordinary sand.

A lot of energy is needed to

make a pure silicon wafer, which

is processed into a solar cell.

Silicon wafers are thin slices of

silicon that are used in integrated

circuits

Can you suggest any other

material instead of silicon to be

used in solar cells?

Now let’s explore about how solar energy or green energy is

converted into heat energy or electrical energy to fulfill energy

needs of our gene-next…..

What is photovoltaic system (PV)?

The term photovoltaic system (PV) is a combination of two words –photo, meaning light, and

voltaic, meaning electricity. PV technology refers to the hardware that converts incident

sunlight into usable electricity. At the core of PV technology is a semiconductor material that

undergoes an electronic process to release electrons. These negatively charged particles form

the basis of electricity production. The device that does this simple but inherent complex

function is known as solar cells.

Why are most of solar

cells made up of silicon?

What are silicon wafers?

In the last issue we have

discussed a lot of

information about Sun as

a source of energy and its

application in our day to

day life.

MONTH: OCTOBER ISSUE NO: 2015(3)

1. Preparation of crucibles: Silica crucibles are coated with an anti-adhesion material to

prevent molten silicon from adhering to them. Once the coating is complete, the crucibles

are baked for 24 h at high temperature in a kiln.

A crucible is a container that can withstand very high temperatures.

A kiln is a thermally insulated chamber.

2. Preparation of poly-silicon: the recycled polysilicon feedstock from previous growth as

well as newly purchased stock is cleaned (sand blasted and etched). It is then

characterized for resistivity and conductivity type. The target resistivity of the first 10

mixtures and the amount of dopant needed are automatically calculated by the system.

3. Loading of the crucibles: the crucibles are manually loaded by an operator with utmost

care, without scratching and coating.

4. Growth of ingot: a furnace known as the directional solidification system is used for

melting upto 450 kg of silicon in a crucible and grows a multi-crystalline ingot. The size

of the ingot and its cycle time varies from one case to another.

5. Sectioning the ingot: a wire saw is used to cut the ingot into blocks, known as bricks, of

suitable size.

6. Cropping the bricks: the top and bottom of the bricks are removed with a wire saw. The

top piece is discarded as it contains contaminants and the bottom is recycled (used for the

next growth run). The yield loss due to wafer breakage is reduced by polishing the brick

surfaces prior to sawing.

7. Wafering the ingot: the silicon bricks are glued to a glass carrier beam, which is

mounted in a wire saw. A wire saw generally has four cutting tables, each populated with

two blocks.

8. Cleaning the wafer: wafer cleaning comprises a pre-clean step and a final cleaning step.

In the pre-clean step, the cut wafers, still glued to the glass carrier beam, are cleaned from

most of the slurry using a hot ultrasonic detergent bath and rinsed in deionized water. The

final steps include alkaline cleaning and optional acidic cleaning. The wafer leaves the

system as a dry cleaned piece.

9. Characterization of wafer: the wafers are finally tested for proper thickness, thickness

variation, resistivity, and other parameters; they are then sorted into stacks.

The manufacturing process of silicon wafers (very thin slices of silicon) is described as:

MONTH: OCTOBER ISSUE NO: 2015(3)

The most important part of a PV system is the solar cell, which collects

sunlight. These form the basic building blocks of the modules which

ultimately run the PV. Solar cells are usually made either from crystalline

silicon (sliced from ingots or castings) or from growth ribbons.

1. Inspection of wafer: multi-crystalline wafers meeting specified characteristics are

unpacked and tested for basic properties such as resistivity and continuity.

2. Etching and texturing: cutting silicon into wafer leaves the surface covered with cutting

slurry. The surface is also damaged due to the action of the wire saw. The wafers are

cleaned in a hot solution of sodium hydroxide, which removes surface contamination and

other impurities.

3. Phosphorus dopping and emitter diffusion: the etched texturized wafer is transported

through a furnace, where phosphorus is diffused into the silicon wafer to provide the

emitter or P-N junction in common terms.

4. Phosphorus glass etching and emitter isolation: during the diffusion process, an oxide

is formed on the surface of the wafer. It is removed in a wet bench containing acid.

5. Rear side passivation: rear side passivation is obtained using aluminium oxide (Al2O3)

passivation layer in combination with silicon nitride (SiNx). The improved passivation of

the rear side of the cell as compared to conventional cell structure results in lower carrier

recombination, thus improving the cell performance.

6. Front side passivation: an anti-reflection coating is applied on the front of the cell in a

plasma-enhanced chemical vapour deposition (PECVD) reactor by applying plasma of

ammonia and silane, which forms silicon nitride. The cell acquires passivation property

and anti-reflective property by this method.

7. Annealing of the cell: in order to create charge separation between the interface of SiNx

and Al2O3, the cell is processed through heat chamber after the passivation process.

8. Laser action: lasers are used to drill holes to create contact area for the aluminium paste

with silver.

9. Screen printing: the solar cells are passed through a screen printer. Here, a silver paste is

used for printing the fine grid of metal contacts on the front side and aluminium paste on

the rear side of the cell.

10. Drying and firing: the screen printed cells are passed through a high temperature

furnace in a controlled manner so as to embed the contacts into its body.

11. Cell sorting, transferring, and sorting: the solar cells are finally cleaned and air-dried.

They are then automatically tested for their electrical characteristics and then sorted on

the basis of the properties

Solar Cells

The photovoltaic cells are manufactured by following steps:

MONTH: OCTOBER ISSUE NO: 2015(3)

APPLICATIONS OF PHOTOVOLTAIC SYSTEMS

Off grid systems for residential use such as solar home lighting systems and street lighting systems. These are also known as stand-alone systems.

Off-grid industrial power systems such as those used for water management, lighting, and telecommunications.

Small capacity grid connected PV systems such as those that can be integrated in roofs (that is, rooftop systems) and outer walls of a building or in noise barriers along highways. Building integrated PV is one of the fastest upcoming applications.

Megawatt-scale PV grid power plants such as large-sized solar farms and others directly connected to a locally available grid.

MONTH: OCTOBER ISSUE NO: 2015(3)

Bionic Leaf- Makes fuel from sunlight...

Let’s Explore About Recent Science Innovations in Solar Energy

Scientists from Harvard University's Faculty of Arts and

Sciences, Harvard Medical School and the Wyss Institute

for Biologically Inspired Engineering at Harvard University

recently created a bionic leaf, which uses a catalyst to

make sunlight split water into hydrogen and oxygen, then a

bacteria engineered to convert carbon dioxide and hydrogen

into a liquid fuel called isopropanol. They're almost at a 1%

efficiency rate of turning the sunlight into the fuel — in

other words; they've found a way to recreate the

efficiency of photosynthesis.

To Read More please

Visit:

http://harvardmag

azine.com/2015/0

5/the-bionic-leaf

https://hms.harvar

d.edu/news/bionic

-leaf

http://cleantechnic

a.com/2015/02/12/

harvard-scientists-

invent-bionic-leaf-

makes-rubbing-

alcohol/

Fig . The "bionic leaf" – a solar–to–chemical

conversion system – uses solar power to split

water into hydrogen and oxygen, which is

then fed to engineered bacteria that can

combine hydrogen with carbon dioxide to

produce liquid fuel isopropanol.

Source:http://wyss.harvard.edu/viewpressrelease/189/bionic-leaf-uses-bacteria-to-convert-solar-energy-into-liquid-fuel

Solar Energy-Harvesting 3 D Printed

Trees Can we imagine having trees around us providing charging

points? If possible, this would make people plant more and

more trees willingly! Scientists at VTT Technical Research

Centre of Finland have made the model of such a tree whose

leaves can produce electricity.

Scientists at VTT Technical Research Centre of Finland have

developed the prototype of Solar Energy Harvesting Tree.

The leaves of conventional trees perform photosynthesis to

convert light energy into chemical food energy. Analogically,

leaves of VTT’s tree convert energy from surroundings into

electricity for low power devices.

Fig 3D Printed Tree

Source:http://fossbytes.com/vtt-developed-

solar-energy-harvesting-trees

MONTH: OCTOBER ISSUE NO: 2015(3)

To read more please

visit:

http://fossbytes.c

om/vtt-

developed-solar-

energy-

harvesting-trees

http://3dprint.co

m/45558/finnish-

3d-printed-solar-

trees

http://www.vttres

earch.com/media

/news/solar-

power-from-

energy-

harvesting-trees

Figure 3. Vision of Space Solar

Power System (SPSS)

Source: Jaxa’s Vision of Space Solar

Power System (SPSS)

The leaves of the tree are made up of flexible solar panels. They

are fabricated of printed organic photo-voltaic cells. These

comprise of conductive organic molecules which absorb light,

transfer charge and produce electricity using photo-voltaic

effect. However, the leaves of VTT’s energy harvesting trees

convert energy from multiple sources. They absorb solar energy

from indoors as well as outdoors. The leaves use light energy

along with energy due to temperature fluctuations and pulsation

triggered by winds. Leaves are infinitely replicated and each leaf

has discrete multi-converter system. The trunks of trees are

made of 3D printed bio-composites.

Energy is stored and then converted into electricity for small

power devices such as cell phones, thermometers, humidifiers and

LED lights. Researchers are looking forward to the day when

forests of such solar energy harvesting trees can be employed to

perform on larger scales.

Is It Possible to

Construct Solar power

station In Space?

Japan Hopes To

Have Solar Power

Transmission in

Space By 2030

The Japan Aerospace Exploration Agency (Jaxa) hopes that

the ambitious plans will help to ease the country’s energy

problems as well as providing a solution for global warming.

The plan is to create a miles-wide array of photovoltaic

panels, like the solar panels used on Earth, and place it in a

geostationary orbit.

Solar rays are at least five times as powerful

in space as they are at ground level, allowing the huge

panels to gather vast quantities of energy.

Figure Vision of Space Solar Power System

(SPSS)

Source: Jaxa’s Vision of Space Solar Power

System (SPSS)

MONTH: OCTOBER ISSUE NO: 2015(3)

SERIIUS—The Solar Energy Research Institute for India and the United States—is co-led by the Indian Institute of Science (IISc)—Bangalore, India, and the National Renewable Energy Laboratory (NREL), Golden, Colorado, USA.

Through an environment of cooperation and innovation "without borders," SERIIUS will develop and ready emerging and revolutionary solar electricity technologies—toward the long-term success of India's Jawaharlal Nehru National Solar Energy Mission and the U.S.

Department of Energy's Sun Shot Initiative.

SERIIUS will accelerate the development of solar electric technologies by lowering the cost per watt of photovoltaics (PV) and concentrated solar power (CSP). To read more please visit: http://www.seriius.org/

Fig: “Space Based Solar Power”

Source:http://billionyearplan.blogsp

ot.in/2010_08_01_archive.html

To Know more please visit:

http://news.discovery.com/space

/japan-solar-space-station.htm

http://spectrum.ieee.org/green-

tech/solar/how-japan-plans-to-

build-an-orbital-solar-farm

http://www.pocket-

lint.com/news/128894-japan-s-

jaxa-plans-to-build-a-solar-

power-station-in-space-by-2030

Solar Energy Research Institutes in India

India Need More Scientists for Future Innovations in Field of

Solar Energy – Let’s Explore About Some Solar Energy

Research Institutes in India

MONTH: OCTOBER ISSUE NO: 2015(3)

The Ministry of New and Renewable Energy (MNRE) is the nodal Ministry of the Government of India for all matters relating to new and renewable energy. The broad aim of the Ministry is to develop and deploy new and renewable energy for supplementing the energy requirements of the country.To read more please visit: http://nise.res.in

Sardar Patel Renewable Energy Research Institute (SPRERI) - A leading organization for research and development of renewable energy (RE) technologies, focuses on sustainable biomass conversion and solar energy based solutions, which are technically efficient, economically viable, environment friendly and which meet the needs of society.SPRERI is recognized by S.P. University, Vallabh Vidyanagar, Junagadh Agricultural University, Junagadh, Nirma University, and Ahmadabad as a Centre for M.Tech and Ph.D. Research.To read more please visit: http://www.spreri.org/

TERI ( The Energy and Resources Institute) – “Creating Innovative Solutions for a Sustainable Future.”

Tackle issues of concern to Indian society, and the world at large, and develop innovative and cost effective solutions.

Enhance networking for sustainable interventions.

Realize potential for national and international leadership as a knowledge based agent of change in the fields of energy, environment, other natural resources and sustain able development.

Inspire and reach out to diverse stakeholders for realising a shared vision of global sustainable development could be translated into action.

TERI, since 2001, annually organizes the Delhi Sustainable Development Summit (DSDS), an international platform to facilitate the exchange of knowledge on all aspects of sustainable development.

To read more please visit: http://www.teriin.org/

Interdisciplinary Centre for Energy Research (ICER) – ICER was set up in 2012. Research in Energy is interdisciplinary by its nature and needs expertise in many different domains. Taking into consideration the strengths of the Institute in various fields related to Energy and the present need for the country in Energy Research, IISc has created this interdisciplinary center. A wide range of research activities related to Energy are already being carried out by individual faculties, which is already serving as a base for energy research.

Under ICER, research on various fields, such as Concentrating Solar Power (CSP), Next-Generation Solar PhotoVoltaic (PV), High Storage Density Battery, Green Buildings, Sustainable Technologies, Combustion Science and Technology.

ICER provide PhD degree program in all areas of research in Energy Science and Technology including novel concepts of Energy Harvesting and Efficiency, developments of tools and systems for Solar, Thermal and other sources of energy.

To read more please visit: http://www.icer.iisc.ernet.in/admissions/interdisciplinary.htm

MONTH: OCTOBER ISSUE NO: 2015(3)

Maadhyam News Corner

Plan to honey trap dengue mosquitoes (Sterile Male

Insects to Slow down Breeding)

Scientists are planning to alter genetic composition of the

male mosquito. Male mosquitos infected with sterility-

causing bacteria and these Genetically Modified (GM)

mosquitoes will mate with the female (dengue causing)

mosquito. The resulting eggs contain the sterile gene. The

larva dies before developing into pupa, thus controlling the

population of dengue causing mosquito ( Aedes aegypti).

This technique has been tried successfully in a small island in

southern China where GM mosquitoes are being used to

reduce the population of dengue causing mosquito.

To read more: Times of India (13th Oct 2014) /

http://timesofindia.indiatimes.com/

Deleting genes could extend lifespan

Researchers have identified 238 genes linked to aging

and found that switching them off extends life in yeast

cells, an advance that provides new genomic targets

which could be used to boost human life span. Many of

genes are present in mammals, including humans,

suggesting that switching them off could dramatically

increase lifespan.

To read more: Times of India (13th Oct 2014) / http://timesofindia.indiatimes.com/

http://www.thebuck.org/

World’s smallest free-living bug is just 0.32 mm

A minute feather wing beetle found in Colombia and

Nicaragua is the world‟s smallest free-living insect,

measuring an astounding o.325 mm.

To read more: Times of India (13th Oct 2014) /

http://timesofindia.indiatimes.com/

http://www.msu.ru/en/

Soon, a tree-planting drone to counter deforestation

British engineering firm is seeking international

backing to develop the first automated tree-planting

drones in order to help counter deforestation across the

world.

To read more: Times of India (13th Oct 2014) /

http://timesofindia.indiatimes.com/

One in 13 World Cancer Patient is Indian: US

study

The National Cancer Institute (NCI), a unit of US

Department of Health and Human services

(USDHHS), has observed that India shares a large

proportion of the global cancer burden, with

dissemination of scientific information among the

general populace.

To read more: Times of India (13th Oct 2014) / http://timesofindia.indiatimes.com/ www.cancer.gov/

1st „in womb‟ stem cell trial next year (To Be Injected Into

Fetuses to Lessen Brittle Bone Disease Symptoms)

The first clinical trial to inject fetal stem cells into babies still

in the womb to lessen the symptoms of incurable brittle bone

disease will begin in January next year. The trial will be led

by sweden‟s karolinska Institute and in the UK by Great

Ormond Street Hospital and the stem cells will come from

terminated pregnancies. Officially called osteogenesis

imperfect, brittle bone disease affects around one in every

25,000 births.

To read more: Times of India (13th Oct 2014) /

http://timesofindia.indiatimes.com/

http://ki.se/en/startpage

MONTH: OCTOBER ISSUE NO: 2015(3)

RESPONSE SHEET

1. If you have to do some innovation in solar energy research or renewable energy research, what new you will plan

to fulfill energy needs of future generation?

___________________________________________________________________________________________

___________________________________________________________________________________________

___________________________________________________________________________________________

___________________________________________________________________________________________

2. What can other countries learn from Japan mission to set up Solar Power Transmission in Space By 2030?

___________________________________________________________________________________________

___________________________________________________________________________________________

___________________________________________________________________________________________

___________________________________________________________________________________________

3. Is it possible to create forest of Solar Energy-Harvesting 3 D Printed Trees? Give your opinion on this latest

innovation of VTT Technical Research Centre of Finland.

___________________________________________________________________________________________

___________________________________________________________________________________________

___________________________________________________________________________________________

___________________________________________________________________________________________

If you are given an

opportunity to pursue

research work, what will be

your area of interest?

MONTH: OCTOBER ISSUE NO: 2015(3)

YOUR FEEDBACK:

My Name: _______________________________________________

I am in class: __________________

From School: ______________________________________________

Areas well explained in this issue:

____________________________________________________________

____________________________________________________________

____________________________________________________________

Areas need more explanation in this issue:

____________________________________________________________

____________________________________________________________

____________________________________________________________

Suggest next Theme:

____________________________________________________________

Any other:

____________________________________________________________

____________________________________________________________

____________________________________________________________

____________________________________________________________

____________________________________________________________

RESEARCH TEAM

Geetu Sehgal , Shilpi

Bariar, Jyoti Batra,

Uzma Masood ,Ritu

Verma,Meenakshi

Gifted Education Abhiyaan Project Team

Dr. Jyoti Sharma

Prof. Pankaj Tyagi

Prof. Shobha Bagai

Prof. Bibhu Biswal

Email id: giftededucationcic@gmail.com