Sascha Stegen

School of Electrical Engineering,

Griffith University, Australia

� Diameter of 1,390,000km

� Average mass density of 1.41 g/cm^3

� Average distance to Earth 150,120,000 km (108 times the Sun’s diameter or 8.19 light minutes….)

� Hot plasma from ionised Atoms

� Highest Temperature of approx. 23 82 106 K

� Fusion of Hydrogen

1. Core: 20–25% of the solar radius. It has a density of up to 150 g/cm3. With 276.5 watts/m3,a power density that more nearly approximates reptile metabolism than a thermonuclear bomb.

2. Radiate zone3. Convective zone4. Photosphere5. Chromosphere6. Corona7. Sunspot8. Granules9. Prominence

http://en.wikipedia.org/wiki/File:Sun_diagram.svg

� Convective zoneConvective zoneConvective zoneConvective zone◦ from its surface down to approximately 200,000 km

(or 70% of the solar radius)

� PhotospherePhotospherePhotospherePhotosphere◦ particle density of ~1023 m−3

◦ Emitting of the highest content of visible light

� AtmosphereAtmosphereAtmosphereAtmosphere◦ Emission of highly ionised Metal atoms

http://en.wikipedia.org/wiki/File:Sun_parts_big.jpg

Energy

Particles

Protons Neutrons Positrons Neutrinos

�

����� � ∆� ∙

���� =4.3 ∙ 10 ���

������ =

�����

�=3.845 ��

� Applying of the Stefan-Boltzmann-Law for the Sun as a black body, provides the surface temperature of the Sun

� Specific radiation from the Sun’s surface As

�� �

�� � �

� Global rays◦ The sum of direct rays

and sky rays

� Sky rays◦ Produced by diffusion of

direct sun rays through air molecules

Active system

June

June

Dec

Dec

Glo

bal

su

n r

ays

in W

/m^2

Time

� The term "photovoltaic" comes from the Greek φῶ̋ (phōs) meaning "light", and "voltaic", from the name of the Italian physicist Volta, after whom a unit of electro-motive force, the volt, is named. The term "photo-voltaic" has been in use in English since 1849.[1]

� The photovoltaic effect was first recognized in 1839 by French physicist A. E. Becquerel. However, it was not until 1883 that the first photovoltaic cell was built, by Charles Fritts, who coated the semiconductor selenium with an extremely thin layer of gold to form the junctions. The device was only around 1% efficient. In 1888 Russian physicist Aleksandr Stoletov built the first photoelectric cell based on the outer photoelectric effect discovered by Heinrich Hertz earlier in 1887.[2]

� Albert Einstein explained the photoelectric effect in 1905 for which he received the Nobel prize in Physics in 1921.[3] Russell Ohlpatented the modern junction semiconductor solar cell in 1946,[4]

which was discovered while working on the series of advances that would lead to the transistor.

http://en.wikipedia.org

� The modern photovoltaic cell was developed in 1954 at Bell Laboratories. The highly efficient solar cell was first developed by Daryl Chapin, Calvin Souther Fuller and Gerald Pearson in 1954 using a diffused silicon p-n junction. At first, cells were developed for toys and other minor uses, as the cost of the electricity they produced was very high; in relative terms, a cell that produced 1 watt of electrical power in bright sunlight cost about $250, comparing to $2 to $3 for a coal plant.

http://en.wikipedia.org

� Mono–crystalline solar cells

� Poly–crystalline solar cells

� Thin film solar cells

� Organic solar cells

Source : National Renewable Energy Laboratory (NREL), Golden, CO, Author: L.L. Kazmerski

Next generation: …more quantitative then qualitative. No norm.

Difference regarding M. Green:

� Gen. I: Wafer-based mono cristalline

� Gen. II: Thin-Film (strongly reduced costs, moderate efficiency)

� Gen. III: Efficiency increase of factor 2-3

Source: M.Green

http://www.windsolarpowerhome.com/

� Batteries optional

� Feeding back to the grid

� LV consumers can be fed directly

Light gets absorbed by the semiconductor

Production of mobile charge carriers

Dividing of the charge carriers

Electrical voltage on the contacts is now measurable

Contact grid

Glass layer

Buffer layer

Light absorber

Back contact

Substrate

http://www.sharpdirect.co.uk/page/solarhowpvmodules/

� +

�� � 0�� � ��

��+����

�� � �� ��� !� " # 1

k is the dielectric constant

q is the electrical charge

n is the quality factor

� �$ �% �&

'� ( � 11 ) �*�&�+,/�."

( � (/ → '� ( � 12( ≪ (/ → '� ( �1( ≫ (/ → '� ( �0

4� 5 6�$ 7�% 5 6�&

4� � 487� � 484�7� � 48�

48 ∝ �&��"

48*300;, � 10<�=�&>

4� 5 6�$

7� � 48�6�$

4�7� � 48�

48*300;, � 10<�=�&>4� 5 6�$ 5 10<?=�&>

7� � 10>=�&>

7� 5 6�&

4� � 48�6�&

4�7� � 48�

48*300;, � 10<�=�&>7� 5 6� 5 10<?=�&>

4� � 10>=�&>

Constant

fermi level

Propotional to the electric field

Ec=-qV

poN≈!@AB

noP≈!@A

CD � EFC G46�6�4�

D~(I

D� � 0k is the dielectric constant

q is the electrical charge

n is the quality factor

poN≈!@AB

noP≈!@A

J� � �&∆��."

� Lowering the energy barrier

J � J���� �."

� The avarage time tn is the time for an electron to recombine (or diffuse) on the p-side.

�� � ����+

����

K! � CL ∆4M N ONP��

� If a minority electron recobines on the p-side, one electron goes into the conductor

� Injected current produces a population of electrons in the P region

� The electrons recombine inside the P region

� If an electron recombines with a hole, another electron is flowing through the conductor

�� � �� ��*�B&QBRS�." # 1

D� � D�+��TU

TU

� �

88%

Energy flux - E

Work / Unit time - W

Heat flux - Q

Entropy flux – Q/TA

Entropy flux due to conversion - SG

Source: M.Green

(Maximum for SG=0)

But:

- Carnot-Efficiency factor can not be reached

Source: M.Green

http://www.pvsolarchina.com/difference-between-monocrystalline-

polycrystalline-and-amorphous-thin-film-solar-cell.html

http://cnfolio.com/ELMnotes15

http://blogs.reuters.com/from-

reuterscom/2009/10/06/graphic-thin-film-solar-cells/

http://www.sciencedirect.com/science/article/pii/S0927024806002509

AR – anti-reflective or anti-reflection coating

source:Hahn-Meitner-Institut Berlin

http://inhabitat.com/super-cheap-solar-cells-switch-gold-for-nickel/

� High efficacy and low costs

5.14 MWh Solar radiation

Instead of 7.14 MWh

in the Solar thermal

power plant

2.07 MWh Collector losses

0.61 MWh Receiver losses

1.36 MWh circle losses

0.11 MWh Internal consumptions

1 MWh Electrical energy

� different and much more efficient thanphotovoltaic PV solar cells

� While existing generation facilities provide only 600 megawatts of solar thermal power worldwide in October 2009, plants for an additional 400 megawatts are under construction and development is underway for concentrated solar power projects totaling 14,000 megawatts

http://upload.wikimedia.org/wikipedia/commons/3/31/Transpired_Air_

Collector.PNG

� More affordable than with traditional solar cells

� Allreadyrealised in large scale installations

7.14 MWh Solar radiation

3.36 MWh Solar losses

2.68 MWh Circulation losses

0.11 MWh Internal consumptions

1 MWh Electrical energy

� Jha, A.R.. Solar Cell Technology and Applications.BocaRaton, FL, USA: Auerbach Publications, 2009

� Martin A. Green: „Solar Cells: Operating Principles, Technology, and System Applications“

� Solar Electric Power Generation - Photovoltaic Energy Systems - Modeling of Optical and Thermal Performance, Electrical Yield, Energy Balance, Effect on Reduction of Greenhouse Gas Emissions, Search Within, By: Krauter, Stefan C.W. 2006 Springer – Verlag

� Nanotechnology for Photovoltaics by Loucas Tsakalakos, CRC Press 2010, Print ISBN: 978-1-4200-7674-5, eBook ISBN: 978-1-4200-7675-2

� Video clips are from www.youtube.com