MATERIALS FOR SOLAR ENERGY: SOLAR CELLS

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1 MATERIALS FOR SOLAR ENERGY: SOLAR CELLS ROBERTO MENDONÇA FARIA PRESIDENT OF Brazil-MRS (SBPMat)

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3 The concentration of CO 2 in Earth s atmosphere (2011) is approximately 392 ppm (parts per million) by volume, and rose by 2.0 ppm/yr during

4 In 2008, 8.67 gigatonnes of carbon (31.8 gigatonnes of CO 2 ) were released from fossil fuels worldwide, compared to 6.14 gigatonnes in 1990.

5 The Planet Today

6 Why Solar Energy? Today, the scientific evidence indicates that GHGs emissions from burning fossil fuels and other sources are causing rising Global Warming. To worsen this scenario, the world population growth and the continuous expansion of the individual energy consumption directly increase the amount of GHGs emission. Therefore, to maintain and to increase the access to energy services and to satisfy crucial needs required from the modern society, it is urgent the development of a sustainable global energy system to replace that of high GHGs emissions and unhealthy air pollutants. Solar energy generation is a renewable energy source that can play an important role in the future to reduce the amount of CO 2 emissions.

7 Why Solar Energy? Environmental Advantages. Solar power production generates electricity with a limited impact on the environment as compared to other forms of electricity production. Matching Peak Time Output with Peak Time Demand. Solar energy can effectively supplement electricity supply from an electricity transmission grid, such as when electricity demand peaks in the summer. Modularity and Scalability. As the size and generating capacity of a solar system are a function of the number of solar modules installed, applications of solar technology are readily scalable and versatile. Flexible Locations. Solar power production facilities can be installed at the customer site which reduces required investments in production and transportation infrastructure.

8 Solar Spectral Irradiance Two standard terrestrial spectral distributions (ASTM G173-03): the direct spectrum and the global.

9 The total irradiance just above the Earth s atmosphere is estimated to be approximately 174,000 TW. This is an amount of energy eight thousand more than the entire global consumption of energy in (average energy consumption was 15 TW)

10 Average Daily Solar Radiation at the Earth s Surface

11 How Does Solar Energy Create Electricity? Photovoltaic Device (or Solar Cell) can be an intelligent response.

12 Equivalent circuit for a Solar Cell I = Iph - ID

13 Current-Voltage characteristic of a solar cell

14 Photovoltaic Device or Solar Cell Operation Principle - pn junction

15 First generation Solar Cells: Homojunction (Crystalline Silicon, Amorphous Silicon, and GaAs)

16 Second generation Solar Cells: Heterojunction (CdTe, CIGS, and thin films of amorphous silicon) CdTe Cadmium telluride CIGS - Copper indium gallium selenide

17 Third generation Solar Cells: Tandem Solar Cell

18 Third generation Solar Cells: Bulk-heterojunction (Organic semiconductors very thin films) P3HT P3HT Poly(3-hexylthiophene) PCBM - [6,6]-phenyl-C 61 -butyric acid methyl ester PCBM

19 Third generation Solar Cells: Dye-sensitized cells

20 Third generation Solar Cells: Quantum dots InAs quantum dots

21 SC Generations max Lifetime Costs per W h Market First generation 30 % Decades $ 1 - $2 Commercial Second generation 20 % Decades $ 1 - $2 Near commercial Third generation 8 % 20,000 hours? In research

22 Cost efficiency analysis for first-, second-, and third-generation solar cell technologies.

23 PV efficiencies obtained for various materials and technologies

24 Current uses of PV solar panels

25 Solar-Photovoltaic Panels connected Residential to the electricity grid PV installations in houses and on buildings connected to the electricity grid has grown in recent years. Some government, as Germany and Japan, has subsidy programs to stimulate the use of solar energy.

26 Industrial Solar-Photovoltaic Panels connected to the electricity grid Solar energy can be an adequate solution for industrial applications, especially where power is required at remote locations. Because solar systems are highly reliable and require little maintenance, they are also ideal in distant or isolated places.

27 Building-integrated photovoltaics (BIPV) The concept of BIPV means more than just solar panels mounted on a roof. It is about creating inherent element of the shell structure of the building which works with general design concept whilst increases efficiency of the whole structure. BIPV adds value not only to economic model of the building but also to its architectural image.

28 Solar Power Plants - Photovoltaics There are several photovoltaic solar plants installed in different countries ( MW p ). In 2009, the global production reached more than 10 gigawatts (GW), but it represents a very small fraction of the world total energy consumption (less than 0.1 %).

29 Photovoltaic Market

30 Challenges for Giga and Terawatts scale Cost: prices must approach the cost of 4-12 cents per kwh; Efficiency: combined with the fabrication and maintenance costs, the efficiency must be improved; Lifetime: PV-produced electricity depends on how long the system continues to produce power at its rated level. The lifetime required to reach a cost equivalent to conventional electric power could be in the range 5-30 years; Scalability: This has to do with elemental abundance as well as the ability to process the materials quickly. Energy storage

31 THANK YOU