1. SOLAR ENERGY History Advantages and disadvantages Solar energy system Lai Liulin Lu Yile

2. History 1838 Edmund Becquerel observed the nature of materials to turn light into energy. 1873 Willoughby Smith, a Brit, experimented with the use of selenium solar cells 。 1883 Charles Fritz turned the sun's rays into electricity. His solar cell had a conversion rate of only 1-2%. 1885 - 1889 Charles Tellier installed the first solar energy system for heating household water on top of his very own roof. 1892 - 1905 Aubrey Eneas formed the first Solar Energy company - The Solar Motor Co. They sold the first Solar Energy system to Dr. A.J. Chandler of Mesa, Ariz for $2,160.

3. History 1954 Calvin Fuller, Gerald Pearson and Daryl Chaplin of Bell Laboratories accidentally discovered the use of silicon as a semi-conductor, which led to the construction of a solar panel with an efficiency rate of 6%. 1950s - 1960s Space programs employed solar technologies. In 1958 the Vanguard I was launched. The first satellite that used solar energy to generate electricity. 1970 The Energy Crisis ! (OPEC oil embargo). Suddenly it became important to find an alternative form of energy as we realised just how reliant we really are on non-renewable, finite resources like coal, oil and gas for our existence. Solar energy history was made as the price of solar cells dropped dramatically to about $20 per watt.

4. History 1980 - 1991 A Los Angeles based company called Luz Co. produced 95% of the world's solar-based electricity. They were forced to shut their doors after investors withdrew from the project as the price of non-renewable fossil fuels declined and the future of state and federal incentives were not likely. The chairman of the board said it best: "The failure of the world's largest solar electric company was not due to technological or business judgment failures but rather to failures of government regulatory bodies to recognize the economic and environmental benefits of solar thermal generating plants."

5. Advantages & disadvantages Pros: Money saving Low margin cost: the energy from the sun is practically FREE Support from the government: financial incentives Reduce the health costs: positive externality Environmentally friendly Renewable and sustainable: help to protect the environment from over –exploitation No pollution: doesn’t release carbon dioxide, nitrogen oxide, sulphur dioxide or mercury into the atmosphere; makes no contribution to acid rain, smog and global warming. No fuel: does not contribute to the cost and problems of the recovery and transportation of fuel or the storage of radioactive waste.

6. Advantages & disadvantages Pros: Independent/ semi-independent Operate independently: not requiring a connection to a power or gas grid at all. Systems can therefore be installed in remote locations (like holiday log cabins), making it more practical and cost-effective than the supply of utility electricity to a new site. Energy independent ： The use of Solar Energy reduces the dependence on foreign and/or centralized sources of energy, influenced by natural disasters or international events and so contributes to a sustainable and stable future.

7. Advantages & disadvantages Cons: Large initial cost: largely because of the high cost of the semi-conducting materials used in building one Footprint: Solar panels require quite a large area for installation to achieve a good level of efficiency. Dependence on the nature: The efficiency of the system also relies on the location of the sun, although this problem can be overcome with the installation of certain components. The production of solar energy is influenced by the presence of clouds or pollution in the air. Similarly, no solar energy will be produced during nighttime although a battery backup system and/or net metering will solve this problem.

8. Solar energy system solar water heating As seen in the name, it is used to heat water. Designs are suitable for hot climates places Usually used in a residential setting to provide hot domestic water China has the largest amount of installment in the world.

9. Solar energy system solar water heating Passive system –use water from the main household water supply to circulate between the collector and the storage tank. When the water in the collector becomes warm, convection causes it to rise and flow towards the water storage tank –the storage tank must be located above the collector so that the thermosiphon effect can transport water or HTF from collector to tank. –The attraction of passive solar water heating systems lies in their simplicity. There are no mechanical or electrical parts that can break or that require regular supervision or maintenance.

10. Solar energy system solar water heating Active system –employ a pump to circulate water or HTF between the collector and the storage tank. –The storage tank can be situated lower than the collectors. –Modern active solar water systems have electronic controllers that permit a wide range of functionality such as full programmability ensures the water always gains heat from the collector when the pump operates and prevents the pump from cycling on and off too often. –Reducing the risk of overheating and freezing

11. Solar energy system photovoltaic (PV) PV are best known as a method for generating electric power by using solar cells to convert energy from the sun into electricity. Solar cells produce direct current electricity from sun light, which can be used to power equipment or to recharge a battery.

12. How does PV work? 1.Rays of sunlight hit the PV and are absorbed by semi-conducting materials such as silicone 2.Electrons are knocked loose from their atoms, which allow them to flow through the material to produce electricity. This process whereby light is converted into electricity is called the PV effect. 3.An array of PV converts solar energy into DC (direct current) electricity. 4.The DC electricity then enters an inverter. 5.The inverter turns DC electricity into AC (alternating current) electricity needed by home appliances. 6.The AC power enters the utility panel in the house. 7.The electricity (load) is then distributed to appliances or lights in the house. 8.When more solar energy is generated that what you're using - it can be stored in a battery as DC electricity. The battery will continue to supply your home with electricity in the event of a power blackout or at nighttime. 9.When the battery is full the excess, electricity can be exported back into the utility grid, if your system is connected to it. 10.Utility supplied electricity can also be drawn form the grid when not enough solar energy is produced and no excess energy is stored in the battery, i.e. at night or on cloudy days. 11.The flow of electricity in and out of the utility grid is measured by a utility meter, which spins backwards (when you are producing more energy that you need) and forward (when you require additional electricity from the utility company). The two are offset ensuring that you only pay for the additional energy you use from the utility company. Any surplus energy is sold back to the utility company. This system is referred to as "net-metering" http://www.youtube.com/watch?v=2mCTSV2f36A

13. Thanks for your attention