Part of 2R's project on renewable energy.

1. solar energy By Elyse and jeong

2. what solar power is Solar energy, is a radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation, along with secondary solar-powered resources such as wind and wave power, hydroelectricity and biomass, account for most of the available renewable energy on earth. Only a minuscule fraction of the available solar energy is used.

3. how solar energy is harnessed Every year the Earth receives energy in abundance. This energy drives processes in the atmosphere that cause the wind and waves. Some energy is absorbed by green plants and used to make food by photosynthesis. So, ultimately, the Sun is the source of most energy resources available to us, including fossil fuels. Solar energy can be used to heat a fluid such as water in solar collector panels. Simple types use flat collector panels mounted on a south facing roof or wall each with transparent cover to harness sunlight. Water circulates through channels or pipes inside each panel. The inside is usually painted black, because black surfaces readily absorb heat. The water is heated, then the hot water is pumped to a heat exchanger that extracts the heat for use within the house.

4. where solar power comes from As fuel reserves dwindle, and prices go up, alternative energy forms are becoming essential for economic stability and the health of the planet. The advantages to be had from harnessing the heat from the sun makes solar energy a viable alternative source. The sun generates heat from its core on a continuous basis. Millions of years must pass before the heat from the sun's core reaches its surface and then a mere eight minutes before it reaches Earth. Overall, the sun radiates more energy in one second than the total amount used by humans since the beginning of time. Not unlike the other stars in the galaxy, the sun is a gas globe, though enormous in comparison to the stars.

5. In order to be able to use solar energy, it first has to be gathered together. Solar collectors are designed to absorb the sun's light, turn it into heat, and trap it inside a container. Solar panel systems incorporate this process using photovoltaic panels made up of silicone and various materials. The effects of sunlight on these panels causes their silicon electrons to generate a magnetic current. This current is then sent to an inverter which is a device that converts this direct current (DC) into an alternating current (AC). Once solar heat is converted into an AC current, it can be put to practical use. solar power generated

6. ADVANTAGES OF SOLAR ENERY : Solar cells are long lasting sources of energy which can be used almost anywhere. They are particularly useful where there is no national grid and also where there are no people such as remote site water pumping or in space. Solar cells provide cost effective solutions to energy problems in places where there is no mains electricity. Solar cells are also totally silent and non-polluting. As they have no moving parts they require little maintenance and have a long lifetime. Compared to other renewable sources they also possess many advantages; wind and water power rely on turbines which are noisy, expensive and liable to breaking down. DISADVANTAGES : The main disadvantage of solar energy is the initial cost. Most types of solar cell require large areas of land to achieve average efficiency. Air pollution and weather can also have a large effect on the efficiency of the cells. The silicon used is also very expensive and the problem of nocturnal down times means solar cells can only ever generate during the daytime. Solar energy is currently thought to cost about twice as much as traditional sources (coal, oil etc). Obviously, as fossil fuel reserves become depleted, their cost will rise until a point is reached where solar cells become an economically viable source of energy. When this occurs, massive investment will be able to further increase their efficiency and lower their cost . advantages & disadvantages

7. USEFUL : We know today that there are multiple uses of solar energy. We use the solar energy every day in many different ways. When we hang laundry outside to dry in the sun, we are using the solar heat to do work, drying our clothes. Plants use the solar light to make food. Animals eat plants for food. And as we learned, decaying plants hundreds of millions of years ago produced the coal, oil and natural gas that we use today Solar eneRgy moSt/leAst useFul LEAST USFUL ;Solar-panel manufacturers dumping toxic waste in China Solar panels may look bright and shiny, but they have a dark underbelly: production of polysilicon for panels gives off a highly toxic by-product called silicon tetrachloride. In China, where factories are rushing to alleviate a polysilicon shortage that’s cramping the global solar-panel industry, the bubbly white liquid is often just dumped in nearby villages. “The land where you dump or bury [silicon tetrachloride] will be infertile. No grass or trees will grow in the place,” says a material-sciences expert at Hebei Industrial University. “It is poisonous, it is polluting. Human beings can never touch it.” While silicon tetrachloride can be recycled — with significant investment cost, time, and energy consumption — many Chinese factories are cutting corners, and environmental agencies seem to largely be looking the other way. source

8. e & Jeong