Renewable Energy Source - Solar panels

Today natural energy sources are fading away. Therefore scientists are working hard on researches on various energy sources. Among them generating power using solar power has been showing promising results. There is a large quantity of energy that reaches the Earth as sunrays in each second. The animals and trees store a little part of the suns’ energy. The rest is wasted off. To obtain this energy and convert it to a useful energy type, we are using solar panels.

The basic principle of the solar panel can be identified with the knowledge of a p-n junction. The simple unit of a solar panel is the solar cell. This cell works as a p-n junction. When the cell is exposed to the sunlight a small current starts to flow through the cell. When there are a number of cells in the panel, the panel produces a acceptable voltage. The material that has used to make the cell has a large variety. Based on that the type of the solar panel is categorized.   

There are several types of solar panels that are available in the market.

Some of them are listed below

·         Thin Film solar cells

·         Single Crystal solar cells

·         Polycrystalline solar cells 

·         Al- Si Solar cells

Thin Film Solar Cells

As the name says the solar cell is a thin layer. It is made of a-Si: H and its alloys, CuInSe2 and its alloys or CdTe. Thin Si layers are used to increase the efficiency. These methods are the latest methods.

Single Crystal Solar Cells

This type solar cells are made by the wafers, which are sliced from a large crystal ingot, which is a very high pure silicon. These wafers are approximately .5 mm thick. The process is a very expensive on as the crystal has to heat up to around 1400 °C.

Polycrystalline Solar Cells

Thin wafers make these. A casting process made them. In this process molten silicon is poured into a mould and allowed to set. The resultant solid is sliced in to thin layers Even though the method is much cheaper polycrystalline wafers are not that much efficient as mono crystalline solar cells. That is mainly due to imperfections in the crystal structure resulting from the casting process.

Al-Si Solar Cells.

This type of solar cell can be applied as a film to low cost substrates such as glass or plastic There are many advantages of thin film cells including easier deposition and assembly, the ability to be deposited on inexpensive substrates or building materials. The ease of mass production, and the high suitability to large applications made this type of cells much more popular than the other types.

Other than that there are some other types of solar cells in the market. CdTe-based.Solar.Cells, which use Cu-doped contacts.  And the there is another one called CuIn Se based solar cells. New contacts must be tested and a method developed to rapidly characterize stability.

There are several factors that determine the efficiency of a solar cell. Out of them there is one main factor that influence the efficiency most. That is the amount of sun light that falls on to the solar panel. To determine this we have to consider several factors.

1. Weather conditions (cloud cover, fog etc.)
2. How high the sun is in the sky
3. The number of daylight hours

The clouds and fog like weather reduces the amount of the sunlight that falls on the solar cell. The power that produced by the panel is proportional to the amount of sunlight it gets. For an example a 50Wp solar panel would produce a power of 50 Watts in a 1000W/m2 sunshine and the production would be 25W in  500W/m2. that is why the solar panels are less popular in tropical countries.

In the countries where there is a significant difference in the seasons the height of the sun is a vital factor for the power production of the solar panel. In the summer where the sun is very high in the sky the rays reach the earth without much loss of its power. But in the winter where the sun is at the horizon allover the day ray has to pass more distance than in the summer thus dissipating more power to the atmosphere. There also may be shadows of trees and buildings etc.. . These conditions vary the efficiency of the solar panel.

For those who are living near the equator sees the sun each and every day. But in polar regions the number of hours that the sunlight falls on the ground are lesse4r. in such a situation the power productivity falls down.

Today in most of the countries solar panels are used as a power generating equipment. As a solution for the reducing energy sources it is promising to use solar power. In a solar panel the energy of the sunlight is directly converted in to elecric energy. The process is called photovoltaic effect. As other enrgy sources it doesn’t have much environmental effects. First solar cells were used ot provide power to satellites. Sooner the idea of solar power became a leading solution for the power crisis. Even though it is a high cost energy source it has been popular in third world countries. Even in rural areas where there is no access to the national grid solar panels are widely used to generate power to hose hold use. These systems often use batteries to store electricity. In counties like Australia solar panel power plants are used to supply electricity to the grid.