Principle of operation of solar Energy,all that you need to know

Principle of operation of solar Energy,all that you need to know

Solar energy is available in abundance in most parts of the world. The amount of solar energy incident on the earth’s surface is approximately1.5 x 1018 kWh/year, which is about 10,000 times the current annual energy consumption of the entire world.

The density of power radiated from the sun (referred to as solar energy constant) is 1.373 kW/m2.
Solar cell is a device which converts photons in Solar rays to direct-current (DC) and voltage. The associated technology is called Solar Photovoltaic (SPV). A typical silicon PV cell is a thin wafer consisting of a very thin layer of phosphorous-doped (N-type) silicon on top of a thicker layer of
boron-doped (P-type) silicon.
An electrical field is created near the top surface of the cell where these two materials are in contact (the P-N junction).
When the sunlight hits the semiconductor surface, an electron springs up and is attracted towards the
N-type semiconductor material. This will cause more negatives in the n-type and more positives in the P-type semiconductors, generating a higher flow of electricity. This is known as Photovoltaic effect.
The amount of current generated by a PV cell depends on its efficiency, its size (surface area) and the intensity of sunlight striking the surface. For example, under peak sunlight conditions a typical commercial PV cell with a surface area of about 25 square inches will produce about 2 watts peak power.

Advantages and Limitations of Solar Energy
Renewable energy sources in general, and Solar Energy source in particular, has the potential to provide energy services with zero or almost zero emission. The solar energy is abundant and no other source in renewable energy is like solar energy. Every technology has its own advantages and
disadvantages. As the solar insolation and atmospheric conditions vary significantly from place to place, efficiency of solar energy also differs accordingly.

Advantages
>> It is an abundant Renewable Energy.
This technology is Omnipresent and it can be captured for conversion on a daily basis.
>>It is a Non-polluting technology, which means that it does not release green house gases.
>>It is a Noiseless technology as there are no moving parts involved in energy generation.
>>This technology requires Low-maintenance because of lack of moving parts.
>>It can be installed on modular basis and expanded over a period of time.
>>Most viable alternative for providing electricity in remote rural areas as it can be installedwhere the energy demand is high and can be expanded on modular basis.

Limitations
>>As the technology is in an evolving stage, the efficiency levels of conversion from light to electricity is in the range of 10 to 17%, depending on the technology used.
>>The initial investment cost of this technology is high.
>>At present the technology is basically
surviving because of subsidy schemes available by the government.
>>Solar energy is available only during daytime. Most load profiles indicate peak load in the
>>evening/night time,this necessitates expensive storage devices like battery, which need to be replaced every 3 to 5 years. Generally, the cost of the Battery is 30 to 40% of the system cost.
>>As the efficiency levels are low, the space required is relatively high,For instance, with the existing levels of technologies, the land required for putting up a 1 MW solar PV power plant is between 6 to 9 acres. However, research is going on to increase the efficiency levels.
>> the Solar energy is heavily dependent on atmospheric conditions.
>> Solar insolation varies from location to location, so there are certain geographic limitations in generating solar power.
>> With the existing module and inverter manufacturing technologies, it may not be worthwhile in terms of costs to deploy solar energy for certain loads which require very high starting power (e.g. air conditioners).

Solar Receiver Technologies
The types of receivers used for collecting solar energy are classified as follows:
>>Flat Plate Arrays
>>Tracking Arrays
>>Concentrator Arrays

Solar Photovoltaic Technologies
The heart of the Solar energy generation system is the Solar cell. It consists of three major elements,
namely:
>>The semiconductor material which absorbs light and converts it into electron-hole pairs.
>>The junction formed within the semiconductor, which separates the photo-generated carriers (electrons and holes)
>>The contacts on the front and back of the cell that allow the current to flow to the external

Two main streams of technologies have been evolved for the manufacture of Solar Cells/Modules namely:
>>Flat plate Technology
>>Concentrated Technology

The Flat Plate Technology is further classified in two ways namely :Crystalline Technology and Thin Film Technology.

The Concentrated Photovoltaic Technology has been classified according to the
Type of cell and the Optical system.

Source:saealert