Solar Photovoltaic

Solar photovoltaic (SPV) is the process of converting solar radiation (sunlight) into electricity using a device called solar cell. A solar cell is a semi-conducting device made of silicon or other materials, which, when exposed to sunlight, generates electricity. The magnitude of the electric current generated depends on the intensity of the solar radiation, exposed area of the solar cell, the type of material used in fabricating the solar cell, and ambient temperature. Solar cells are connected in series and parallel combinations to form modules that provide the required power.

Technology

The photovoltaic (pv) power technology uses semiconductor cells (wafers), generally several square centimeters in size. From the solid-state physics point of view, the cell is basically a large area p-n diode with the junction positioned close to the top surface. The cell converts the sunlight into direct current electricity. Numerous cells are assembled in a module to generate required power.

Cost

Because much of the current pv technology uses crystalline semiconductor material similar to integrated circuit chips, the production costs have been high.  The pv cell manufacturing process is energy intensive. Every square centimeter cell area consumes a few kWh before it faces the sun and produces the first kWh of energy. However, the manufacturing energy consumption is steadily declining with continuous implementation of new production processes. The present pv energy cost is still higher than the price the utility customers pay in most countries. For that reason, the pv applications have been limited to remote locations not connected to the utility lines.

Scope

With the declining prices, the market of new modules has been growing at more than a 15 percent annual rate during the last five years. The United States, the United Kingdom, Japan, China, India, and other countries have established new programs or have expanded the existing ones. It has been estimated that the potential pv market, with new programs coming in, could be as great as 1,600 MW by 2010.

Major advantages of the photovoltaic power are as follows:

• short lead time to design, install, and start up a new plant.
• highly modular, hence, the plant economy is not a strong function of size.
• power output matches very well with peak load demands.
• static structure, no moving parts, hence, no noise.
• high power capability per unit of weight.
• longer life with little maintenance because of no moving parts.
• highly mobile and portable because of light weight.