Solar energy is considered as renewable and an eco-friendly source of energy. It can be utilized by several ways; one of which is by the use of photovoltaic cells for its conversion into electricity. We heard a lot about solar cells and panels everyday but several questions pop up in our mind that what are these cells? How do they convert sunlight into electricity? And many other questions related to that. So, this is just a rough idea about the photovoltaic being used these days, so that you can all know about its function and working up to some extent and get familiar with it.
What are photovoltaic cells?
WATCH THIS VIDEO FIRST..
A solar cell, more aptly called a solar photo- voltaic cell converts the incident solar light energy into electrical energy in dc form. A solar cell is a small wafer of semi-conductor device, which has a light sensitive semi-conductor junction. When sun light falls on the semiconductor junction a potential difference is created between the two regions of the semiconductor junction thereby converting sun light into electrical energy. These days’ solar cells are made of semiconductor materials like silicon and gallium.
Earlier sun light was made to fall on layers of selenium element which was then crested to electrical energy. However the efficiency of selenium was only 0.7 percent. The solar cell could convert only 1 percent of sunlight to electrical energy. Due to the use of semiconductor like silicon, gallium and germanium, the efficiency of solar cells has increased to 15 percent. A modern selenium solar cell can convert 25 percent of solar energy into electricity. The multiple layer solar cells can convert both the visible and the infrared radiation into electricity.
A single solar cell can generate a power of only 0.3 W and for generating a high electric power a large number of solar cells are connected in series to obtain desired voltage. This group of cells arranged in definite patterns is called a solar panel. The electricity generated by the solar panel is stored in batteries and is utilized thereafter. They usually generate direct current and it is needed to be converted onto alternating current for use.
Merits of photovoltaic cells
- Solar cells provide clean, cheap, noiseless and safe energy.
- They do not possess any mobile parts so they rarely require any maintenance.
- Suitable for remote and inaccessible places where other fuels are scarce and costly.
- Suitable for portable or mobile load like, radio sets, cars, buses etc.
- Reliable and long life.
- Very low maintenance cost.
Demerits of photovoltaic cells
- Irregular supply of solar energy.
- Not economical for power plants of MW rating.
- Need for storage batteries.
- Do not generate power during cloudy season or rainy season.
- Very low efficiency (10-25 % only).
- Use of silver to connect the solar cells increases the cost of the solar panel.
Silicon photovoltaic cells are available in two types; Bulk types and Thin-film types whereas photovoltaic systems are classified principally into two types: grid connected or utility interactive systems and stand alone systems.