Solar Cell construction

Silicon-based PV semiconductor solar cells have been used to demonstrate the most practical and reliable application of the photovoltaic effect. A simple, rugged semiconductor junction can be produced from single-crystal silicon. Low resistance contacts are added to tap the electrical energy produced when the cell is exposed to sunlight.

Approximately a DC voltage of 0.45 volts is generated across each cell regardless of the dimensions for this particular cell architecture. The DC current and thus the power available are strictly dependent on the cell area exposed to the sun and the absorption capability of the silicon wafer, which is located between the two contacts, as illustrated in Figure. It is important to mention that the higher the absorption capability of the semiconductor material, the higher the PV voltage will be across the cell terminals.

Higher voltage is possible by connecting the cells in series, while higher output power is possible by connecting the cells in parallel. Solar cells can be installed on glass-filled polyester substrate. The net cell output is the product of solar intensity (I = 100 mW/cm2) and the conversion efficiency of the device, which is typically now about 16 percent for a silicon cell. A solar module may contain several cells connected in series and parallel

 

Figure – Solar cell construction

Solar photovoltics

A solar cell (also called photovoltaic cell or photoelectric cell) is a solid state electrical device that converts the energy of light directly into electricity by the photovoltaic effect.

Assemblies of cells used to make solar modules which are used to capture energy from sunlight, are known as solar panels. The energy generated from these solar modules, referred to as solar power, is an example of solar energy.

Working Principle

Photovoltaics is the field of technology and research related to the practical application of photovoltaic cells in producing electricity from light, though it is often used specifically to refer to the generation of electricity from sunlight.

Cells are described as photovoltaic cells when the light source is not necessarily sunlight. These are used for detecting light or other electromagnetic radiation near the visible range, for example infrared detectors, or measurement of light intensity.

 

Figure – working principle of solar cell

The solar cell works in three steps:

1. Photons in sunlight hit the solar panel and are absorbed by semiconducting materials, such as silicon.
2. Electrons (negatively charged) are knocked loose from their atoms, allowing them to flow through the material to produce electricity. Due to the special composition of solar cells, the electrons are only allowed to move in a single direction.
3. An array of solar cells converts solar energy into a usable amount of direct current (DC) electricity.