- Solar Cell Definition: A solar cell (also known as a photovoltaic cell) is defined as a device that converts light energy into electrical energy using the photovoltaic effect.
- Working Principle: Solar cells generate electricity when light creates electron-hole pairs, leading to a flow of current.
- Short Circuit Current: This is the highest current a solar cell can provide under optimal conditions without being damaged.
- Open Circuit Voltage: The voltage across the solar cell’s terminals when there is no load connected, typically around 0.5 to 0.6 volts.
- Efficiency: The efficiency of a solar cell is the ratio of its maximum electrical power output to the input solar radiation power, indicating how well it converts light to electricity.
Solar cell is the basic unit of solar energy generation system where electrical energy is extracted directly from light energy without any intermediate process. The working of a solar cell solely depends upon its photovoltaic effect hence a solar cell also known as photovoltaic cell. A solar cell is basically a semiconductor device. The solar cell produce electricity while light strikes on it and the voltage or potential difference established across the terminals of the cell is fixed to 0.5 volt and it is nearly independent of intensity of incident light whereas the current capacity of cell is nearly proportional to the intensity of incident light as well as the area that exposed to the light. Each of the solar cells has one positive and one negative terminal like all other type of battery cells. Typically a solar or photovoltaic cell has negative front contact and positive back contact. A semiconductor p-n junction is in the middle of these two contacts.
While sunlight falling on the cell the some photons of the light are absorbed by solar cell. Some of the absorbed photons will have energy greater than the energy gap between valence band and conduction band in the semiconductor crystal. Hence, one valence electron gets energy from one photon and becomes excited and jumps out from the bond and creates one electron-hole pair. These electrons and holes of e-h pairs are called light-generated electrons and holes. The light-generated electrons near the p-n junction are migrated to n-type side of the junction due to electrostatic force of the field across the junction. Similarly the light-generated holes created near the junction are migrated to p-type side of the junction due to same electrostatic force. In this way a potential difference is established between two sides of the cell and if these two sides are connected by an external circuit current will start flowing from positive to negative terminal of the solar cell. This was basic working principle of a solar cell now we will discuss about different parameters of a solar or photovoltaic cell upon which the rating of a solar panel depends. During choosing a particular solar cell for specific project it is essential to know the ratings of a solar panel. These parameters tell us how efficiently a solar cell can convert the light to electricity.
Short Circuit Current of Solar Cell
Short Circuit Current of Solar Cell: This is the maximum current a solar cell can deliver without damaging itself. It is measured by short-circuiting the cell’s terminals under optimal conditions. These conditions include the intensity of light and the angle of light incidence. Since current production also depends on the exposed surface area, it is better to express this as maximum current density, which is the ratio of short circuit current to the cell’s exposed surface area.
Where, Isc is short circuit current, Jsc maximum current density and A is the area of solar cell.
Open Circuit Voltage of Solar Cell
This is the voltage measured across the cell’s terminals when no load is connected. It depends on manufacturing techniques and temperature, but not significantly on light intensity or exposed surface area. The open circuit voltage of a solar cell is typically around 0.5 to 0.6 volts, denoted as Voc.
Maximum Power Point of Solar Cell
The maximum electrical power one solar cell can deliver at its standard test condition. If we draw the v-i characteristics of a solar cell maximum power will occur at the bend point of the characteristic curve. It is shown in the v-i characteristics of solar cell by Pm.
Current at Maximum Power Point
The current at which maximum power occurs. Current at Maximum Power Point is shown in the v-i characteristics of solar cell by Im.
Voltage at Maximum Power Point
The voltage at which maximum power occurs. Voltage at Maximum Power Point is shown in the v-i characteristics of solar cell by Vm.
Fill Factor of Solar Cell
The ratio between product of current and voltage at maximum power point to the product of short circuit current and open circuit voltage of the solar cell.
Efficiency of Solar Cell
This is defined as the ratio of the maximum electrical power output to the input radiation power, expressed as a percentage. On Earth, the radiation power is about 1000 watts per square meter. If the cell’s exposed surface area is A, the total radiation power on the cell will be 1000 A watts. Hence the efficiency of a solar cell may be expressed as
