Solar Photovoltaic
Understanding Photovoltaic Cells and Modules
The words ‘photo’ and ‘voltaic’ literally translate to ‘light’ and ‘current’ respectively. Sunlight is made of little packets of energy called ‘photons’ and the photovoltaic (PV) cells of a solar module are made of semiconductor materials Figure 1.
Thus, a solar cell is an electronic device which directly converts sunlight into electricity. Light shining on the solar cell produces both a current and a voltage to generate electric power. When the photons strike a typical photovoltaic cell, the energy from the light is absorbed by the semiconductor material in the solar cell and this releases electrons in the process. It is this flow of electrons that creates electric current.
Hence, the process of converting sunlight to electricity usually involves two basic stages. The first stage requires a material in which the absorption of light raises an electron to a higher energy state. In the second stage, there is a movement of the higher energy electron from the solar cell into an external circuit (e.g. the load). The electron then dissipates its energy in the external circuit and returns to the solar cell. This creates a complete path for electron movement and by extension current flow.
A variety of materials and processes can potentially satisfy the requirements for photovoltaic energy conversion, but in practice nearly all photovoltaic energy conversion uses semiconductor materials in the form of a p-n junction. Take Solar Power Quiz
1 What physical effect is responsible for solar cells generating electricity?
A) Photoelectric effect
B) Photovoltaic effect
C) Electromagnetic induction
2 When solar cells are connected in series, what increases?
A) Voltage
B) Current
C) Power loss
3 In a typical 60-cell solar module, if each cell produces 0.6V, what’s the approximate module voltage?
A) 18V
B) 36V
C) 60V
4 Why are modules made of many small cells instead of one giant cell?
A) Cost efficiency & reliability
B) Better shade tolerance
C) Both A and B
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