Context:
An article in Hindu |Overcoming theoretical limits on solar cell capacity
Photovoltaic (Solar) Cells:
- An electrical device that uses the photovoltaic effect, physical and chemical phenomena, to convert light energy directly into electricity
- A device with electrical characteristics that change when exposed to light, such as current, voltage, or resistance
- Cells are made up of semiconducting materials like (doped) silicon.
- Individual solar cell devices are frequently used as the electrical components of photovoltaic modules, also known as solar panels.
- Major Types – Mono-crystalline Silicon Cell, Poly-crystalline Silicon Cell and Thin Film Silicon Cell
Photovoltaic – The study of conversion of light energy into electrical energy.
Shockley-Queisser limit isa theoretical concept that defines the maximum capacity of a solar cell to produce electricity
Working of Photovoltaic cells:
- Works on the same principle as that of the diode –
- Allows electric current to flow in a single direction and resist the reversal of the same current
- When sunlight interacts with a semiconductor, it excites electrons from the lower-energy valence band to the higher-energy conduction band
- This transition leaves behind a vacancy in the valence band called a hole
- A hole – A vacant site where an electron is supposed to be. Since it denotes the absence of an electron, a hole is also a place with positive charge
- It creates an electron-hole pair and these electron-hole pairs disrupt the neutrality of the conductor when the photon from external radiation hits the diode
- Then the electrons flowing through generates a DC current and the magnitude of this electromotive force generated is directly proportional to the intensity of the incident radiation
- In short, electron-hole pairs create the photocurrent
- Photocurrent – An electric current created as a result of radiation in the semiconductor
Related articles: Semiconductor Scheme, Light Emitting Diodes, International Solar Alliance
Source: The Hindu
Previous Year Question
With reference to technologies for solar power production, consider the following statements:
1. ‘Photovoltaics’ is a technology that generates electricity by direct conversion of light into electricity, while ‘Solar Thermal’ is a technology that utilizes the Sun’s rays to generate heat which is further used in the electricity generation process.
2. Photovoltaics generates Alternating Current (AC), while Solar Thermal generates Direct Current (DC).
3. India has a manufacturing base for Solar Thermal technology, but not for Photovoltaics.
Which of the statements given above is/are correct?
[UPSC Civil Services Exam – 2020 Prelims]
(a) 1 only
(b) 2 and 3 only
(c) 1, 2 and 3
(d) None
Answer: (a)
Explanation:
Statement 2 is not correct:
Solar energy can be converted directly into electrical energy (direct current, DC) by photovoltaic (PV) cells commonly called solar cells.
Statement 3 is not correct:
India has a manufacturing base for Solar Thermal technology as well as for Photovoltaics.
