Solar Cell MCQ Quiz - Objective Question with Answer for Solar Cell - Download Free PDF

Explanation:

Maximum Power from a Solar Cell

To obtain maximum power from a solar cell, it must operate at its maximum power point (MPP), which is the specific point on its V-I (Voltage-Current) characteristics curve where the product of voltage (V) and current (I) is maximized. This ensures the solar cell delivers the highest possible power to the load.

The knee of the V-I characteristics curve is the region where the solar cell operates at its maximum power point (MPP). At this point, the voltage and current values are optimized to deliver maximum power, which is calculated as:

P = V × I

Here:

• P: Power output (in watts)
• V: Voltage (in volts)
• I: Current (in amperes)

The knee is a critical point because it represents the balance between voltage and current. Operating the solar cell at this point ensures the highest efficiency of energy conversion. Solar inverters and maximum power point trackers (MPPTs) are commonly used to identify and maintain operation at this knee point, adjusting the load resistance dynamically to maximize power output.

Importance of the Knee Point:

• Ensures the solar cell operates at its highest efficiency.
• Prevents the solar cell from operating in regions of lower power output on the V-I curve.
• Optimizes the utilization of available solar energy.

 Additional Information

• Environmental factors such as temperature, irradiance, and shading can affect the location of the knee point on the V-I characteristics curve. Advanced MPPT algorithms are designed to adapt to these changes in real-time.
• The knee point is typically located near the middle of the curve, between the flat portion (high current, low voltage) and the falling portion (high voltage, low current).

The correct answer is Semiconductors.

Important Points 

• Solar cells are made up of Semiconductors.
• Two kinds of semiconductors, called p-type and n-type silicon, make up a solar cell.
• The p-type silicon is created by the addition of atoms, such as boron or gallium, which have one fewer electron than silicon in their outer energy level.
• Since boron has one fewer electron than is needed, an electron vacancy or "hole" is produced to form bonds with the surrounding silicon atoms.
• A solar cell consists of a p-type silicon layer mounted next to an n-type silicon layer.

Key Points 

• An electrical insulator is a substance through which the electron does not flow freely or the isolator atom has closely bound electrons whose internal electrical charges do not flow freely, under the control of an electric field, very little electrical current can flow through it.
• A superconductor is a surface that gets cooler than a "critical temperature" conducts electricity without resistance.
• Conductors are the structures or objects that cause electricity to pass through them.

The correct answer is it has no moving parts.Key Points

• Solar cells are solid-state devices that convert sunlight directly into electricity, without the need for any mechanical or moving parts.
• This makes them highly reliable and durable, with very little maintenance required.
• The absence of moving parts also means that solar cells operate silently and without any emissions or pollution, making them a clean and sustainable source of energy.
• In contrast, options 1, 2, and 3 are all incorrect because they describe features that are not related to the functioning of a solar cell.
• Oscillatory motion, metal in the outer area, and moving parts are all characteristics that may apply to other types of devices, but not to solar cells.

Additional Information

• Solar cells are made of semiconductor materials such as silicon, which absorb photons of light and release electrons, creating a flow of electricity.
  • This process is called the photovoltaic effect, and it is the basis of solar power generation.
• Solar cells can be used in a wide range of applications, from small electronic devices like calculators and watches to large-scale power plants that supply electricity to homes and businesses.
• One of the challenges of solar power is that it is intermittent, meaning that it depends on the availability of sunlight.
  • To overcome this, solar systems often include energy storage devices like batteries or capacitors, which can store excess energy and release it when needed.
• Solar power is a rapidly growing industry, with increasing investment and innovation in both technology and business models.
  • As the cost of solar cells continues to decrease and the efficiency and reliability of solar systems improve, solar power is becoming an increasingly attractive option for meeting the world's energy needs.

Explanation:

• Solar cells, also known as photovoltaic cells, are devices that convert light energy directly into electrical energy through the photovoltaic effect.
• The most commonly used material for making solar cells is silicon.
• This is because silicon has several properties that make it ideal for this purpose, including its abundance, stability, and suitable electronic properties.
• Silicon is the primary material used in the majority of solar cells. It is a semiconductor, which means it can conduct electricity under certain conditions. Silicon solar cells can be classified into three main types:

• Monocrystalline Silicon: These cells are made from a single, continuous crystal structure. They are the most efficient type of silicon solar cells, with efficiency rates typically between 15-20%. However, they are also the most expensive due to the complex manufacturing process.
• Polycrystalline Silicon: These cells are made from silicon crystals that are melted together. They are less efficient than monocrystalline cells, with efficiency rates around 13-16%, but they are cheaper to produce.
• Amorphous Silicon: These cells are made from non-crystalline silicon and are often used in thin-film solar cells. They have lower efficiency rates, typically around 6-10%, but can be produced at a lower cost and are flexible.

The correct answer is Semiconductors.

Important Points 

• Solar cells are made up of Semiconductors.
• Two kinds of semiconductors, called p-type and n-type silicon, make up a solar cell.
• The p-type silicon is created by the addition of atoms, such as boron or gallium, which have one fewer electron than silicon in their outer energy level.
• Since boron has one fewer electron than is needed, an electron vacancy or "hole" is produced to form bonds with the surrounding silicon atoms.
• A solar cell consists of a p-type silicon layer mounted next to an n-type silicon layer.

Key Points 

• An electrical insulator is a substance through which the electron does not flow freely or the isolator atom has closely bound electrons whose internal electrical charges do not flow freely, under the control of an electric field, very little electrical current can flow through it.
• A superconductor is a surface that gets cooler than a "critical temperature" conducts electricity without resistance.
• Conductors are the structures or objects that cause electricity to pass through them.

Solar Array:

• Combining several solar cells in a series of parallel creates an array.
• The size of your solar array depends on the position of the roof and the energy requirement.
• A solar array can be used for solar heating, electrical power generation, lighting of spaces, etc
• For maximum current rating, the solar array is grouped in parallel.
• For maximum voltage rating, the solar array is grouped into series.

The correct answer is it has no moving parts.Key Points

• Solar cells are solid-state devices that convert sunlight directly into electricity, without the need for any mechanical or moving parts.
• This makes them highly reliable and durable, with very little maintenance required.
• The absence of moving parts also means that solar cells operate silently and without any emissions or pollution, making them a clean and sustainable source of energy.
• In contrast, options 1, 2, and 3 are all incorrect because they describe features that are not related to the functioning of a solar cell.
• Oscillatory motion, metal in the outer area, and moving parts are all characteristics that may apply to other types of devices, but not to solar cells.

Additional Information

• Solar cells are made of semiconductor materials such as silicon, which absorb photons of light and release electrons, creating a flow of electricity.
  • This process is called the photovoltaic effect, and it is the basis of solar power generation.
• Solar cells can be used in a wide range of applications, from small electronic devices like calculators and watches to large-scale power plants that supply electricity to homes and businesses.
• One of the challenges of solar power is that it is intermittent, meaning that it depends on the availability of sunlight.
  • To overcome this, solar systems often include energy storage devices like batteries or capacitors, which can store excess energy and release it when needed.
• Solar power is a rapidly growing industry, with increasing investment and innovation in both technology and business models.
  • As the cost of solar cells continues to decrease and the efficiency and reliability of solar systems improve, solar power is becoming an increasingly attractive option for meeting the world's energy needs.

The correct answer is Silicon.

Key Points

• Solar panels are usually made from a few key components: silicon, metal, and glass.
  • Standard panels are either made from monocrystalline or polycrystalline silicon.
  • Silicon is, by far, the most common material used in solar cells, representing approximately 90% of the modules sold today.
  • It is also the second most abundant material on Earth (after oxygen) and the most common semiconductor used in computer chips.
  • Crystalline silicon cells are made of silicon atoms connected to one another to form a crystal lattice.
  • This lattice provides an organized structure that makes conversion of light into electricity more efficient.

Concept:

The open-circuit voltage for a solar cell is given as:

\({{\rm{V}}_{{\rm{oc}}}} = {\rm{η }}~{{\rm{V}}_{\rm{T}}}\ln \left[ {1 + \frac{{{{\rm{I}}_{{\rm{s}}.{\rm{c}}}}}}{{{{\rm{I}}_0}}}} \right]\)

V_T = Thermal voltage

I_sc = Short circuit current

I₀ = Reverse saturation current

Calculation:

Given I_sc = 20 mA, V_oc = 0.65 volt V_T = 26 mV

Here η = 1, i.e.

\({{\rm{V}}_{{\rm{oc}}}} =0.026\ln \left( {1 + \frac{{20{\rm{mA}}}}{{{{\rm{I}}_0}}}} \right)\)

\(0.65 = 0.026\ln \left( {1 + \frac{{20{\rm{mA}}}}{{{{\rm{I}}_0}}}} \right)\)

\({{\rm{I}}_0} = \frac{{20{\rm{mA}}}}{{{{\rm{e}}^{\left( {0.65/0.026} \right)}} - 1}} \)

\(I_0= \frac{{20 \times {{10}^{ - 3}}}}{{7.2 \times {{10}^{10}}}} = 2.77 \times {10^{ - 13}}{\rm{Amp}} \)

Since I_sc ∝  Intensity

So, at 0.2 sun intensity, I_sc will be:

I_s.c = 0.2 × 20 mA = 4 mA

\({{\rm{V}}_{{\rm{oc}}}} = {\rm{η }}{{\rm{V}}_{\rm{T}}}\ln \left[ {1 + \frac{{4{\rm{mA}}}}{{2.77 \times {{10}^{ - 13}}}}} \right]\)

\(\\ {{\rm{V}}_{{\rm{oc}}}} = 0.026\ln \left[ {1 + \frac{{4{\rm{mA}}}}{{2.77 \times {{10}^{ - 13}}}}} \right] \)

\(V_{oc}= 0.608{\rm{\;volt}} \)

Explanation:

PN Junction Diode:

A diode is a two-terminal electronic component that conducts current primarily in one direction; it has low resistance in one direction, and high resistance in the other.

• A solar cell also converts light energy into electrical energy. It's basically a large-area photodiode.

Additional Information Diode under Forward Biasing:

When the diode is forward-biased and the applied voltage is increased from zero, at the initial level no current is flow.

It is because the external voltage is being opposed by the internal barrier voltage VB whose value is 0.7 V for Si and 0.3 V for Ge due to the majority carriers in both regions (Electrons in N region and Holes in P region).

As soon as VB is neutralized, the current through the diode increases rapidly with increasing applied battery voltage.

Reverse Biasing:

​In reversed bias, the negative region is connected to the positive terminal of the battery and the positive region is connected to the negative terminal. The reverse potential increases the strength of the potential barrier. The potential barrier resists the flow of charge carrier across the junction. It creates a high resistive path in which no current flows through the circuit.

Triodes:

• Vacuum triodes were used for amplification purpose before the discovery of transistors
• A triode is a vacuum tube with three electrodes which are a cathode, Anode, and a control grid
• These are used for Low-frequency operation

By applying a negative or positive voltage across control grid, the electron flow through the vacuum tube can be controlled.

• Solar cells, also called; photovoltaic cells, are the building blocks of solar panels
• Solar cells are made of semiconductor materials like silicon that produce a "photoelectric effect" when exposed to sunlight
• The photoelectric effect occurs when sunlight knocks electrons loose from their atoms
• The electrons then travel along a circuit built into the solar cell, creating a current of electricity
• The electricity can then be used immediately or stored in batteries

Solar cell:

• Solar photovoltaic (PV) systems convert solar energy directly into electrical energy.
• The basic conversion device used is known as a solar photovoltaic cell or solar cell.
• A solar cell is basically an electrical current source, driven by a flux of radiation as the current output energy is dependent on solar radiation.

• ​ The use of bypass diodes allows a series (called a string) of connected cells or panels to continue supplying power at a reduced voltage rather than no power at all.
• Bypas s diodes are connected in reverse bias between solar cells (or panel) positive and negative output terminals and have no effect on its output. 
• The bypass diodes’ function is to eliminate the hot-spot phenomena which can damage the PV cells and even cause a fire if the light hitting the surface of the PV cells in a module is not uniform. 
• Thus it enables the PV modules to operate with high reliability throughout their lifetime.

Solar Cells: 

• Solar cells convert the sun's energy into electricity.
• Solar cells are made of semiconductor materials like silicon, cadmium telluride, and copper indium gallium selenide.
• The working principle of solar cells is based on the photovoltaic effect.
• The photovoltaic effect is the production of electricity by a material when it is exposed to the light. 
• The common single-junction silicon solar cell can produce a maximum open-circuit voltage of approximately 0.5 - 0.6 V