Solar Energy MCQ Quiz in मल्याळम - Objective Question with Answer for Solar Energy - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Concept:

Power delivered by the solar cells is given by:

Pmax = (F.F) × VOC. ISC

VOC = Open Circuit Voltage

ISC = Short Circuit Current and f

F.F. = Fill Factor

Calculation:

The fill factor of solar cells is:

\(\rm{ F. F = \frac{ maximum \ power \ obtained}{V_{oc} × I_{sc}}}\)

\(0.65 = \frac{65 × 10^{-3}}{V_{oc} × I_{sc}}\)

\(V_{oc} × I_{sc} = \frac{65 × 10^{-3}}{0.65} = 100 \ mW\)

∴ option 1 and 3 satisfy the result

i.e.

V_oc × I_sc = 40 mA × 2.5 V = 100 mV

Voc × Isc = 50 mA × 2 V = 100 mV

Explanation:

Pyranometers:

• A type of actinometer (an instrument for measuring the intensity of radiation, especially ultraviolet radiation) used to measure irradiance of solar energy or the total hemispherical solar radiation within the preferred location as well as the flux density of solar radiation.
• The range of solar radiation extends between 300 & 2800 nm.
• The SI units of irradiance are W/m² (watts /square meter).
• Usually, these are used in the fields of research like climatological & weather monitoring, but current attention is showing interest in pyranometers for solar energy worldwide.

Pyranometer Working Principle:

• The working principle of the pyranometer mainly depends on the difference in temperature measurement between two surfaces like dark and clear.
• The solar radiation can be absorbed by the black surface on the thermopile whereas the clear surface reproduces it, so less heat can be absorbed.
• The thermopile plays a key role in measuring the difference in temperature.
• The potential difference formed within the thermopile is due to the gradient of temperature between the two surfaces.
• These are used to measure the sum of solar radiation.
• But, the voltage which is generated from the thermopile is calculated with the help of a potentiometer. The information of radiation needs to be included through planimetry or an electronic integrator.

Pyranometer Design/Construction:

The pyrometer design or construction can be done using the following three components:

Thermopile:

• As the name implies, it uses a thermocouple used to notice dissimilarity in temperature between two surfaces. These are hot (labelled active) and cold (reference) accordingly. The labeled active surface is a black surface in a flat shape and it is exposed to the atmosphere. The reference surface depends on the difficulty of the pyranometer because it changes from a second control thermopile to the covering of the pyranometer itself.

Glass Dome:

• The glass dome in the pyrometer limits the response of spectral from 300 nm to 2800 nm from 180 degrees of view. It also protects the thermopile sensor from rain, wind, etc. This construction of the second dome gives extra radiation protection among the inner dome & sensor compared to a single dome because a second dome will reduce the instrument offset.

Occultation Disc:

• The occultation disc is mainly used to measure the radiation of the blocking beam & diffuse radiation from the panel surface.

Pyrheliometer:

• The pyrheliometer is one type of instrument, used to measure the direct beam of solar radiation at regular occurrence.
• It collimates the radiation to determine the beam intensity as a function of the incident angle.
• This instrument is used with a tracking mechanism to follow the sun continuously.
• It is responsive to wavelength bands that range from 280 nm to 3000 nm. These instruments are specially used for weather monitoring & climatological research purposes.

Pyrheliometer Construction & Working Principle:

• The external structure of the Pyrheliometer instrument looks like a telescope because it is a lengthy tube.
• By using this tube, we can spot the lens toward the sun to calculate the radiance.
• Here the lens can be pointed in the direction of the sun & the solar radiation will flow throughout the lens, after that tube & finally at the last part where the last part includes a black object at the bottom.
• The irradiance of solar enters into this device through a crystal quartz window and directly reaches a thermopile. So this energy can be changed from heat to an electrical signal that can be recorded.
• A calibration factor can be applied once changing the mV signal to a corresponding radiant energy flux, and it is calculated in W/m² (watts per square meter).
• This kind of information can be used to increase Insolation maps. It is a solar energy measurement, that is received on a specified surface region in a specified time to change around the Globe.
• The isolation factor for a specific area is very useful once setting up solar panels.

String inverters handle groups of solar panels (strings) individually. If one string is affected by shading, dirt, or mismatch (like different panel orientations or aging), it only impacts that specific string, not the entire system.

In contrast, central inverters connect many strings together, and a problem in one string (like shading or a faulty panel) can drag down the performance of the whole system.

Thus, string inverters reduce power loss from partial shading or panel mismatch, increasing overall system efficiency and performance.

String Inverter Technology

• A string inverter connects a “string” of solar panels (typically 8–30 panels) to a single inverter. Each string is treated as an independent unit.
• DC power from each string is sent to a dedicated string inverter, which converts it to AC power. Multiple string inverters are used across a large system.

Central Inverter Technology

• A central inverter collects DC power from many strings (hundreds of panels), combined through DC combiner boxes, and converts all the power to AC in one large unit.
• DC strings feed into combiner boxes. Combiner boxes route the power to a single large inverter (hundreds of kW to MW). AC power is sent to the grid or a distribution system.

Solar cell

• A solar cell is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect.
• The output of the solar cell is of the order of 1 W.
• A solar cell is a sandwich of n-type silicon and p-type silicon. It generates electricity by using sunlight to make electrons hop across the junction between the different layers of silicon.
• When sunlight shines on the cell, photons (light particles) bombard the upper surface.
• The photons (yellow blobs) carry their energy down through the cell.
• The photons give up their energy to electrons (green blobs) in the lower, p-type layer.
• The electrons use this energy to jump across the barrier into the upper, n-type layer and escape out into the circuit.
• Flowing around the circuit, the electrons make the lamp light up.

Concept:

LCD Modes:

1.) Reflective type cell:

If the one glass sheet used to sandwich the thin layer of a liquid crystal is deposited with transparent electrodes and the other with a reflective coating on their inside faces in a liquid crystal cell then it is known as a reflective type cell.

2.) Transmittive type cell:

If the two glass sheets used to sandwich the thin layer of a liquid crystal are deposited with a transparent electrode on their inside faces in a liquid crystal cell then it is known as a transmittive type cell.

3.) Transreflective type cell:

Transflective LCD displays have both transmissive and reflective characteristics. They contain an integrated backlight unit and a semi-transparent reflector or a reflector with a hole for each pixel.

The image shows a large collection of interconnected solar panels arranged in a grid to form a solar array.

Important terms related to Solar Plant:

• Solar Cell: The smallest unit that converts sunlight into electricity. Many solar cells make up a solar module.
• Solar Module (Panel): A single panel consisting of multiple solar cells connected.
• Solar Array: A group of multiple solar modules connected to generate higher power output. This is what is shown in the image.
• Battery Bank: A storage system for energy, but the image does not show batteries.

Explanation:

Solar Panels (Photovoltaic - PV) vs. Concentrating Solar Power (CSP):

Definition: Solar Panels (PV) and Concentrating Solar Power (CSP) are two prominent technologies used to harness solar energy. PV panels directly convert sunlight into electricity using semiconductor materials, while CSP systems use mirrors or lenses to concentrate sunlight onto a receiver to produce heat, which is then converted into electricity using a turbine or engine.

Correct Option Analysis:

The correct option is:

Option 2: They need costly batteries to store power for nighttime use.

This statement highlights one of the major challenges associated with Solar Panels (PV) compared to CSP systems. Solar Panels generate electricity during the daytime when sunlight is available, but they do not inherently have storage capabilities. To ensure a continuous power supply during nighttime or cloudy periods, it is necessary to pair PV systems with energy storage solutions, typically batteries.

While CSP systems often use thermal storage methods (e.g., molten salt) to store heat energy for later use, PV systems rely on batteries, which are expensive and can significantly increase the overall cost of the system. The integration of batteries into PV setups also presents challenges related to scalability, efficiency, and environmental concerns due to the mining and disposal of battery materials.

Detailed Explanation:

1. The Need for Energy Storage:

• Solar Panels (PV) produce electricity only when sunlight is available, meaning their output is intermittent and depends on the weather and time of day.
• To achieve a stable and reliable energy supply, PV systems often require batteries to store excess energy generated during the day for use during nighttime or cloudy periods.
• The cost of batteries, such as lithium-ion batteries, is a significant factor in the overall expense of a PV system. Additionally, battery lifespan and efficiency can impact the long-term viability of the system.

2. Cost Implications:

• Batteries are one of the most expensive components of a PV system. Their cost can rival or even exceed the cost of the solar panels themselves.
• The maintenance and replacement of batteries add to the operational costs, making PV systems less economically competitive compared to CSP in some cases.
• The environmental impact of battery production and disposal is another concern, as the extraction of materials like lithium and cobalt can cause ecological harm.

3. Comparison with CSP:

• CSP systems typically use thermal storage techniques, such as molten salt storage, which are more cost-effective and environmentally friendly compared to batteries.
• Thermal storage allows CSP systems to generate power even after sunset, providing a more consistent and reliable energy output.

4. Advances in Battery Technology:

• Research and development in battery technology, including solid-state batteries and flow batteries, aim to reduce costs and improve efficiency, which could make PV systems more competitive in the future.
• Despite these advancements, the current reliance on costly batteries remains a significant challenge for PV systems.

Conclusion:

Option 2 correctly identifies the major challenge of Solar Panels (PV) needing costly batteries for nighttime energy storage. This reliance on batteries increases the cost and complexity of PV systems compared to CSP systems, which often utilize more efficient and cost-effective thermal storage solutions.

Additional Information

Analysis of Other Options:

Option 1: They have lots of moving parts, making maintenance costly.

This statement is incorrect for Solar Panels (PV). PV systems have no moving parts, which is one of their advantages over CSP systems. CSP systems involve components like mirrors, tracking systems, and turbines, which require regular maintenance and have higher operational costs due to their mechanical complexity.

Option 3: They completely stop working on cloudy days.

This statement is misleading. While the efficiency of PV systems decreases on cloudy days due to reduced sunlight, they do not "completely stop working." Advanced PV panels can still generate some electricity under diffuse light conditions, although at a lower output. CSP systems, on the other hand, rely on direct sunlight for optimal performance and are more affected by cloudy weather.

Option 4: They need high-tech factories to be made.

This statement is partially correct but not unique to PV systems. Both PV and CSP technologies require specialized manufacturing facilities. PV panels involve semiconductor fabrication, which necessitates high-tech factories, but CSP systems also require precision engineering for mirrors, receivers, and tracking systems. Therefore, this challenge is not exclusive to PV systems.

Conclusion:

While all the options highlight challenges related to solar technologies, Option 2 accurately identifies the significant issue of costly batteries for energy storage in PV systems, making it the correct choice. Understanding these challenges is essential for selecting the appropriate solar technology based on specific needs and conditions.

Efficiency of Fresnel Reflector in a Solar Concentrator System

Definition: A Fresnel reflector is a type of solar concentrator that uses a series of flat or slightly curved mirror strips to concentrate sunlight onto a specific target, such as a receiver tube or a photovoltaic cell. This system is widely used in solar thermal and photovoltaic applications to improve energy efficiency by concentrating sunlight.

Correct Option Analysis:

The correct option is:

Option 1: The number of mirror strips and their alignment accuracy.

The efficiency of a Fresnel reflector in a solar concentrator system is significantly influenced by the number of mirror strips and their alignment accuracy. This is because:

• Number of Mirror Strips: The more mirror strips a Fresnel reflector has, the higher the precision in concentrating sunlight onto the target. A larger number of strips allows for better division of the reflected sunlight and minimizes energy loss due to gaps or misalignment.
• Alignment Accuracy: The alignment of the mirror strips is critical for ensuring that the reflected sunlight is focused precisely on the target. Even a slight misalignment can result in a significant loss of concentrated sunlight, reducing the system's overall efficiency. Advanced tracking systems and precise calibration are often employed to maintain alignment accuracy.

In essence, the number of mirror strips determines the potential concentration capability of the system, while alignment accuracy ensures that this potential is effectively utilized. Both factors work together to maximize the efficiency of the Fresnel reflector in capturing and concentrating solar energy.

Working Principle:

In a Fresnel reflector system, sunlight is reflected by the mirror strips and directed towards a focal point or line. The concentration of sunlight at this focal point increases the thermal or photovoltaic energy output. The efficiency of this process depends on how well the sunlight is concentrated, which in turn relies on the design and alignment of the mirror strips.

Advantages:

• Cost-effective compared to parabolic concentrators due to simpler construction.
• Lightweight and easier to install and maintain.
• Can achieve high levels of concentration when properly aligned.

Disadvantages:

• Requires precise alignment and tracking systems to maintain efficiency.
• Prone to energy losses if the mirror strips are misaligned or if there are gaps between them.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 2: The temperature of the environment.

While the temperature of the environment can influence the overall performance of a solar concentrator system, its impact on the efficiency of the Fresnel reflector itself is minimal. Environmental temperature primarily affects the thermal losses in the receiver and the efficiency of the energy conversion process, not the reflector's ability to concentrate sunlight.

Option 3: The colour of the reflector material.

The colour of the reflector material is not a significant factor in the efficiency of a Fresnel reflector. What matters more is the reflectivity of the material. Highly reflective materials, regardless of their colour, are better at concentrating sunlight. Therefore, this option is incorrect.

Option 4: The wavelength of incident light.

The wavelength of incident light can affect the reflectivity of the mirror material to some extent, but this is a secondary consideration. Most Fresnel reflectors are designed to work efficiently across the spectrum of sunlight. The wavelength of light is not as critical as the number of mirror strips and their alignment accuracy in determining efficiency.

Conclusion:

The efficiency of a Fresnel reflector in a solar concentrator system is primarily determined by the number of mirror strips and their alignment accuracy. These factors directly influence the system's ability to concentrate sunlight onto the target, making them the most significant contributors to efficiency. While other factors like environmental temperature, reflector material properties, and incident light wavelength play a role, their impact is comparatively minor.

The correct answer is 6 to 7.

Key Points

• Rajasthan has a lot of solar energy potential.
• Rajasthan has a semi-arid climate, and the Thar Desert covers 66.66% of the state's total land area.
• With these climatic characteristics, it may receive 6-6.4 kwh/m² of solar radiation per day.
• This is the second-highest amount in the globe and around 300–325 sunny days annually.
• The western cities of Rajasthan often experience temperatures between 35 and 40 degrees, with summertime highs of above 45 degrees.
• Rajasthan has a solar energy availability of 6 to 7 kw/km².
• It has the capacity to produce 100000 MW of power year, albeit only 442.25 MW is currently being produced.

Additional Information

• Solar radiation intensity:
  • It is the density of solar radiation coming per unit area of the photoelectric module. 
  • Above the earth's atmosphere, solar radiation has an intensity of approximately 1380 watts per square meter (W/m²).