30 Questions
What is converted into heat instead of electrical energy in a solar cell?
Excess energy generated
Which charge carriers migrate from the negative to positive side in the space charge region of a solar cell?
Holes
What cross-sectional area should the cable between the module and the battery have to ensure voltage loss does not exceed 3% for a 12-volt system?
0.35 mm2
How is the efficiency of a solar cell calculated?
By dividing the electric power by the total incident radiation intensity
What are the applications of solar photovoltaic systems listed in the text?
Lighting for farm houses, farm-to-market road, crop irrigation, and poultry incubators and hatchers
What happens to the open-circuit voltage of a solar cell as the temperature increases at constant radiation intensity?
It decreases
If a solar-powered pump requires 15 hp with a safety factor of 1.6, what is the total power required for the system?
23.4 kW
How many strings are needed to deliver the power required by the 800-volt inverter?
4 strings
How many modules are required for the solar-powered pump with module specifications of Wp – 310 watts, Isc – 8.84 Amp, Voc – 45.7 volts?
8 modules
Which material has the highest theoretical efficiency among the options given for solar cell materials?
GaAs
If a solar array needs to deliver power to a pump using an 800-volt inverter, how many modules per string are required for the array?
30 modules per string
Which of the following statements about the influence of radiation intensity on a solar cell is true?
The power output increases directly proportional to radiation intensity
What is the typical rating of solar radiation on a sunny day?
1 kW/m²
What is a solar battery rated in terms of?
Ampere-hour
Which of these devices generates electricity from sunlight?
Photovoltaic
What is the ampere-hour capacity of the battery needed for a 12V, 73.6 Wh solar panel system?
6.13 Ah
Which component of a solar electric system converts sunlight to electricity?
All of the above
Which factor affects solar radiation?
All of the above
What is the main advantage of using a solar cell module at low radiation intensity levels?
It can utilize the power output more efficiently.
What is the approximate weight of a solar cell module with 36 solar cells?
4 kg
What is the purpose of a charge regulator in a photovoltaic system?
To regulate the charging of the battery from the solar module.
What type of solar module material has the best efficiency in utilizing sunlight?
Mono Crystalline Silicon
If a solar-operated pump requires 74 volts, and each panel has a rating of 12 volts, how many panels are needed in series connection?
6 panels
What is the significance of the glass cover in a solar module?
It protects the solar cells from environmental factors.
What is one of the key steps mentioned to estimate the total load for a PV system?
Computing the total load and normalizing the load profile
Why is it important to select the appropriate array tilt for a PV system?
To optimize solar radiation capture at the proposed site
In estimating the array size in peak ampere, what formula is used in the provided text?
Array Size = Sum of Electrical Load for 2 worst months / Sum of Insolation for the same months
Why is it necessary to compute the battery storage requirement for a PV system?
To account for monthly deficit amounts
Which step involves selecting two adjacent months with the highest load-to-insolation ratio?
Estimating the array size in peak ampere
What is assumed when computing the total load and normalizing the load profile for a PV system?
Assume 90% current efficiency for the battery
Study Notes
Solar Cells and Photovoltaic Systems
- Solar cells convert sunlight into electrical energy through the separation of charge carriers (holes and electrons) in the presence of an electric field.
- The efficiency of a solar cell is determined by dividing the electric power output by the total incident radiation intensity.
- Theoretical and experimental efficiencies of various solar cell materials are:
- Si (mono crystalline): 22% (theoretical), 16% (experimental)
- Cu2CdS: 18% (theoretical), 7% (experimental)
- GaAs: 26% (theoretical), 21% (experimental)
- CdTe: 25% (theoretical), 6% (experimental)
Influence of Operating Temperature and Radiation Intensity
- Increasing temperature decreases the open circuit voltage, but has little effect on the short-circuit current.
- Power output decreases as temperature increases.
- Power output increases with radiation intensity.
Applications of Solar Photovoltaic Systems
- Lighting for farm houses, farm-to-market roads, and farm buildings
- Crop irrigation (non-pressurized and pressurized systems)
- Poultry incubators and hatchers
Solar Panel Systems and Modules
- A solar panel system consists of a solar module, battery, charge regulator, lamp, radios, and cables.
- Solar modules are arrays of solar cells interconnected and encapsulated behind a glass cover.
- The stronger the light on the cells and the larger the cell surface, the more electricity is generated.
- Characteristics of a solar cell module:
- Panel dimension: 560mm x 480mm x 13mm
- Weight: 4 kg
- Short circuit current: 1150 mA
- Open circuit voltage: 20.8 V
- Output current and power: 1010 mA and 15.9 W, respectively
Solar Module Materials
- Mono Crystalline Silicon: has the best efficiency (14%), but is more expensive than multi-crystalline silicon.
Designing a Solar Photovoltaic System
- Steps to design a solar photovoltaic system:
- Estimate the average daytime and night time current requirements.
- Compute the total load and normalize the load profile.
- Select the appropriate array tilt based on the location of the proposed PV site.
- Determine the insolation for the location and tilt angle.
- Compute the load-to-insolation ratio for each month.
- Estimate the array size in peak ampere for the two worst conditions.
- Compute the battery storage requirement.
Learn about the operational principle of a solar cell and how electric fields cause charge carriers to move, generating voltage and electric current. Explore the efficiency of solar cells and how excess energy is dissipated as heat. Test your knowledge on solar cell functionality!
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