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PG Diploma Solar Semester one Paper 3 Exam Section B
- April 21, 2026
- Posted by: iisemumbai
- Category: Question bank Uncategorized
Solar PV Basics
Q1. Explain the working principle of a solar photovoltaic cell.
Answer:
A solar photovoltaic cell converts sunlight directly into DC electricity using the photovoltaic effect. When photons strike the semiconductor material, electrons are released and flow through an external circuit. This creates usable electric current. Silicon is commonly used.
Q2. What are the advantages of solar photovoltaic technology?
Answer:
Solar PV has no moving parts, low maintenance, and produces clean energy without pollution. It can be installed in small or large capacities. It reduces electricity bills and dependence on fossil fuels.
Q3. What are the limitations of solar energy?
Answer:
Solar energy depends on sunlight availability and weather conditions. Power generation reduces during cloudy days and stops at night. Initial installation cost can also be comparatively high.
Q4. Explain the difference between solar cell, module, panel, and array.
Answer:
A solar cell is the smallest unit producing electricity. Multiple cells form a module. One or more modules with mounting structure form a panel. Multiple panels connected together form an array.
Q5. Why is silicon widely used in solar cells?
Answer:
Silicon is a semiconductor material suitable for photovoltaic conversion. It is abundant, reliable, and has good electrical properties. It offers long life and acceptable efficiency for commercial solar panels.
Solar Modules
Q6. Describe the construction of a solar PV module.
Answer:
A solar PV module contains interconnected solar cells sealed between tempered glass and backsheet using EVA encapsulation. It has an aluminium frame and junction box. These parts protect the cells and provide structural strength.
Q7. What is the function of EVA in solar modules?
Answer:
EVA (Ethylene Vinyl Acetate) is used as an encapsulant in solar modules. It holds cells firmly in place and protects them from vibration, moisture, and environmental damage. It also allows light transmission.
Q8. What is the purpose of the backsheet in a module?
Answer:
The backsheet protects the rear side of the module from moisture, dust, and electrical leakage. It also provides insulation and increases module durability under outdoor conditions.
Q9. Explain the role of tempered glass in solar panels.
Answer:
Tempered glass is placed on the front side of solar modules. It protects cells from impact, dust, and weather while allowing sunlight to pass through efficiently. It improves module life and safety.
Q10. Why is an aluminium frame used in modules?
Answer:
The aluminium frame provides mechanical strength and supports installation on structures. It protects edges of the module and makes handling easier during transport and mounting.
Solar Specifications
Q11. What is Voc in a solar panel specification sheet?
Answer:
Voc means open circuit voltage. It is the maximum voltage available from a solar panel when no load is connected. It is important for string design and inverter compatibility.
Q12. What is Isc in solar panel data?
Answer:
Isc means short circuit current. It is the maximum current produced when panel terminals are shorted under standard test conditions. It is used for cable and protection design.
Q13. Explain Standard Test Conditions (STC).
Answer:
STC are laboratory conditions used to rate solar panels. They include irradiance of 1000 W/m², cell temperature of 25°C, and air mass 1.5. It provides a standard basis for comparing panels.
Q14. What is NOCT?
Answer:
NOCT means Normal Operating Cell Temperature. It reflects module performance under more realistic outdoor conditions such as 800 W/m² irradiance and ambient temperature. It helps estimate real-world output.
Q15. Why is a specification sheet important?
Answer:
A specification sheet provides electrical, thermal, mechanical, and warranty data of a panel. It helps designers choose suitable modules and configure safe, efficient solar systems.
Charge Controller
Q16. Explain the functions of a solar charge controller.
Answer:
A solar charge controller regulates voltage and current from the solar panel to the battery. It prevents overcharging and deep discharge. It improves battery life and system safety.
Q17. Why is a charge controller required in off-grid systems?
Answer:
Off-grid systems use batteries for storage. A charge controller ensures batteries charge safely and are not damaged by excessive voltage or over-discharge during use.
Q18. What happens if no charge controller is used?
Answer:
Without a charge controller, batteries may overcharge, overheat, or deeply discharge. This reduces battery life and can create unsafe operating conditions.
Q19. What is load control in charge controllers?
Answer:
Load control means the controller disconnects loads when battery voltage falls too low. This prevents excessive discharge and protects battery health.
Q20. How does a controller improve battery life?
Answer:
It maintains correct charging voltage, avoids overcharging, and prevents deep discharge. Proper charging cycles significantly increase battery service life.
Inverter
Q21. Why is an inverter required in solar systems?
Answer:
Solar panels generate DC electricity, but most appliances use AC supply. An inverter converts DC into AC and provides usable power for homes and businesses.
Q22. What are the main types of power converters?
Answer:
The main converters are AC to DC rectifiers, DC to DC converters, and DC to AC inverters. Each is used depending on system requirements.
Q23. What is a rectifier?
Answer:
A rectifier converts AC power into DC power. It is used in electronic devices and charging equipment where DC supply is required.
Q24. What is a DC/DC converter?
Answer:
A DC/DC converter changes one DC voltage level to another higher or lower level. It is commonly used inside inverters and electronic systems.
Q25. How does a grid inverter work?
Answer:
A grid inverter converts DC from solar panels into synchronized AC supply matching grid voltage and frequency. Excess energy can be exported to the utility grid.
Batteries
Q26. What is a battery?
Answer:
A battery is an electrochemical device that stores chemical energy and converts it into electrical energy when connected to a load. It is used for backup and storage.
Q27. Name common batteries used in solar systems.
Answer:
Lead-acid, tubular, lithium-ion, and LFP batteries are commonly used in solar systems. Selection depends on cost, backup requirement, and life cycle.
Q28. Explain lead-acid battery advantages.
Answer:
Lead-acid batteries are economical, widely available, and easy to maintain. They are commonly used in small off-grid systems and backup applications.
Q29. Explain lithium battery advantages.
Answer:
Lithium batteries have higher efficiency, faster charging, lighter weight, and longer cycle life. They require less maintenance than lead-acid batteries.
Q30. What is battery capacity?
Answer:
Battery capacity is the amount of charge a battery can store, commonly measured in ampere-hours (Ah). It indicates backup duration.
Battery Connections
Q31. Explain series connection of batteries.
Answer:
In series connection, positive of one battery is connected to negative of the next. Voltage adds while Ah capacity remains the same. It is used for higher system voltage.
Q32. Explain parallel connection of batteries.
Answer:
In parallel connection, all positive terminals and all negative terminals are connected together. Voltage remains same while Ah capacity increases. It gives longer backup time.
Q33. Why should mismatched batteries not be connected?
Answer:
Different capacity or chemistry batteries charge and discharge unevenly. This causes imbalance, reduced life, overheating, and poor system performance.
Q34. Why should batteries be fully charged before series connection?
Answer:
Fully charging batteries before series connection ensures equal voltage levels. This prevents imbalance and improves performance and life.
Q35. What happens if one battery fails in series string?
Answer:
A faulty battery reduces the total string voltage and may cause premature shutdown of equipment. It affects the whole bank performance.
Load Calculation
Q36. Why is load calculation important?
Answer:
Load calculation determines total power and daily energy consumption. It is the first step in selecting panels, inverter size, and battery bank.
Q37. What is an electrical load?
Answer:
An electrical load is any device that consumes electrical power and converts it into light, heat, motion, or other useful forms of energy.
Q38. What is continuous load?
Answer:
Continuous load is equipment that runs for long durations or 24 hours a day. Examples include refrigerators and certain industrial systems.
Q39. How is daily energy consumption calculated?
Answer:
Daily energy consumption is calculated by multiplying appliance power rating by hours of operation. Result is expressed in watt-hours or kWh.
Q40. What is the meaning of 1 kWh?
Answer:
1 kWh means using 1 kilowatt of power for one hour. It is equal to one unit of electricity in billing.
Electricity Bill Audit
Q41. What is electricity bill audit?
Answer:
Electricity bill audit means reviewing electricity usage, tariff, taxes, and demand charges to recommend the most suitable solar solution.
Q42. Why is bill audit useful before solar installation?
Answer:
It identifies consumption patterns, sanctioned load, and cost-saving opportunities. This helps optimize system size and financial returns.
Q43. What is sanctioned load?
Answer:
Sanctioned load is the maximum load approved by the electricity distribution company for a consumer connection.
Q44. What is contract demand?
Answer:
Contract demand is the agreed maximum demand in kW or kVA between utility and consumer, mainly for commercial or industrial users.
Q45. Explain HT and LT supply.
Answer:
HT means High Tension supply used for larger consumers. LT means Low Tension supply used for homes and small commercial loads.
Miscellaneous
Q46. What is a solar array?
Answer:
A solar array is a group of solar panels electrically connected to generate required power. It may be used for homes, commercial buildings, or utility plants.
Q47. What factors decide number of panels in an array?
Answer:
Important factors are panel wattage, voltage/current rating, daily energy requirement, and local sunshine conditions.
Q48. Why is maintenance required in PV systems?
Answer:
Maintenance includes cleaning, inspection, and fault checking. It improves performance, ensures safety, and extends equipment life.
Q49. How does dust affect solar modules?
Answer:
Dust blocks sunlight reaching the cells, reducing output power. Regular cleaning helps maintain expected generation.
Q50. Why is renewable energy important?
Answer:
Renewable energy reduces pollution, conserves fossil fuels, and supports sustainable development. It improves long-term energy security.