Solar Energy: Solar Cells and Panels - UNSOLVED PRACTICE SET
Chapter: Sources of Energy | Topic: Solar Energy Solar Cells and Panels
SOLAR ENERGY: SOLAR CELLS AND PANELS - UNSOLVED PRACTICE SET
Topic: Solar Energy Solar Cells and Panels
Multiple Choice Questions
Q1. A solar cell (photovoltaic cell) converts:
- Electrical energy into light energy
- Solar (light) energy directly into electrical energy
- Heat energy into chemical energy
- Mechanical energy into solar energy
Q2. Solar cells are typically made from:
- Iron and steel
- Semiconductor materials such as silicon
- Pure copper wires
- Rubber and plastic
Q3. A 'solar panel' is:
- A single solar cell, much larger than usual
- An assembly of multiple solar cells connected together to produce a usable amount of electricity
- A device that stores solar energy as heat only
- A type of battery unrelated to sunlight
Q4. The output of a solar cell/panel is:
- AC (Alternating Current) directly suitable for home appliances
- DC (Direct Current), which often needs an inverter to convert to AC for home use
- Neither AC nor DC โ it produces heat only
- Mechanical motion
Q5. A major advantage of solar energy is:
- It works equally well day and night
- It produces electricity with no direct emissions during operation, using a resource (sunlight) that is freely available
- It requires constant fuel supply like coal
- It can only be used in space, not on Earth
Q6. A major limitation of solar panels is that their electricity output:
- Is constant throughout the day and night
- Depends on sunlight availability โ it is reduced on cloudy days and is zero at night without storage
- Increases at night
- Is unaffected by cloud cover or weather
Short Answer Questions
Q7. What is a solar cell? Briefly describe how it converts sunlight into electricity (you do not need to explain the detailed internal physics โ describe the overall process).
Q8. Distinguish between a solar cell, a solar panel, and a solar park. How do these three terms relate to each other in terms of scale?
Q9. Why is an inverter often needed alongside a rooftop solar panel installation in an Indian home?
Q10. List two advantages and two disadvantages/challenges of solar energy as an electricity source for households.
Q11. What is meant by a 'grid-connected' solar system versus an 'off-grid' (standalone) solar system? Give one example situation where each type would be used in India.
Q12. Explain why the orientation and tilt angle of solar panels (e.g., facing south in the Northern Hemisphere, at a certain angle) matters for their efficiency.
Long Answer Questions
Q13. Describe solar energy harnessing through solar cells and panels in detail. Your answer must cover:
(a) the basic working principle of a solar (photovoltaic) cell โ converting light directly to electricity,
(b) why semiconductor materials like silicon are used,
(c) how individual cells are combined into panels and arrays to scale up power output,
(d) the role of an inverter and battery storage in a complete solar power system, and
(e) two factors that affect the efficiency/output of a solar panel (e.g., sunlight intensity, angle, temperature, cleanliness).
Q14. A school in Rajasthan installs rooftop solar panels to power its lights, fans, and computer lab.
(a) Explain the complete system needed: panels, inverter, and possibly batteries โ describe the role of each.
(b) During school hours (daytime), how does the solar system supply electricity to the school's appliances?
(c) What happens on a cloudy day, or after sunset, if the school needs electricity but the panels are not producing enough?
(d) If the school's solar system produces MORE electricity than it needs on a sunny day, what could be done with the surplus (consider grid connection)?
(e) Discuss why solar energy is particularly well-suited for a state like Rajasthan, which receives abundant sunlight most of the year.
Q15. Compare solar energy with wind energy as renewable sources for electricity generation.
(a) Both depend on weather/environmental conditions (sunlight vs wind) โ compare the predictability of each on a daily and seasonal basis in a typical Indian location.
(b) Solar panels have no moving parts, while wind turbines have large rotating blades โ discuss how this difference might affect maintenance requirements and noise levels.
(c) Both can be installed at different scales (a single rooftop panel vs a large solar park; a single small turbine vs a large wind farm) โ discuss this flexibility for solar vs wind.
(d) India has ambitious targets for both solar and wind energy capacity โ why might a country want to invest in BOTH rather than choosing just one?
Numerical / Application-Based Problems
Q16. A solar panel has a rated power output of 300 W under standard test conditions (full, direct sunlight). On an average sunny day, it receives the equivalent of 5 'peak sun hours' (i.e., it effectively produces its rated power for about 5 hours' worth of energy, even though actual sunlight hours are longer but less intense at other times).
(a) Calculate the energy produced by this single panel in one day (in Wh, then convert to kWh).
(b) If a household installs 10 such panels, calculate the total daily energy production (in kWh).
(c) If the household's daily electricity consumption is 12 kWh, is the 10-panel system sufficient to meet their needs on an average sunny day? By how much (surplus or deficit)?
Q17. A solar water heater (a related but different technology โ converts sunlight directly to heat, not electricity) raises the temperature of 100 litres of water by 30ยฐC using solar energy. (Specific heat capacity of water = 4200 J/kgยฐC; 1 litre of water has a mass of 1 kg.)
(a) Calculate the total heat energy gained by the water (Q = mcฮT).
(b) If the solar collector receives solar energy at a rate equivalent to 800 W, and operates with 60% efficiency in transferring this to the water, calculate the useful heat energy delivered per hour (in Joules).
(c) Using your answers from (a) and (b), estimate how many hours of sunlight would be needed to heat the 100 litres of water by 30ยฐC.
Q18. A solar park is being planned with a total rated capacity of 50 MW (using many solar panels). The location receives an average of 6 peak sun hours per day.
(a) Calculate the total daily energy production (in MWh) at rated capacity for 6 hours.
(b) Convert this to kWh.
(c) If an average Indian household consumes 4 kWh per day, how many households could this solar park's daily output supply?
(d) If the park operates this way for 300 days a year (accounting for some cloudy/rainy days with reduced output), estimate the total annual energy production (in MWh) for those 300 days.