CEM Renewable Energy Systems 1 ā Questions and Answers
Question 1: What is the typical efficiency range of commercial silicon photovoltaic (PV) solar panels under standard test conditions?
- 5ā10%
- 15ā22% (Correct answer)
- 30ā40%
- 45ā55%
Correct answer: 15ā22%
Commercial silicon PV panels typically achieve 15ā22% efficiency under standard test conditions (STC) of 1,000 W/mĀ² and 25Ā°C.
Question 2: Wind turbine power output is proportional to which mathematical relationship with wind speed?
- Linear (speedĀ¹)
- Squared (speedĀ²)
- Cubic (speedĀ³) (Correct answer)
- Logarithmic (ln speed)
Correct answer: Cubic (speedĀ³)
Wind turbine power output is proportional to the cube of wind speed (P ā vĀ³), meaning doubling wind speed increases power output eightfold.
Question 3: What does 'capacity factor' mean for a renewable energy system?
- The maximum power output the system can produce
- The ratio of actual energy produced to the maximum possible energy output over a period (Correct answer)
- The percentage of time the system is online and not in maintenance
- The efficiency rating of the inverter under full load
Correct answer: The ratio of actual energy produced to the maximum possible energy output over a period
Capacity factor is the ratio of actual energy produced over a time period to the energy that would have been produced if the system operated at full rated capacity for the same period.
Question 4: What is net metering in the context of a grid-tied solar energy system?
- Measuring the net carbon emissions offset by solar panels
- Calculating the net installation cost after available incentives
- A billing arrangement where excess electricity exported to the grid earns credits on the customer's utility bill (Correct answer)
- The process of measuring cumulative solar panel performance degradation
Correct answer: A billing arrangement where excess electricity exported to the grid earns credits on the customer's utility bill
Net metering allows solar system owners to export surplus electricity to the utility grid and receive bill credits at the retail rate for that exported energy.
Question 5: Which renewable energy technology harnesses the Earth's internal heat to generate electricity or provide direct heating?
- Solar thermal concentrating
- Biomass combustion
- Tidal barrage
- Geothermal (Correct answer)
Correct answer: Geothermal
Geothermal energy extracts heat stored within the Earth, using steam or hot water from underground reservoirs to drive turbines or provide direct space and process heat.
Question 6: The federal Investment Tax Credit (ITC) in the United States provides a direct tax credit primarily for which technology?
- Energy-efficient commercial lighting upgrades
- Solar energy system installations (Correct answer)
- Plug-in electric vehicles
- Energy auditing and commissioning services
Correct answer: Solar energy system installations
The federal ITC provides a percentage-based tax credit calculated on the installed cost of solar PV, solar thermal, and other solar energy systems.
Question 7: Which unit is used to express solar irradiance, representing the instantaneous power of solar radiation striking a surface?
- Lumens per square meter (lm/mĀ²)
- Watts per square meter (W/mĀ²) (Correct answer)
- Kilowatt-hours per day (kWh/day)
- BTU per hour (BTU/hr)
Correct answer: Watts per square meter (W/mĀ²)
Solar irradiance is a power density measure expressed in watts per square meter (W/mĀ²); the standard test condition value used for panel ratings is 1,000 W/mĀ².
CEM Renewable Energy Systems 1
What is the typical efficiency range of commercial silicon photovoltaic (PV) solar panels under standard test conditions?