Certified Energy Auditor Certification Renewable Energy Systems 1 — Questions and Answers
Question 1: What is the 'capacity factor' of a renewable energy system?
- The ratio of actual energy output over a period to the maximum possible output at full rated capacity (Correct answer)
- The percentage of renewable energy in a building's total energy mix
- The efficiency rating of the equipment under standard test conditions
- The ratio of installed capacity to the peak demand of a facility
Correct answer: The ratio of actual energy output over a period to the maximum possible output at full rated capacity
Capacity factor is the ratio of actual energy produced to the maximum possible energy if the system operated at full rated capacity continuously over the same period.
Question 2: Which unit is used to measure solar irradiance?
- kWh/m²
- W/m² (Correct answer)
- BTU/hr·ft²
- lux
Correct answer: W/m²
Solar irradiance is the instantaneous power of solar radiation per unit area, expressed in watts per square meter (W/m²).
Question 3: What is the primary difference between photovoltaic (PV) and solar thermal systems?
- PV systems use mirrors to concentrate sunlight while solar thermal uses flat panels
- PV systems convert sunlight directly to electricity while solar thermal captures solar heat energy (Correct answer)
- PV systems require tracking mounts while solar thermal systems are always fixed
- PV systems work only during peak sunlight hours while solar thermal stores energy for night use
Correct answer: PV systems convert sunlight directly to electricity while solar thermal captures solar heat energy
Photovoltaic systems directly convert solar radiation to electricity via the photovoltaic effect, while solar thermal systems capture solar energy as heat for water or space heating applications.
Question 4: What are Standard Test Conditions (STC) for rating photovoltaic panels?
- 25°C cell temperature, 1000 W/m² irradiance, and AM 1.5 spectrum (Correct answer)
- 20°C ambient temperature, 800 W/m² irradiance, and no wind
- 0°C cell temperature, 1200 W/m² irradiance, and AM 2.0 spectrum
- 25°C ambient temperature, 1000 W/m² irradiance, and 10% humidity
Correct answer: 25°C cell temperature, 1000 W/m² irradiance, and AM 1.5 spectrum
STC defines PV panel performance at 25°C cell temperature, 1000 W/m² irradiance, and AM 1.5 solar spectrum, providing a universal standard for comparing module wattage ratings.
Question 5: In net metering, what happens when a facility's renewable energy system produces more electricity than the facility consumes?
- The excess electricity is automatically stored in on-site batteries
- The excess electricity is credited to the customer's bill at retail rates (Correct answer)
- The excess electricity is automatically curtailed to prevent grid overload
- The utility purchases the excess only at avoided cost wholesale rates
Correct answer: The excess electricity is credited to the customer's bill at retail rates
Net metering allows customers to receive bill credits at retail rates for excess electricity fed back to the grid, which offset future electricity charges.
Question 6: What is a Solar Renewable Energy Certificate (SREC)?
- A certification required for solar installers to work on commercial projects
- A tradeable certificate representing 1 MWh of electricity generated from solar energy (Correct answer)
- A federal tax credit equal to 30% of the cost of a solar installation
- A utility incentive program that pays a fixed rate per kWh for solar power production
Correct answer: A tradeable certificate representing 1 MWh of electricity generated from solar energy
An SREC represents 1 MWh of solar electricity generated and can be sold separately from the electricity itself to utilities needing to meet Renewable Portfolio Standards.
Question 7: Which factor most significantly reduces actual PV energy output compared to STC-rated output?
- Orientation angle deviation of 5–10° from true south
- Aggregate system losses including temperature derating, wiring, inverter efficiency, and soiling (Correct answer)
- Variation in utility grid voltage throughout the day
- Seasonal changes in daylight hours at the installation site
Correct answer: Aggregate system losses including temperature derating, wiring, inverter efficiency, and soiling
Aggregate system losses—temperature derating, wiring resistance, inverter efficiency, soiling, and mismatch—typically reduce real-world output by 20–30% compared to STC ratings.
