NABCEP Solar Heating Installer
Certification Exam Practice Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
Download Pdf
1. Which of the following is the most common type of solar collector
used for residential water heating?
A. Flat-plate collector
B. Evacuated tube collector
C. Concentrating collector
D. Parabolic trough
Rationale: Flat-plate collectors are widely used in residential solar water
heating systems due to their simplicity, durability, and cost-effectiveness.
2. What is the main function of a heat transfer fluid in a solar thermal
system?
, A. Generate electricity
B. Transfer heat from the collector to the storage tank
C. Absorb sunlight
D. Cool the system
Rationale: The heat transfer fluid (often water or glycol mixture) moves
the absorbed thermal energy from the solar collector to the storage or
load.
3. Which of the following is a common material used for piping in solar
thermal systems?
A. Steel
B. PVC
C. Copper
D. Aluminum
Rationale: Copper is preferred for its high thermal conductivity, corrosion
resistance, and ability to withstand high temperatures.
4. What is the typical efficiency range for a well-designed flat-plate solar
collector?
A. 10–20%
B. 20–35%
C. 35–50%
D. 50–70%
,Rationale: Flat-plate collectors typically convert 35–50% of incident solar
energy into usable heat under optimal conditions.
5. Which factor has the greatest impact on solar collector performance?
A. Pipe diameter
B. Mounting height
C. Incident solar radiation
D. Color of the building
Rationale: The amount of solar radiation striking the collector surface
directly determines the energy available for heating.
6. In a closed-loop solar water heating system, why is an antifreeze
solution often used?
A. Increase solar absorption
B. Reduce heat loss
C. Prevent freezing in cold climates
D. Improve flow rate
Rationale: Antifreeze solutions (glycol mixtures) prevent the system fluid
from freezing, which could damage the collectors and piping in winter.
7. What is the purpose of an expansion tank in a solar thermal system?
A. Generate pressure
B. Accommodate thermal expansion of the fluid
C. Store hot water
D. Reduce system efficiency
, Rationale: As the heat transfer fluid heats, it expands; the expansion tank
prevents overpressure by providing space for this expansion.
8. Which type of solar water heating system uses a pump to circulate
fluid?
A. Direct thermosiphon
B. Passive batch system
C. Active system
D. Integral collector-storage
Rationale: Active systems rely on pumps or controllers to circulate fluid
between the collector and storage, unlike passive systems that rely on
natural convection.
9. What is the recommended slope angle for a solar collector in the
northern hemisphere for year-round performance?
A. 10°
B. 30°
C. Latitude of the installation site ± 10°
D. 90°
Rationale: Aligning the collector slope to the latitude optimizes annual
solar gain, with minor adjustments depending on seasonal priorities.
10. Which component is essential to prevent overheating in a solar
water heating system?
A. Circulation pump
Certification Exam Practice Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
Download Pdf
1. Which of the following is the most common type of solar collector
used for residential water heating?
A. Flat-plate collector
B. Evacuated tube collector
C. Concentrating collector
D. Parabolic trough
Rationale: Flat-plate collectors are widely used in residential solar water
heating systems due to their simplicity, durability, and cost-effectiveness.
2. What is the main function of a heat transfer fluid in a solar thermal
system?
, A. Generate electricity
B. Transfer heat from the collector to the storage tank
C. Absorb sunlight
D. Cool the system
Rationale: The heat transfer fluid (often water or glycol mixture) moves
the absorbed thermal energy from the solar collector to the storage or
load.
3. Which of the following is a common material used for piping in solar
thermal systems?
A. Steel
B. PVC
C. Copper
D. Aluminum
Rationale: Copper is preferred for its high thermal conductivity, corrosion
resistance, and ability to withstand high temperatures.
4. What is the typical efficiency range for a well-designed flat-plate solar
collector?
A. 10–20%
B. 20–35%
C. 35–50%
D. 50–70%
,Rationale: Flat-plate collectors typically convert 35–50% of incident solar
energy into usable heat under optimal conditions.
5. Which factor has the greatest impact on solar collector performance?
A. Pipe diameter
B. Mounting height
C. Incident solar radiation
D. Color of the building
Rationale: The amount of solar radiation striking the collector surface
directly determines the energy available for heating.
6. In a closed-loop solar water heating system, why is an antifreeze
solution often used?
A. Increase solar absorption
B. Reduce heat loss
C. Prevent freezing in cold climates
D. Improve flow rate
Rationale: Antifreeze solutions (glycol mixtures) prevent the system fluid
from freezing, which could damage the collectors and piping in winter.
7. What is the purpose of an expansion tank in a solar thermal system?
A. Generate pressure
B. Accommodate thermal expansion of the fluid
C. Store hot water
D. Reduce system efficiency
, Rationale: As the heat transfer fluid heats, it expands; the expansion tank
prevents overpressure by providing space for this expansion.
8. Which type of solar water heating system uses a pump to circulate
fluid?
A. Direct thermosiphon
B. Passive batch system
C. Active system
D. Integral collector-storage
Rationale: Active systems rely on pumps or controllers to circulate fluid
between the collector and storage, unlike passive systems that rely on
natural convection.
9. What is the recommended slope angle for a solar collector in the
northern hemisphere for year-round performance?
A. 10°
B. 30°
C. Latitude of the installation site ± 10°
D. 90°
Rationale: Aligning the collector slope to the latitude optimizes annual
solar gain, with minor adjustments depending on seasonal priorities.
10. Which component is essential to prevent overheating in a solar
water heating system?
A. Circulation pump
