NABCEP SOLAR HEATING INSTALLER
CERTIFICATION EXAM QUESTION AND
CORRECT ANSWERS(VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A
INSTANT DOWNLOAD PDF
1. What is the primary purpose of a solar thermal collector?
A. Generate electricity
B. Store hot water
C. Heat air for ventilation
D. Absorb solar radiation and convert it to heat
Answer: D
Rationale: Solar thermal collectors are designed to absorb sunlight and
convert it into usable heat for water or space heating.
2. Which type of solar thermal collector is most commonly used for residential
water heating?
A. Concentrating parabolic collector
B. Flat-plate collector
C. Linear Fresnel collector
D. Solar pond
Answer: B
Rationale: Flat-plate collectors are cost-effective, durable, and well-suited
for residential solar water heating systems.
3. An evacuated tube collector is especially advantageous in which condition?
A. High wind areas
B. Cold or cloudy climates
C. Low-latitude regions only
D. Indoor installations
, Answer: B
Rationale: Evacuated tubes reduce heat loss, making them efficient in
colder or less sunny conditions.
4. What is the function of a heat transfer fluid in a closed-loop solar thermal
system?
A. Store potable water
B. Prevent scaling
C. Transfer heat from the collector to the storage tank
D. Increase system pressure
Answer: C
Rationale: Heat transfer fluid carries thermal energy from the collector to
the heat exchanger or storage.
5. Which heat transfer fluid is most commonly used in freeze-prone climates?
A. Distilled water
B. Mineral oil
C. Propylene glycol solution
D. Ethanol
Answer: C
Rationale: Propylene glycol provides freeze protection and is non-toxic,
making it suitable for solar heating systems.
6. What component prevents reverse thermosiphoning at night?
A. Expansion tank
B. Pressure relief valve
C. Check valve
D. Air separator
Answer: C
Rationale: A check valve stops heated fluid from flowing backward and
losing heat at night.
7. What is the primary purpose of an expansion tank?
A. Increase system efficiency
B. Remove air
C. Accommodate fluid expansion due to temperature changes
D. Regulate collector tilt
, Answer: C
Rationale: Fluids expand when heated, and the expansion tank prevents
overpressure damage.
8. In a solar water heating system, what does a differential controller do?
A. Measures solar radiation
B. Regulates flow rate
C. Activates the pump based on temperature differences
D. Controls backup heater
Answer: C
Rationale: Differential controllers compare collector and tank
temperatures to control pump operation.
9. What is the typical optimal tilt angle for a solar thermal collector?
A. Horizontal
B. Latitude minus 30°
C. Approximately equal to site latitude
D. Vertical
Answer: C
Rationale: Tilting collectors near the site latitude maximizes annual solar
energy capture.
10.Which orientation maximizes solar gain in the northern hemisphere?
A. East
B. West
C. True south
D. North
Answer: C
Rationale: South-facing collectors receive the most consistent solar
exposure in the northern hemisphere.
11.What is stagnation temperature?
A. Operating temperature under load
B. Freezing point of fluid
C. Maximum temperature a collector can reach with no heat removal
D. Average daily temperature
Answer: C
CERTIFICATION EXAM QUESTION AND
CORRECT ANSWERS(VERIFIED
ANSWERS) PLUS RATIONALES 2026 Q&A
INSTANT DOWNLOAD PDF
1. What is the primary purpose of a solar thermal collector?
A. Generate electricity
B. Store hot water
C. Heat air for ventilation
D. Absorb solar radiation and convert it to heat
Answer: D
Rationale: Solar thermal collectors are designed to absorb sunlight and
convert it into usable heat for water or space heating.
2. Which type of solar thermal collector is most commonly used for residential
water heating?
A. Concentrating parabolic collector
B. Flat-plate collector
C. Linear Fresnel collector
D. Solar pond
Answer: B
Rationale: Flat-plate collectors are cost-effective, durable, and well-suited
for residential solar water heating systems.
3. An evacuated tube collector is especially advantageous in which condition?
A. High wind areas
B. Cold or cloudy climates
C. Low-latitude regions only
D. Indoor installations
, Answer: B
Rationale: Evacuated tubes reduce heat loss, making them efficient in
colder or less sunny conditions.
4. What is the function of a heat transfer fluid in a closed-loop solar thermal
system?
A. Store potable water
B. Prevent scaling
C. Transfer heat from the collector to the storage tank
D. Increase system pressure
Answer: C
Rationale: Heat transfer fluid carries thermal energy from the collector to
the heat exchanger or storage.
5. Which heat transfer fluid is most commonly used in freeze-prone climates?
A. Distilled water
B. Mineral oil
C. Propylene glycol solution
D. Ethanol
Answer: C
Rationale: Propylene glycol provides freeze protection and is non-toxic,
making it suitable for solar heating systems.
6. What component prevents reverse thermosiphoning at night?
A. Expansion tank
B. Pressure relief valve
C. Check valve
D. Air separator
Answer: C
Rationale: A check valve stops heated fluid from flowing backward and
losing heat at night.
7. What is the primary purpose of an expansion tank?
A. Increase system efficiency
B. Remove air
C. Accommodate fluid expansion due to temperature changes
D. Regulate collector tilt
, Answer: C
Rationale: Fluids expand when heated, and the expansion tank prevents
overpressure damage.
8. In a solar water heating system, what does a differential controller do?
A. Measures solar radiation
B. Regulates flow rate
C. Activates the pump based on temperature differences
D. Controls backup heater
Answer: C
Rationale: Differential controllers compare collector and tank
temperatures to control pump operation.
9. What is the typical optimal tilt angle for a solar thermal collector?
A. Horizontal
B. Latitude minus 30°
C. Approximately equal to site latitude
D. Vertical
Answer: C
Rationale: Tilting collectors near the site latitude maximizes annual solar
energy capture.
10.Which orientation maximizes solar gain in the northern hemisphere?
A. East
B. West
C. True south
D. North
Answer: C
Rationale: South-facing collectors receive the most consistent solar
exposure in the northern hemisphere.
11.What is stagnation temperature?
A. Operating temperature under load
B. Freezing point of fluid
C. Maximum temperature a collector can reach with no heat removal
D. Average daily temperature
Answer: C
