Certification Exam Practice Questions

NABCEP Solar Heating Installer Certification Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• Which of the following is the most common type of solar collector

used for residential water heating?

• Flat-plate collector
• Evacuated tube collector
• Concentrating collector
• Parabolic trough

Rationale: Flat-plate collectors are widely used in residential solar water

heating systems due to their simplicity, durability, and cost-effectiveness.

• What is the main function of a heat transfer fluid in a solar thermal

system? 1 / 4

• Generate electricity
• Transfer heat from the collector to the storage tank
• Absorb sunlight
• 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.

• Which of the following is a common material used for piping in solar

thermal systems?

• Steel

B. PVC

• Copper
• Aluminum

Rationale: Copper is preferred for its high thermal conductivity, corrosion

resistance, and ability to withstand high temperatures.

• 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% 2 / 4

Rationale: Flat-plate collectors typically convert 35–50% of incident solar

energy into usable heat under optimal conditions.

• Which factor has the greatest impact on solar collector performance?
• Pipe diameter
• Mounting height
• Incident solar radiation
• Color of the building

Rationale: The amount of solar radiation striking the collector surface

directly determines the energy available for heating.

• In a closed-loop solar water heating system, why is an antifreeze

solution often used?

• Increase solar absorption
• Reduce heat loss
• Prevent freezing in cold climates
• Improve flow rate

Rationale: Antifreeze solutions (glycol mixtures) prevent the system fluid

from freezing, which could damage the collectors and piping in winter.

• What is the purpose of an expansion tank in a solar thermal system?
• Generate pressure
• Accommodate thermal expansion of the fluid
• Store hot water
• Reduce system efficiency 3 / 4

Rationale: As the heat transfer fluid heats, it expands; the expansion tank

prevents overpressure by providing space for this expansion.

• Which type of solar water heating system uses a pump to circulate

fluid?

• Direct thermosiphon
• Passive batch system
• Active system
• 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.

• What is the recommended slope angle for a solar collector in the

northern hemisphere for year-round performance?

A. 10°

B. 30°

• 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.

• Which component is essential to prevent overheating in a solar

water heating system?

• Circulation pump
• / 4