CO Solar Thermal Contractor Exam
Questions And Correct Answers
(Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
Which type of solar collector is best suited for high-temperature applications
such as industrial process heat?
A. Flat-plate collector
B. Concentrating collector
C. Unglazed collector
D. Batch collector
Concentrating collectors focus sunlight to achieve higher temperatures,
suitable for industrial processes.
1. What is the primary function of a solar thermal storage tank?
A. Convert sunlight into electricity
B. Store heat for later use
C. Filter water
D. Cool the fluid
The storage tank holds heated fluid, allowing energy to be used when
sunlight is not available.
2. Which fluid is commonly used in closed-loop solar thermal systems to
prevent freezing?
A. Water
B. Glycol-water mixture
C. Oil
D. Saltwater
Glycol prevents freezing in colder climates, ensuring system
reliability.
3. What is the purpose of an expansion tank in a solar thermal system?
A. Heat the water
B. Generate electricity
, C. Accommodate fluid expansion due to heating
D. Remove impurities
Expansion tanks prevent excessive pressure build-up when the fluid
heats and expands.
4. Which component regulates the flow of heat transfer fluid in a solar
thermal system?
A. Collector
B. Pump
C. Storage tank
D. Thermostat
Pumps maintain fluid circulation through the collectors and system
piping.
5. What is the typical efficiency range of a flat-plate solar collector?
A. 5–10%
B. 20–30%
C. 40–70%
D. 80–90%
Flat-plate collectors generally achieve 40–70% efficiency depending
on design and conditions.
6. Which factor most affects the performance of a solar thermal collector?
A. Color of the pipes
B. Incident solar radiation
C. Brand of pump
D. Room temperature
The amount of sunlight striking the collector directly influences heat
output.
7. In a direct (open-loop) solar water heating system, the water:
A. Circulates through a heat exchanger only
B. Flows directly through the collector
C. Is stored in a separate tank
D. Is always mixed with antifreeze
Direct systems heat potable water directly in the collector and store it
for use.
8. Which solar collector is ideal for swimming pool heating?
A. Flat-plate collector
B. Unglazed collector
C. Concentrating collector
, D. Evacuated tube collector
Unglazed collectors are cost-effective and work well at low
temperatures like pool water heating.
9. What is the primary advantage of evacuated tube collectors over flat-
plate collectors?
A. Cheaper installation
B. Simpler design
C. Higher efficiency in cold or cloudy conditions
D. No maintenance required
Evacuated tube collectors reduce heat loss and perform better in low
temperatures.
10. What is the purpose of a solar controller in a thermal system?
A. Store heat
B. Control pump operation based on temperature differences
C. Generate electricity
D. Filter the fluid
The controller turns the circulation pump on or off depending on
temperature readings to optimize performance.
11. What is the main hazard associated with pressurized solar
thermal systems?
A. Electrical shock
B. Excessive pressure leading to leaks or bursts
C. Sunburn
D. Water contamination
Pressurized fluids can rupture piping or tanks if pressure is not
properly managed.
12. Which material is most commonly used for solar collector
absorber plates?
A. Copper or aluminum
B. Stainless steel
C. Plastic
D. Glass
Copper and aluminum have high thermal conductivity, making them
ideal for absorbing solar heat.
13. In a solar thermal system, stagnation occurs when:
A. The pump circulates too fast
B. Fluid stops circulating while the collector is exposed to the sun
Questions And Correct Answers
(Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
Which type of solar collector is best suited for high-temperature applications
such as industrial process heat?
A. Flat-plate collector
B. Concentrating collector
C. Unglazed collector
D. Batch collector
Concentrating collectors focus sunlight to achieve higher temperatures,
suitable for industrial processes.
1. What is the primary function of a solar thermal storage tank?
A. Convert sunlight into electricity
B. Store heat for later use
C. Filter water
D. Cool the fluid
The storage tank holds heated fluid, allowing energy to be used when
sunlight is not available.
2. Which fluid is commonly used in closed-loop solar thermal systems to
prevent freezing?
A. Water
B. Glycol-water mixture
C. Oil
D. Saltwater
Glycol prevents freezing in colder climates, ensuring system
reliability.
3. What is the purpose of an expansion tank in a solar thermal system?
A. Heat the water
B. Generate electricity
, C. Accommodate fluid expansion due to heating
D. Remove impurities
Expansion tanks prevent excessive pressure build-up when the fluid
heats and expands.
4. Which component regulates the flow of heat transfer fluid in a solar
thermal system?
A. Collector
B. Pump
C. Storage tank
D. Thermostat
Pumps maintain fluid circulation through the collectors and system
piping.
5. What is the typical efficiency range of a flat-plate solar collector?
A. 5–10%
B. 20–30%
C. 40–70%
D. 80–90%
Flat-plate collectors generally achieve 40–70% efficiency depending
on design and conditions.
6. Which factor most affects the performance of a solar thermal collector?
A. Color of the pipes
B. Incident solar radiation
C. Brand of pump
D. Room temperature
The amount of sunlight striking the collector directly influences heat
output.
7. In a direct (open-loop) solar water heating system, the water:
A. Circulates through a heat exchanger only
B. Flows directly through the collector
C. Is stored in a separate tank
D. Is always mixed with antifreeze
Direct systems heat potable water directly in the collector and store it
for use.
8. Which solar collector is ideal for swimming pool heating?
A. Flat-plate collector
B. Unglazed collector
C. Concentrating collector
, D. Evacuated tube collector
Unglazed collectors are cost-effective and work well at low
temperatures like pool water heating.
9. What is the primary advantage of evacuated tube collectors over flat-
plate collectors?
A. Cheaper installation
B. Simpler design
C. Higher efficiency in cold or cloudy conditions
D. No maintenance required
Evacuated tube collectors reduce heat loss and perform better in low
temperatures.
10. What is the purpose of a solar controller in a thermal system?
A. Store heat
B. Control pump operation based on temperature differences
C. Generate electricity
D. Filter the fluid
The controller turns the circulation pump on or off depending on
temperature readings to optimize performance.
11. What is the main hazard associated with pressurized solar
thermal systems?
A. Electrical shock
B. Excessive pressure leading to leaks or bursts
C. Sunburn
D. Water contamination
Pressurized fluids can rupture piping or tanks if pressure is not
properly managed.
12. Which material is most commonly used for solar collector
absorber plates?
A. Copper or aluminum
B. Stainless steel
C. Plastic
D. Glass
Copper and aluminum have high thermal conductivity, making them
ideal for absorbing solar heat.
13. In a solar thermal system, stagnation occurs when:
A. The pump circulates too fast
B. Fluid stops circulating while the collector is exposed to the sun
