AZ L-93 Solar Thermal Contractor Exam
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Section 1: Solar Thermal Fundamentals
1. What is the primary purpose of a solar thermal energy system?
a. To convert sunlight directly into electrical energy
b. To capture solar radiation and transfer the heat to a useful
application
c. To increase the electrical conductivity of water
d. To convert wind energy into mechanical energy
Rationale: Solar thermal systems collect solar radiation and convert it
into heat. That heat can be transferred to water, air, or another
working fluid for domestic hot water, space heating, pool heating, or
,other thermal applications. Unlike photovoltaic systems, solar thermal
systems do not primarily generate electricity.
2. Which component of a solar thermal system absorbs solar radiation
and converts it into heat?
a. Expansion tank
b. Circulator pump
c. Solar collector
d. Mixing valve
Rationale: The solar collector is designed to absorb incoming solar
radiation and convert it into thermal energy. The collected heat is
transferred to a working fluid, which carries it to a storage tank or
heat exchanger. Other components support circulation, pressure
control, storage, and temperature regulation.
3. What is the primary function of a solar thermal storage tank?
a. To generate additional solar radiation
b. To store collected thermal energy for later use
c. To increase the collector's surface area
d. To eliminate the need for system controls
,Rationale: Solar energy availability varies throughout the day, while
hot water demand may occur at different times. A storage tank holds
heated water or transfers heat to stored water so that the energy
collected during sunny periods can be used later. Proper insulation
reduces standby heat losses.
4. Which type of solar radiation reaches the collector directly from the
sun without being scattered by the atmosphere?
a. Reflected radiation
b. Diffuse radiation
c. Direct beam radiation
d. Ground-emitted radiation
Rationale: Direct beam radiation travels from the sun to the collector
without being scattered. Diffuse radiation has been scattered by
atmospheric particles and clouds. Both direct and diffuse solar
radiation can contribute to the energy collected by many solar
thermal systems, although their relative importance depends on
collector design and weather conditions.
5. What does thermal efficiency describe in a solar thermal collector?
a. The percentage of water that passes through the collector
, b. The amount of electricity consumed by the pump
c. The fraction of incident solar energy converted into useful thermal
energy
d. The percentage of collector surface that is painted black
Rationale: Collector thermal efficiency compares useful heat output
with the solar energy incident on the collector's reference area. It is
affected by solar irradiance, collector temperature, ambient
temperature, optical properties, and heat losses. A collector's
efficiency changes with operating conditions rather than remaining
constant.
6. Which factor generally increases the thermal losses from an
operating solar collector?
a. Lowering the collector temperature
b. Increasing insulation thickness
c. Increasing the temperature difference between the collector and
ambient air
d. Reducing the exposed collector surface area
Rationale: Heat naturally flows from a warmer collector toward cooler
surroundings. A larger temperature difference generally increases
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A| Instant
Download Pdf
Section 1: Solar Thermal Fundamentals
1. What is the primary purpose of a solar thermal energy system?
a. To convert sunlight directly into electrical energy
b. To capture solar radiation and transfer the heat to a useful
application
c. To increase the electrical conductivity of water
d. To convert wind energy into mechanical energy
Rationale: Solar thermal systems collect solar radiation and convert it
into heat. That heat can be transferred to water, air, or another
working fluid for domestic hot water, space heating, pool heating, or
,other thermal applications. Unlike photovoltaic systems, solar thermal
systems do not primarily generate electricity.
2. Which component of a solar thermal system absorbs solar radiation
and converts it into heat?
a. Expansion tank
b. Circulator pump
c. Solar collector
d. Mixing valve
Rationale: The solar collector is designed to absorb incoming solar
radiation and convert it into thermal energy. The collected heat is
transferred to a working fluid, which carries it to a storage tank or
heat exchanger. Other components support circulation, pressure
control, storage, and temperature regulation.
3. What is the primary function of a solar thermal storage tank?
a. To generate additional solar radiation
b. To store collected thermal energy for later use
c. To increase the collector's surface area
d. To eliminate the need for system controls
,Rationale: Solar energy availability varies throughout the day, while
hot water demand may occur at different times. A storage tank holds
heated water or transfers heat to stored water so that the energy
collected during sunny periods can be used later. Proper insulation
reduces standby heat losses.
4. Which type of solar radiation reaches the collector directly from the
sun without being scattered by the atmosphere?
a. Reflected radiation
b. Diffuse radiation
c. Direct beam radiation
d. Ground-emitted radiation
Rationale: Direct beam radiation travels from the sun to the collector
without being scattered. Diffuse radiation has been scattered by
atmospheric particles and clouds. Both direct and diffuse solar
radiation can contribute to the energy collected by many solar
thermal systems, although their relative importance depends on
collector design and weather conditions.
5. What does thermal efficiency describe in a solar thermal collector?
a. The percentage of water that passes through the collector
, b. The amount of electricity consumed by the pump
c. The fraction of incident solar energy converted into useful thermal
energy
d. The percentage of collector surface that is painted black
Rationale: Collector thermal efficiency compares useful heat output
with the solar energy incident on the collector's reference area. It is
affected by solar irradiance, collector temperature, ambient
temperature, optical properties, and heat losses. A collector's
efficiency changes with operating conditions rather than remaining
constant.
6. Which factor generally increases the thermal losses from an
operating solar collector?
a. Lowering the collector temperature
b. Increasing insulation thickness
c. Increasing the temperature difference between the collector and
ambient air
d. Reducing the exposed collector surface area
Rationale: Heat naturally flows from a warmer collector toward cooler
surroundings. A larger temperature difference generally increases
