VA Alternative Energy System
Contracting Practice Exam –Questions
And Correct Answers (Verified Answers)
Plus Rationales 2025/2026 Q&A | Instant
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Question 1: Which component is critical for preventing overcharging in a solar
energy system with battery storage?
Option A: Inverter
Option B: MPPT controller
Option C: Charge controller
Option D: DC disconnect - ANSWER -Correct ANSWER: C - Charge controller
Explanation: The charge controller regulates the energy flowing to the batteries,
preventing overcharge and extending battery life.
Question 2: What calculation is essential when determining the wiring size in a
photovoltaic installation?
Option A: Load factor
Option B: Voltage drop calculation
Option C: Inverter efficiency
Option D: String configuration - ANSWER -Correct ANSWER: B - Voltage drop
calculation
Explanation: Calculating voltage drop ensures that wiring is appropriately sized to
minimize energy loss over distance.
Question 3: Which factor is most important when estimating a solar system's cost?
,Option A: Roof color
Option B: System efficiency
Option C: Module degradation rate
Option D: Local solar irradiance - ANSWER -Correct ANSWER: D - Local solar
irradiance
Explanation: Local solar irradiance directly impacts energy production estimates
and system cost-effectiveness.
Question 4: What does the term "DC disconnect" refer to in PV systems?
Option A: A device that converts AC to DC
Option B: A safety switch to isolate the DC circuits
Option C: A method to reduce DC voltage
Option D: A tool to measure direct current - ANSWER -Correct ANSWER: B - A
safety switch to isolate the DC circuits
Explanation: A DC disconnect allows safe maintenance by isolating the DC
portion of the system during service.
Question 5: Which of the following is a typical challenge when installing rooftop
PV systems?
Option A: Low solar irradiance
Option B: Shading and roof orientation
Option C: Excessive battery storage
Option D: Too much wind - ANSWER -Correct ANSWER: B - Shading and roof
orientation
Explanation: Shading and roof orientation critically affect the performance and
design of rooftop solar systems.
Question 6: How is the overall efficiency of a photovoltaic module determined?
,Option A: Ratio of AC output to battery capacity
Option B: Ratio of DC power output to solar irradiance input
Option C: Ratio of series resistance to shunt resistance
Option D: Ratio of inverter efficiency to module size - ANSWER -Correct
ANSWER: B - Ratio of DC power output to solar irradiance input
Explanation: Efficiency is measured by comparing the electrical power output to
the solar power incident on the panel's surface.
Question 7: What is the purpose of bypass diodes in a PV module?
Option A: To increase voltage output
Option B: To protect against reverse bias in shaded cells
Option C: To store excess energy
Option D: To convert DC to AC - ANSWER -Correct ANSWER: B - To protect
against reverse bias in shaded cells
Explanation: Bypass diodes prevent the entire string from losing output if a single
cell becomes shaded.
Question 8: Which electrical parameter is crucial when designing series
connections of PV modules?
Option A: Frequency
Option B: Voltage
Option C: Capacitance
Option D: Inductance - ANSWER -Correct ANSWER: B - Voltage
Explanation: In series connections, the voltages of individual modules add up;
proper voltage matching is essential for system performance.
Question 9: What is the typical lifetime performance degradation rate of a quality
PV module per year?
Option A: 0.1-0.2%
, Option B: 0.5-1%
Option C: 2-3%
Option D: 5-6% - ANSWER -Correct ANSWER: B - 0.5-1%
Explanation: High-quality PV modules generally degrade at a rate of about 0.5-1%
per year, ensuring long-term energy production.
Question 10: Which code or standard is most often referenced for electrical safety
in solar installations?
Option A: NFPA 70 (NEC)
Option B: IEEE 1547
Option C: UL 1703
Option D: IEC 61215 - ANSWER -Correct ANSWER: A - NFPA 70 (NEC)
Explanation: The National Electrical Code (NEC) provides essential guidelines for
safe electrical installations, including solar systems.
Question 21: Which solar component directly converts sunlight into DC
electricity?
Option A: Inverter
Option B: PV module
Option C: Charge controller
Option D: Transformer - ANSWER -Correct ANSWER: B - PV module
Explanation: The PV module, made up of individual cells, is responsible for
converting sunlight into direct current electricity.
Question 22: What is the effect of high temperatures on PV module performance?
Option A: Increased output efficiency
Option B: Reduced output efficiency
Option C: No effect
Contracting Practice Exam –Questions
And Correct Answers (Verified Answers)
Plus Rationales 2025/2026 Q&A | Instant
Download Pdf
Question 1: Which component is critical for preventing overcharging in a solar
energy system with battery storage?
Option A: Inverter
Option B: MPPT controller
Option C: Charge controller
Option D: DC disconnect - ANSWER -Correct ANSWER: C - Charge controller
Explanation: The charge controller regulates the energy flowing to the batteries,
preventing overcharge and extending battery life.
Question 2: What calculation is essential when determining the wiring size in a
photovoltaic installation?
Option A: Load factor
Option B: Voltage drop calculation
Option C: Inverter efficiency
Option D: String configuration - ANSWER -Correct ANSWER: B - Voltage drop
calculation
Explanation: Calculating voltage drop ensures that wiring is appropriately sized to
minimize energy loss over distance.
Question 3: Which factor is most important when estimating a solar system's cost?
,Option A: Roof color
Option B: System efficiency
Option C: Module degradation rate
Option D: Local solar irradiance - ANSWER -Correct ANSWER: D - Local solar
irradiance
Explanation: Local solar irradiance directly impacts energy production estimates
and system cost-effectiveness.
Question 4: What does the term "DC disconnect" refer to in PV systems?
Option A: A device that converts AC to DC
Option B: A safety switch to isolate the DC circuits
Option C: A method to reduce DC voltage
Option D: A tool to measure direct current - ANSWER -Correct ANSWER: B - A
safety switch to isolate the DC circuits
Explanation: A DC disconnect allows safe maintenance by isolating the DC
portion of the system during service.
Question 5: Which of the following is a typical challenge when installing rooftop
PV systems?
Option A: Low solar irradiance
Option B: Shading and roof orientation
Option C: Excessive battery storage
Option D: Too much wind - ANSWER -Correct ANSWER: B - Shading and roof
orientation
Explanation: Shading and roof orientation critically affect the performance and
design of rooftop solar systems.
Question 6: How is the overall efficiency of a photovoltaic module determined?
,Option A: Ratio of AC output to battery capacity
Option B: Ratio of DC power output to solar irradiance input
Option C: Ratio of series resistance to shunt resistance
Option D: Ratio of inverter efficiency to module size - ANSWER -Correct
ANSWER: B - Ratio of DC power output to solar irradiance input
Explanation: Efficiency is measured by comparing the electrical power output to
the solar power incident on the panel's surface.
Question 7: What is the purpose of bypass diodes in a PV module?
Option A: To increase voltage output
Option B: To protect against reverse bias in shaded cells
Option C: To store excess energy
Option D: To convert DC to AC - ANSWER -Correct ANSWER: B - To protect
against reverse bias in shaded cells
Explanation: Bypass diodes prevent the entire string from losing output if a single
cell becomes shaded.
Question 8: Which electrical parameter is crucial when designing series
connections of PV modules?
Option A: Frequency
Option B: Voltage
Option C: Capacitance
Option D: Inductance - ANSWER -Correct ANSWER: B - Voltage
Explanation: In series connections, the voltages of individual modules add up;
proper voltage matching is essential for system performance.
Question 9: What is the typical lifetime performance degradation rate of a quality
PV module per year?
Option A: 0.1-0.2%
, Option B: 0.5-1%
Option C: 2-3%
Option D: 5-6% - ANSWER -Correct ANSWER: B - 0.5-1%
Explanation: High-quality PV modules generally degrade at a rate of about 0.5-1%
per year, ensuring long-term energy production.
Question 10: Which code or standard is most often referenced for electrical safety
in solar installations?
Option A: NFPA 70 (NEC)
Option B: IEEE 1547
Option C: UL 1703
Option D: IEC 61215 - ANSWER -Correct ANSWER: A - NFPA 70 (NEC)
Explanation: The National Electrical Code (NEC) provides essential guidelines for
safe electrical installations, including solar systems.
Question 21: Which solar component directly converts sunlight into DC
electricity?
Option A: Inverter
Option B: PV module
Option C: Charge controller
Option D: Transformer - ANSWER -Correct ANSWER: B - PV module
Explanation: The PV module, made up of individual cells, is responsible for
converting sunlight into direct current electricity.
Question 22: What is the effect of high temperatures on PV module performance?
Option A: Increased output efficiency
Option B: Reduced output efficiency
Option C: No effect
