NABCEP PV Installation Professional
Certification Practice Exam 100
Questions And Correct Answers
(Verified Answers) Plus Rationales
2026 Q&A Instant Download Pdf
1. A residential PV system consists of 12 modules rated at 450 W each. What
is the total DC nameplate capacity?
A. 3.6 kW
B. 4.5 kW
C. 5.4 kW
D. 6.0 kW
C. 5.4 kW
Rationale: Total capacity = module wattage × quantity = 450 W × 12 = 5,400
W = 5.4 kW. This fundamental calculation determines inverter compatibility
and conductor sizing.
2. Which instrument is used to measure solar irradiance at a site?
A. Clamp meter
B. Megohmmeter
C. Pyranometer
D. Oscilloscope
C. Pyranometer
Rationale: A pyranometer measures global solar irradiance in watts per
square meter (W/m²). This data validates production estimates and site
suitability.
,3. In the Northern Hemisphere, which roof orientation generally provides the
highest annual energy production for a fixed PV array?
A. East
B. West
C. North
D. South
D. South
Rationale: South-facing arrays receive the greatest annual solar exposure in
the Northern Hemisphere. Southeast and southwest orientations can perform
well but typically produce less annually than true south.
4. What is the primary effect of increased cell temperature on a crystalline
silicon PV module?
A. Short-circuit current increases dramatically
B. Open-circuit voltage decreases
C. Power output increases
D. Module weight increases
B. Open-circuit voltage decreases
Rationale: As cell temperature rises, open-circuit voltage (Voc) decreases
significantly (typically -0.3% to -0.4% per °C), while current changes only
slightly. This affects string voltage calculations.
5. Which component converts DC electricity from PV modules into usable AC
electricity?
A. Charge controller
B. Combiner box
C. Inverter
D. Disconnect switch
C. Inverter
,Rationale: The inverter transforms DC power from the array into AC power
suitable for loads or grid interconnection while performing maximum power
point tracking and protection functions.
6. What is the primary purpose of a combiner box in a PV system?
A. Increase system voltage
B. Convert DC to AC
C. Combine multiple string outputs into one circuit
D. Store excess energy
C. Combine multiple string outputs into one circuit
Rationale: A combiner box aggregates parallel string outputs, provides
overcurrent protection, and simplifies wiring to the inverter or charge
controller.
7. Which NEC section establishes requirements for working spaces around
live electrical equipment?
A. 690.12
B. 110.26
C. 705.12
D. 250.122
B. 110.26
Rationale: NEC 110.26 specifies minimum working clearances around
electrical equipment to ensure safe operation and maintenance. PV systems
must comply with these requirements.
8. What is the primary function of an MPPT charge controller?
A. Convert AC to DC
B. Prevent overvoltage only
C. Maximize power extraction from the array
D. Store energy in batteries
, C. Maximize power extraction from the array
Rationale: Maximum Power Point Tracking continuously adjusts operating
voltage and current to extract the maximum available power from PV
modules under varying irradiance and temperature conditions.
9. When PV modules are connected in series, which electrical parameter
increases?
A. Current
B. Voltage
C. Power
D. Resistance
B. Voltage
Rationale: Series connection adds voltages while current remains constant.
This allows higher system voltages for efficient power transmission and
inverter compatibility.
10. What is the primary purpose of grounding a PV system?
A. Increase voltage stability
B. Protect against electric shock and fire hazards
C. Improve module efficiency
D. Reduce wire size requirements
B. Protect against electric shock and fire hazards
Rationale: Grounding provides a low-resistance path for fault current,
enabling overcurrent devices to operate and reducing shock and fire risks
from insulation failure or lightning.
11. A PV string produces 350 V at 8 A. What is the power output?
A. 2,400 W
B. 2,800 W
Certification Practice Exam 100
Questions And Correct Answers
(Verified Answers) Plus Rationales
2026 Q&A Instant Download Pdf
1. A residential PV system consists of 12 modules rated at 450 W each. What
is the total DC nameplate capacity?
A. 3.6 kW
B. 4.5 kW
C. 5.4 kW
D. 6.0 kW
C. 5.4 kW
Rationale: Total capacity = module wattage × quantity = 450 W × 12 = 5,400
W = 5.4 kW. This fundamental calculation determines inverter compatibility
and conductor sizing.
2. Which instrument is used to measure solar irradiance at a site?
A. Clamp meter
B. Megohmmeter
C. Pyranometer
D. Oscilloscope
C. Pyranometer
Rationale: A pyranometer measures global solar irradiance in watts per
square meter (W/m²). This data validates production estimates and site
suitability.
,3. In the Northern Hemisphere, which roof orientation generally provides the
highest annual energy production for a fixed PV array?
A. East
B. West
C. North
D. South
D. South
Rationale: South-facing arrays receive the greatest annual solar exposure in
the Northern Hemisphere. Southeast and southwest orientations can perform
well but typically produce less annually than true south.
4. What is the primary effect of increased cell temperature on a crystalline
silicon PV module?
A. Short-circuit current increases dramatically
B. Open-circuit voltage decreases
C. Power output increases
D. Module weight increases
B. Open-circuit voltage decreases
Rationale: As cell temperature rises, open-circuit voltage (Voc) decreases
significantly (typically -0.3% to -0.4% per °C), while current changes only
slightly. This affects string voltage calculations.
5. Which component converts DC electricity from PV modules into usable AC
electricity?
A. Charge controller
B. Combiner box
C. Inverter
D. Disconnect switch
C. Inverter
,Rationale: The inverter transforms DC power from the array into AC power
suitable for loads or grid interconnection while performing maximum power
point tracking and protection functions.
6. What is the primary purpose of a combiner box in a PV system?
A. Increase system voltage
B. Convert DC to AC
C. Combine multiple string outputs into one circuit
D. Store excess energy
C. Combine multiple string outputs into one circuit
Rationale: A combiner box aggregates parallel string outputs, provides
overcurrent protection, and simplifies wiring to the inverter or charge
controller.
7. Which NEC section establishes requirements for working spaces around
live electrical equipment?
A. 690.12
B. 110.26
C. 705.12
D. 250.122
B. 110.26
Rationale: NEC 110.26 specifies minimum working clearances around
electrical equipment to ensure safe operation and maintenance. PV systems
must comply with these requirements.
8. What is the primary function of an MPPT charge controller?
A. Convert AC to DC
B. Prevent overvoltage only
C. Maximize power extraction from the array
D. Store energy in batteries
, C. Maximize power extraction from the array
Rationale: Maximum Power Point Tracking continuously adjusts operating
voltage and current to extract the maximum available power from PV
modules under varying irradiance and temperature conditions.
9. When PV modules are connected in series, which electrical parameter
increases?
A. Current
B. Voltage
C. Power
D. Resistance
B. Voltage
Rationale: Series connection adds voltages while current remains constant.
This allows higher system voltages for efficient power transmission and
inverter compatibility.
10. What is the primary purpose of grounding a PV system?
A. Increase voltage stability
B. Protect against electric shock and fire hazards
C. Improve module efficiency
D. Reduce wire size requirements
B. Protect against electric shock and fire hazards
Rationale: Grounding provides a low-resistance path for fault current,
enabling overcurrent devices to operate and reducing shock and fire risks
from insulation failure or lightning.
11. A PV string produces 350 V at 8 A. What is the power output?
A. 2,400 W
B. 2,800 W
