2026 UPDATED QUESTIONS DOWNLOAD
VA Alternative Energy System Contracting
Practice Exam
Master the Virginia AES specialty exam with this comprehensive -question practice set specifically
updated for the 2026-2027 cycle. This resource covers high-yield topics including NEC Article 690
(Solar PV), Rapid Shutdown requirements, battery storage (ESS), and Virginia Residential Code
(VRC) roof setbacks. Each question features a detailed italicized rationale to ensure you understand
the electrical theory and safety standards required to pass your PSI trade exam on the first try.
1. According to the NEC, what is the maximum DC voltage for a PV system installed on
a one- or two-family dwelling?
A. 120 Volts
B. 600 Volts
C. 1,000 Volts
D. 1,500 Volts
Answer: B. Rationale: For residential dwellings, PV source and output circuits are limited to a
maximum of 600 Volts DC per NEC Article 690.7.
2. Which component is required to convert Direct Current (DC) from solar panels into
Alternating Current (AC) for home use?
A. Rectifier
B. Charge Controller
C. Inverter
D. Transformer
Answer: C. Rationale: The inverter is the primary component that changes the DC power
produced by renewable sources into the 120/240V AC power used by standard household
appliances.
3. "Rapid Shutdown" requirements for PV systems on buildings are intended primarily
to protect:
A. The homeowner's appliances.
B. First responders (firefighters) from electrical shock.
, 2026 UPDATED QUESTIONS DOWNLOAD
C. The utility grid from surges.
D. The solar panels from lightning strikes.
Answer: B. Rationale: Rapid shutdown (NEC 690.12) allows firefighters to de-energize PV
conductors on a roof to a safe level quickly, reducing the risk of shock during emergency
operations.
4. A "Bypass Diode" in a solar module is used to:
A. Increase the total voltage output.
B. Prevent a shaded cell from becoming a resistive load and causing a "hot spot."
C. Store energy for nighttime use.
D. Ground the aluminum frame.
Answer: B. Rationale: If one cell in a string is shaded, it can act as a resistor and overheat; the
diode allows current to "pass by" the shaded area to maintain performance and prevent
damage.
5. In Virginia, what is the minimum required wind speed rating for the mounting
hardware of a wind turbine system?
A. 70 mph
B. 90 mph
C. 115 mph (or local code equivalent)
D. 150 mph
Answer: C. Rationale: Mounting systems must meet the wind load requirements of the Virginia
Uniform Statewide Building Code (VUSBC), which typically references a 115 mph baseline for
structural integrity.
6. Which type of solar thermal system uses a pump to circulate a heat-transfer fluid
through the collectors?
A. Passive (Thermosyphon)
B. Integral Collector Storage (ICS)
C. Active System
D. Gravity-fed System
Answer: C. Rationale: Active systems utilize mechanical pumps and electronic controllers to
move fluids, whereas passive systems rely solely on natural convection and gravity.
7. A "Grid-Tied" system without battery backup will behave how during a utility power
outage?
A. It will continue to power the house.
B. It will shut down immediately (Anti-islanding).
C. It will feed power back into the grid to help utility workers.
D. It will switch to DC mode for the lights.
Answer: B. Rationale: Standard grid-tied inverters must shut down during an outage to prevent
"islanding," which could electrocute utility workers attempting to repair the power lines.
, 2026 UPDATED QUESTIONS DOWNLOAD
8. The "Tilt Angle" of a fixed solar array in Virginia is ideally set to match:
A. The time of day.
B. The local latitude (approx. 37°–39°).
C. The height of the nearest tree.
D. 90 degrees.
Answer: B. Rationale: Setting the tilt to the local latitude maximizes the annual energy
production for a fixed-mount system by aligning with the average sun position throughout the
year.
9. "Net Metering" allows a Virginia customer to:
A. Get free electricity from the government.
B. Receive credit on their utility bill for excess energy sent back to the grid.
C. Only use solar power at night.
D. Connect their panels to the neighbor's house for sharing.
Answer: B. Rationale: Net metering tracks the "net" difference between what the customer
produces and what they consume, essentially using the grid as a virtual battery.
10. What is the purpose of a "Charge Controller" in a system with battery storage?
A. To turn the wind turbine faster.
B. To prevent batteries from overcharging and being damaged.
C. To clean the biomass fuel.
D. To measure the temperature of the inverter.
Answer: B. Rationale: The charge controller regulates the voltage and current coming from the
PV or wind source to ensure the battery bank remains at a safe state of charge.
11. Which NEC Article specifically covers Solar Photovoltaic (PV) Systems?
A. Article 250
B. Article 430
C. Article 690
D. Article 702
Answer: C. Rationale: NEC Article 690 is dedicated to the unique wiring, grounding, and
disconnecting requirements of PV systems.
12. "Azimuth" refers to what in a solar installation?
A. The angle of the sun above the horizon.
B. The compass direction the panels face (e.g., 180° for True South).
C. The weight of the panel per square foot.
D. The efficiency rating of the cells.
Answer: B. Rationale: For maximum production in the Northern Hemisphere, the ideal azimuth
is 180 degrees (True South) to capture the most sunlight.
13. A "Combiner Box" is used to:
A. Mix biomass fuel types.
B. Aggregate multiple PV strings into a single set of larger output conductors.
, 2026 UPDATED QUESTIONS DOWNLOAD
C. Store spare fuses.
D. Convert AC power back into DC power.
Answer: B. Rationale: It brings together the parallel wiring of multiple solar rows (strings) into
one output going to the inverter or charge controller.
14. What color is the insulation for a "Grounding Electrode Conductor" in an AES
system?
A. Red
B. Black
C. Green or Bare
D. White
Answer: C. Rationale: Per NEC standards, green insulation or bare copper is used for
grounding to identify it as a safety path for fault currents.
15. "Irradiance" is measured in which of the following units?
A. Volts per square inch.
B. Watts per square meter (
).
C. Amps per hour.
D. Pounds per square foot.
Answer: B. Rationale: Irradiance is the measurement of the power of sunlight (radiant flux)
hitting a specific surface area.
16. Fall protection is required in Virginia when working on a roof or surface higher than:
A. 4 feet
B. 6 feet
C. 10 feet
D. 12 feet
Answer: B. Rationale: OSHA and Virginia state safety standards generally require fall
protection (harnesses, guardrails) for any work performed at heights of 6 feet or more.
17. A "Governor" on a wind turbine is used to prevent:
A. The turbine from starting.
B. Overspeeding in high wind conditions.
C. The blades from turning at night.
D. Theft of the turbine.
Answer: B. Rationale: A governor (or braking system) slows the blades during high winds to
prevent mechanical failure or overheating of the generator.
18. In biomass energy, a "Gasifier" converts solid organic matter into:
A. Liquid gasoline.
B. Syngas (Synthetic Gas).
VA Alternative Energy System Contracting
Practice Exam
Master the Virginia AES specialty exam with this comprehensive -question practice set specifically
updated for the 2026-2027 cycle. This resource covers high-yield topics including NEC Article 690
(Solar PV), Rapid Shutdown requirements, battery storage (ESS), and Virginia Residential Code
(VRC) roof setbacks. Each question features a detailed italicized rationale to ensure you understand
the electrical theory and safety standards required to pass your PSI trade exam on the first try.
1. According to the NEC, what is the maximum DC voltage for a PV system installed on
a one- or two-family dwelling?
A. 120 Volts
B. 600 Volts
C. 1,000 Volts
D. 1,500 Volts
Answer: B. Rationale: For residential dwellings, PV source and output circuits are limited to a
maximum of 600 Volts DC per NEC Article 690.7.
2. Which component is required to convert Direct Current (DC) from solar panels into
Alternating Current (AC) for home use?
A. Rectifier
B. Charge Controller
C. Inverter
D. Transformer
Answer: C. Rationale: The inverter is the primary component that changes the DC power
produced by renewable sources into the 120/240V AC power used by standard household
appliances.
3. "Rapid Shutdown" requirements for PV systems on buildings are intended primarily
to protect:
A. The homeowner's appliances.
B. First responders (firefighters) from electrical shock.
, 2026 UPDATED QUESTIONS DOWNLOAD
C. The utility grid from surges.
D. The solar panels from lightning strikes.
Answer: B. Rationale: Rapid shutdown (NEC 690.12) allows firefighters to de-energize PV
conductors on a roof to a safe level quickly, reducing the risk of shock during emergency
operations.
4. A "Bypass Diode" in a solar module is used to:
A. Increase the total voltage output.
B. Prevent a shaded cell from becoming a resistive load and causing a "hot spot."
C. Store energy for nighttime use.
D. Ground the aluminum frame.
Answer: B. Rationale: If one cell in a string is shaded, it can act as a resistor and overheat; the
diode allows current to "pass by" the shaded area to maintain performance and prevent
damage.
5. In Virginia, what is the minimum required wind speed rating for the mounting
hardware of a wind turbine system?
A. 70 mph
B. 90 mph
C. 115 mph (or local code equivalent)
D. 150 mph
Answer: C. Rationale: Mounting systems must meet the wind load requirements of the Virginia
Uniform Statewide Building Code (VUSBC), which typically references a 115 mph baseline for
structural integrity.
6. Which type of solar thermal system uses a pump to circulate a heat-transfer fluid
through the collectors?
A. Passive (Thermosyphon)
B. Integral Collector Storage (ICS)
C. Active System
D. Gravity-fed System
Answer: C. Rationale: Active systems utilize mechanical pumps and electronic controllers to
move fluids, whereas passive systems rely solely on natural convection and gravity.
7. A "Grid-Tied" system without battery backup will behave how during a utility power
outage?
A. It will continue to power the house.
B. It will shut down immediately (Anti-islanding).
C. It will feed power back into the grid to help utility workers.
D. It will switch to DC mode for the lights.
Answer: B. Rationale: Standard grid-tied inverters must shut down during an outage to prevent
"islanding," which could electrocute utility workers attempting to repair the power lines.
, 2026 UPDATED QUESTIONS DOWNLOAD
8. The "Tilt Angle" of a fixed solar array in Virginia is ideally set to match:
A. The time of day.
B. The local latitude (approx. 37°–39°).
C. The height of the nearest tree.
D. 90 degrees.
Answer: B. Rationale: Setting the tilt to the local latitude maximizes the annual energy
production for a fixed-mount system by aligning with the average sun position throughout the
year.
9. "Net Metering" allows a Virginia customer to:
A. Get free electricity from the government.
B. Receive credit on their utility bill for excess energy sent back to the grid.
C. Only use solar power at night.
D. Connect their panels to the neighbor's house for sharing.
Answer: B. Rationale: Net metering tracks the "net" difference between what the customer
produces and what they consume, essentially using the grid as a virtual battery.
10. What is the purpose of a "Charge Controller" in a system with battery storage?
A. To turn the wind turbine faster.
B. To prevent batteries from overcharging and being damaged.
C. To clean the biomass fuel.
D. To measure the temperature of the inverter.
Answer: B. Rationale: The charge controller regulates the voltage and current coming from the
PV or wind source to ensure the battery bank remains at a safe state of charge.
11. Which NEC Article specifically covers Solar Photovoltaic (PV) Systems?
A. Article 250
B. Article 430
C. Article 690
D. Article 702
Answer: C. Rationale: NEC Article 690 is dedicated to the unique wiring, grounding, and
disconnecting requirements of PV systems.
12. "Azimuth" refers to what in a solar installation?
A. The angle of the sun above the horizon.
B. The compass direction the panels face (e.g., 180° for True South).
C. The weight of the panel per square foot.
D. The efficiency rating of the cells.
Answer: B. Rationale: For maximum production in the Northern Hemisphere, the ideal azimuth
is 180 degrees (True South) to capture the most sunlight.
13. A "Combiner Box" is used to:
A. Mix biomass fuel types.
B. Aggregate multiple PV strings into a single set of larger output conductors.
, 2026 UPDATED QUESTIONS DOWNLOAD
C. Store spare fuses.
D. Convert AC power back into DC power.
Answer: B. Rationale: It brings together the parallel wiring of multiple solar rows (strings) into
one output going to the inverter or charge controller.
14. What color is the insulation for a "Grounding Electrode Conductor" in an AES
system?
A. Red
B. Black
C. Green or Bare
D. White
Answer: C. Rationale: Per NEC standards, green insulation or bare copper is used for
grounding to identify it as a safety path for fault currents.
15. "Irradiance" is measured in which of the following units?
A. Volts per square inch.
B. Watts per square meter (
).
C. Amps per hour.
D. Pounds per square foot.
Answer: B. Rationale: Irradiance is the measurement of the power of sunlight (radiant flux)
hitting a specific surface area.
16. Fall protection is required in Virginia when working on a roof or surface higher than:
A. 4 feet
B. 6 feet
C. 10 feet
D. 12 feet
Answer: B. Rationale: OSHA and Virginia state safety standards generally require fall
protection (harnesses, guardrails) for any work performed at heights of 6 feet or more.
17. A "Governor" on a wind turbine is used to prevent:
A. The turbine from starting.
B. Overspeeding in high wind conditions.
C. The blades from turning at night.
D. Theft of the turbine.
Answer: B. Rationale: A governor (or braking system) slows the blades during high winds to
prevent mechanical failure or overheating of the generator.
18. In biomass energy, a "Gasifier" converts solid organic matter into:
A. Liquid gasoline.
B. Syngas (Synthetic Gas).
