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Free PVDS Practice Questions

10 free, exam-style PV Design Specialist (PVDS) practice questions with answers and explanations. No signup required. Work through them below, then take the full free PVDS practice test to study every exam domain.

Question 1

A grid-tied PV array uses a string inverter with a 600 V maximum DC input. Which condition determines the MAXIMUM number of modules allowed in a series string?

  1. The highest expected ambient temperature, since heat is the harshest stress on the modules
  2. The lowest expected ambient temperature, since module voltage rises as it gets colder
  3. Standard Test Conditions of 25 °C, since that is the module's rated nameplate voltage
  4. The average annual site temperature, since it best reflects normal operating voltage
Show answer & explanation

Correct answer: B - The lowest expected ambient temperature, since module voltage rises as it gets colder

Question 2

A PV module is rated Isc = 10.0 A. The source-circuit conductor needs no temperature or conduit-fill derating. Per NEC 690.8, what minimum conductor ampacity is required using the no-correction-factor method?

  1. 10.0 A (the rated short-circuit current is used directly)
  2. 12.5 A (apply the 125% irradiance factor a single time)
  3. 15.6 A (apply the 125% factor twice: 10 x 1.25 x 1.25)
  4. 18.0 A (apply 125% then add a 15% rooftop allowance)
Show answer & explanation

Correct answer: C - 15.6 A (apply the 125% factor twice: 10 x 1.25 x 1.25)

Question 3

An existing 200 A busbar is fed by a 200 A main breaker. Using the NEC 705.12 120% rule for a load-side PV connection, what is the LARGEST back-fed PV breaker that may be installed?

  1. 20 A (the busbar's spare capacity is half of the main's rating)
  2. 40 A (120% of 200 A is 240 A, leaving 40 A above the main)
  3. 60 A (120% of the main breaker, then halved for safety)
  4. 100 A (a back-fed breaker may equal half the busbar rating)
Show answer & explanation

Correct answer: B - 40 A (120% of 200 A is 240 A, leaving 40 A above the main)

Question 4

A site assessor faces the proposed array and reads 188° on a magnetic compass. The local magnetic declination is 8° East. What is the TRUE azimuth the array faces?

  1. 172° (subtract twice the declination from the reading)
  2. 196° (add the east declination to the magnetic reading)
  3. 184° (split the declination evenly across the reading)
  4. 180° (assume the array faces due solar south by default)
Show answer & explanation

Correct answer: B - 196° (add the east declination to the magnetic reading)

Question 5

A site report lists '5.5 peak sun hours' for a location. What does this value represent for production estimating?

  1. The total number of hours per day that the sun is physically above the horizon
  2. The daily window during which the array stays completely free of any shading
  3. The peak instantaneous power the array can produce at solar noon on a clear day
  4. The equivalent hours per day of irradiance at the 1,000 W/m² reference level
Show answer & explanation

Correct answer: D - The equivalent hours per day of irradiance at the 1,000 W/m² reference level

Question 6

On a coastal home in a high-wind region, which load most often governs the spacing and quantity of structural roof attachments for a flush-mounted array?

  1. Dead load, the fixed downward weight of the modules, rails, and attachment hardware
  2. Live load, from technicians walking across the array during routine maintenance
  3. Wind uplift load, the suction force that lifts the array off the roof
  4. Thermal load, from daily expansion and contraction of the rails
Show answer & explanation

Correct answer: C - Wind uplift load, the suction force that lifts the array off the roof

Question 7

A ground-mount row rises 4 ft vertically from its lowest to highest edge. When the sun's altitude angle is 20°, the shadow it casts that the next row must clear is approximately (shadow = height ÷ tan θ):

  1. 1.5 ft (multiply the row height by the tangent of the angle)
  2. 4 ft (the shadow equals the vertical height of the row)
  3. 11 ft (divide the height by tan 20°, which is about 0.36)
  4. 20 ft (multiply the height by the sun's altitude in degrees)
Show answer & explanation

Correct answer: C - 11 ft (divide the height by tan 20°, which is about 0.36)

Question 8

A homeowner's top priority is keeping the refrigerator and some lights running during utility outages. A standard grid-tied PV system on its own will NOT meet this need because:

  1. Grid-tied inverters shut down in an outage to avoid energizing utility lines
  2. PV modules stop producing power on the cloudy days when outages happen
  3. Net-metering credits are automatically suspended whenever the grid drops
  4. The utility requires the AC disconnect to stay open during any disturbance
Show answer & explanation

Correct answer: A - Grid-tied inverters shut down in an outage to avoid energizing utility lines

Question 9

When selecting exposed PV source-circuit conductors (such as PV Wire or USE-2) on a rooftop, the NEC requires the conductor insulation to be rated for which minimum temperature?

  1. 60 °C, the default ampacity column used for most general-purpose building wiring
  2. 75 °C, chosen to match the equipment terminal temperature rating at the inverter
  3. 90 °C, because PV source-circuit conductors face the hot rooftop environment
  4. 105 °C, the elevated insulation rating normally reserved for service conductors
Show answer & explanation

Correct answer: C - 90 °C, because PV source-circuit conductors face the hot rooftop environment

Question 10

A customer wants the monitoring system to detect underperformance of any single module, such as soiling or a failing cell. Which monitoring approach is REQUIRED to meet that goal?

  1. System-level monitoring of total AC output measured at the inverter terminals
  2. Utility revenue-meter readings compared against the monthly utility bill totals
  3. String-level monitoring taken at each combiner-box input feeding the inverter
  4. Module-level monitoring, as provided by microinverters or power optimizers
Show answer & explanation

Correct answer: D - Module-level monitoring, as provided by microinverters or power optimizers

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