Free PVSI Practice Questions

Question 1

A dwelling's rooftop array is tested under the 2017 NEC rapid-shutdown provisions, including the inside-array voltage-limiting method effective in 2019. At 25 seconds after initiation, the highest readings are 24 V outside the array boundary and 68 V inside it. These are the maxima across all required conductor-to-conductor and conductor-to-ground measurements, and they remain stable. How should these results be interpreted?

Accepted Answer

Both locations satisfy their applicable rapid-shutdown voltage and time limits.

Answer

Fail the inside-array result; the 30 V limit also applies there.

Answer

Treat both circuits as de-energized because all readings are below 80 V.

Answer

The test must be repeated at 10 seconds because the permitted shutdown interval was exceeded.

Question 2

The total ballast on a commercial rooftop array matches the approved design. However, the design calls for 60 lb in each corner tray and 30 lb in each interior tray, while one corner tray contains 30 lb and one interior tray contains 60 lb. The contractor argues that the unchanged total weight makes the arrangement equivalent. The installation should be brought into conformance by:

Accepted Answer

Restoring both tray weights to their locations in the approved ballast schedule.

Answer

Leaving the distribution unchanged because total ballast determines wind-uplift resistance.

Answer

Spreading the heavier tray's ballast among adjacent trays to equalize loading on the roof.

Answer

Adding ballast to the deficient corner while retaining the extra ballast in the interior tray.

Question 3

An MPPT charge controller receives 96 V at 12 A from an array and delivers 54 V at 20 A toward a battery bank during steady charging. Independent measurements confirm the current directions and values. No other charger is connected, and all readings are within the equipment's operating limits. What explains the higher battery-side current?

Accepted Answer

DC-to-DC conversion reduces voltage while increasing the available charging current.

Answer

The battery is backfeeding the array through failed blocking protection.

Answer

Battery overcharging caused by loss of the controller's output-current regulation.

Answer

The controller has bypassed conversion and directly connected array to battery.

Question 4

A panelboard has a 200 A bus and a 175 A main breaker at its upper end. A proposed inverter has a maximum continuous AC output of 48 A and a 60 A source breaker at the opposite end. The bus contains loads, the required source-location warning will be installed, and no other source is connected. Which calculation correctly evaluates the busbar limit under the 2017 NEC opposite-end 120% method?

Accepted Answer

175 A + (1.25 × 48 A) = 235 A, which is below 120% of the 200 A bus rating and passes.

Answer

200 A + 60 A = 260 A, which exceeds the 240 A allowance and fails the busbar check.

Answer

175 A + 60 A = 235 A, which exceeds 120% of the 175 A main-breaker rating and fails.

Answer

175 A + 48 A = 223 A, which passes because the source-current multiplier is unnecessary.

Question 5

A permit reviewer must establish the longest permissible series string for an inverter with a 600 V absolute DC-input limit and a 250-550 V MPPT operating range. Each module has Voc = 41.0 V at 25°C and a Voc temperature coefficient of −0.30%/°C. The accepted minimum design temperature for the Voc calculation is −10°C. Calculated module Vmp ranges from 28.0 V at the hot design condition to 38.0 V at the cold condition. Manufacturer instructions require use of the temperature coefficient; all other input limits are satisfied. What is the largest permissible number of modules in one string?

Accepted Answer

13 modules

Answer

12 modules

Answer

14 modules

Answer

15 modules

Question 6

A qualified thermographer examines a commercial inverter's three AC phase terminations under steady load. One lug measures 82°C; the other two measure 44°C and 45°C. Temperature drops rapidly along the conductor away from the hot lug. Phase currents are equal and within ratings. Conductor sizing, ambient conditions, and measurement emissivity have been checked. Which condition best fits this pattern?

Accepted Answer

Excessive contact resistance at the conductor-to-lug interface.

Answer

An undersized conductor set for the three-phase load.

Answer

Unequal loading of the inverter's three phases requiring load redistribution.

Answer

Cabinet air temperature exceeding the equipment's permitted operating range.

Question 7

An inspection photograph shows a PV roof mount with its metal flashing laid over the uphill asphalt shingles. A continuous bead of sealant covers the flashing's exposed upslope edge, and the roof deck is dry. The mount manufacturer's detail requires shingle-lapped flashing. Which correction addresses the water-shedding defect?

Accepted Answer

Reinstall the flashing with its upslope edge beneath the uphill shingle course.

Answer

Extend the flashing downslope without changing its sealed upper overlap.

Answer

Seal every exposed flashing edge to prevent water from entering.

Answer

Replace the sealant with roofing cement, leaving the shingles undisturbed.

Question 8

An installer proposes placing valve-regulated AGM batteries in a sealed, unventilated cabinet, arguing that the batteries recombine charging gases and are labeled 'sealed.' Which fact prevents that label alone from establishing the cabinet's suitability?

Accepted Answer

AGM batteries can vent gas; applicable ventilation requirements still must be met.

Answer

AGM batteries require flooded-battery equalization to prevent electrolyte stratification.

Answer

AGM batteries need removable vent caps so water lost during charging can be replaced.

Answer

AGM batteries release the same quantity of gas as flooded batteries at every charging rate.

Question 9

Three identical PV strings feed a combiner output circuit. Each string has a module-rated short-circuit current of 9.2 A. The circuit has 75°C terminals and 90°C-insulated copper conductors. The applicable combined ampacity correction and adjustment factor is 0.58. Copper table ampacities at 75°C/90°C are: 10 AWG, 35/40 A; 8 AWG, 50/55 A; 6 AWG, 65/75 A; and 4 AWG, 85/95 A. No alternative engineered-current calculation or 100%-rated assembly exception applies. Which is the smallest conductor that satisfies both 2017 NEC 690.8 ampacity checks?

Accepted Answer

6 AWG copper

Answer

10 AWG copper

Answer

8 AWG copper

Answer

4 AWG copper

Question 10

Choose the report entry that accurately describes this finding: The permit equipment schedule identifies one inverter model, but a different model is installed. Its listing, electrical ratings, protective functions, and required clearances have been verified as compliant. The substitution has not been approved through the local permit process.

Accepted Answer

Unresolved design deviation: the installed model lacks approval as a permit substitution.

Answer

Confirmed code violation: the replacement inverter's listing is invalid.

Answer

No inspection deficiency: equivalent electrical ratings automatically satisfy the approved permit.

Answer

Documentation complete: the installer's handwritten as-built note alone authorizes the substitution.

Free PVSI Practice Questions

Domain 1: Inspecting Electrical Components and Systems 44% of exam

Question 1

Question 2

Question 3

Question 4

Domain 2: Inspecting Energy Storage Components and Systems 21% of exam

Question 5

Question 6

Domain 3: Inspecting Mechanical/Structural Components and Systems 21% of exam

Question 7

Question 8

Domain 4: Documentation for the System Inspection 14% of exam

Question 9

Question 10

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