NABCEP PV Installation Professional (PVIP) Certification Exam — Questions and Answers

Question 1: Per NEC Article 694, what type of disconnecting means is required for utility-interactive small wind systems?

A circuit breaker located exclusively inside the main service panel
A locked disconnect accessible only to the certified installer
An accessible, load-break rated disconnecting means that utility personnel can operate (Correct answer)
A fused knife switch rated for DC current only

Correct answer: An accessible, load-break rated disconnecting means that utility personnel can operate

NEC 694.22 requires an accessible, load-break rated disconnecting means so that utility personnel can safely de-energize the wind system from the utility side.

Question 2: What is the function of a differential controller in an active solar thermal system?

It controls the backup electric heater only
It converts DC power to AC for the pump
It measures solar irradiance only
It turns the circulator pump on when the collector is hotter than the storage tank and off when it is not (Correct answer)

Correct answer: It turns the circulator pump on when the collector is hotter than the storage tank and off when it is not

The differential controller compares temperatures at the collector and storage tank and activates the pump when the collector temperature exceeds the tank by a set threshold, preventing reverse circulation.

Question 3: When sizing a battery storage system for self-consumption optimization, what load data is most critical?

The nameplate rating of the largest appliance
Utility company's peak demand time only
Annual average daily kWh usage
Historical hourly load profile of the facility (Correct answer)

Correct answer: Historical hourly load profile of the facility

Hourly load profile data reveals when energy demand peaks and troughs throughout the day, enabling accurate sizing of battery capacity to maximize self-consumption.

Question 4: What does 'capacity factor' mean for a wind turbine installation?

The turbine's maximum rated power output
The turbine blade's structural safety factor
The number of hours per year the turbine operates
The ratio of actual annual energy produced to the theoretical maximum if the turbine ran at full rated power all year (Correct answer)

Correct answer: The ratio of actual annual energy produced to the theoretical maximum if the turbine ran at full rated power all year

Capacity factor compares actual output to the theoretical maximum, reflecting how well real-world wind conditions utilize the turbine's full capacity; US land-based wind typically achieves 25–45%.

Question 5: When inspecting a battery energy storage system added to an existing PV system, which code document governs the installation requirements?

Only the battery manufacturer's manual
Both NEC 706 (energy storage) and NFPA 855, in addition to NEC 690 for the PV portions (Correct answer)
NEC 690 only
Only local building code, not NEC

Correct answer: Both NEC 706 (energy storage) and NFPA 855, in addition to NEC 690 for the PV portions

ESS installations must comply with NEC 706 for electrical requirements, NFPA 855 for fire and life safety, and NEC 690 for PV interconnection portions.

Question 6: A battery storage system is set to 'time-of-use' (TOU) mode. What does this mean operationally?

The battery charges during low-rate periods and discharges during high-rate periods to reduce utility costs (Correct answer)
The battery exports power to the grid at all times
The battery only operates during nighttime hours
The battery charges and discharges randomly

Correct answer: The battery charges during low-rate periods and discharges during high-rate periods to reduce utility costs

TOU optimization charges the battery when electricity rates are low (typically off-peak) and discharges it when rates are high (on-peak), reducing the customer's electricity bill.

Question 7: An inspector observes PV modules installed on a roof without any visible rapid shutdown equipment. The system is on a building in a jurisdiction that has adopted NEC 2017 or later. Is this a code violation?

Yes, NEC 690.12 requires rapid shutdown for PV systems on buildings under NEC 2017 and later (Correct answer)
Yes, but only for commercial buildings over 3 stories
No, rapid shutdown is optional for residential systems
No, if the inverter is outside the building

Correct answer: Yes, NEC 690.12 requires rapid shutdown for PV systems on buildings under NEC 2017 and later

NEC 690.12 (2017 and later) requires rapid shutdown for all PV systems installed on buildings, regardless of occupancy type, to protect emergency responders.

Question 8: When designing a PV system, why is it important to consider the azimuth angle?

It influences the amount of solar radiation the modules will receive (Correct answer)
It determines the length of the solar array
It affects the system's exposure to wind
It impacts the thermal management of the system

Correct answer: It influences the amount of solar radiation the modules will receive

Higher operating temperatures significantly decrease the efficiency of PV modules. As the temperature of the solar cells rises, their voltage output drops, leading to a reduction in overall power production. This phenomenon highlights the importance of proper ventilation and cooling considerations in PV system design to maintain optimal performance and energy yield.

Question 9: What is the inspector checking when verifying the 'AC disconnect within sight of the inverter' requirement?

That the disconnect is within 50 feet of the inverter
That the disconnect is on the same wall as the inverter
That the utility meter is within sight of the inverter
That a listed disconnect means is installed within sight of (visible from and within 50 feet of) the inverter per NEC 690.15 (Correct answer)

Correct answer: That a listed disconnect means is installed within sight of (visible from and within 50 feet of) the inverter per NEC 690.15

NEC 690.15 requires a means to disconnect the inverter from all ungrounded conductors within sight of the inverter, defined as visible and within 50 feet, to allow safe servicing.

Question 10: In the context of PV system warranties, what does the term "performance warranty" typically refer to?

The guarantee of the system's energy production over a specified period (Correct answer)
The insurance coverage for weather-related damage
The warranty on the physical components of the PV system
The warranty on the installation workmanship

Correct answer: The guarantee of the system's energy production over a specified period

Net metering is a billing mechanism that credits solar energy system owners for the excess electricity they generate and feed back into the utility grid. When a residential PV system produces more electricity than the home consumes, the surplus is sent to the grid, and the homeowner receives credits on their electricity bill. This incentivizes solar adoption by effectively allowing homeowners to 'store' excess generation with the utility.

Question 11: A small wind turbine produces three-phase AC output at variable frequency. What conversion process makes this output compatible with the utility grid?

A battery charge controller regulates the output before grid connection
A synchronous condenser synchronizes the turbine output to grid frequency
The variable AC is rectified to DC, then inverted to 60 Hz AC by a grid-tie inverter (Correct answer)
A step-up transformer directly converts the variable frequency to grid frequency

Correct answer: The variable AC is rectified to DC, then inverted to 60 Hz AC by a grid-tie inverter

Variable-frequency AC from the turbine is first converted to DC by a rectifier, then the DC is converted to stable 60 Hz AC by a grid-tie inverter for utility connection.

Question 12: What is a wind shadow (turbulence zone) that forms downwind of an obstruction such as a building or tree line?

A zone of reduced and turbulent airflow extending 10–20 times the height of the obstruction downwind (Correct answer)
A region of accelerated wind speed behind the obstacle
An area where ice accumulates on turbine blades
A zone where wind changes direction by more than 45 degrees

Correct answer: A zone of reduced and turbulent airflow extending 10–20 times the height of the obstruction downwind

Obstacles create a turbulent wake zone extending 10–20 times their height downwind, which degrades energy output and increases mechanical fatigue on turbines sited within it.

Question 13: Why is it important to consider local building codes and regulations when designing a PV system?

To reduce the number of PV modules needed
To ensure the system is aesthetically pleasing
To increase the cost of the system
To avoid penalties and ensure the safety and compliance of the installation (Correct answer)

Correct answer: To avoid penalties and ensure the safety and compliance of the installation

The initial and most crucial step in the PV sales process is to thoroughly understand the customer's energy needs and goals. This involves discussing their current electricity consumption, financial objectives, environmental motivations, and any specific requirements they may have. This foundational understanding allows the salesperson to tailor a customized solution that truly meets the customer's expectations and builds trust.

Question 14: What sizing tool does SRCC and the solar industry use to estimate annual solar water heating system performance by location?

RETScreen energy analysis
F-Chart method or Solar Rating and Certification Corporation OG-300 simulation (Correct answer)
ASHRAE load calculator
Manual J residential load calculation

Correct answer: F-Chart method or Solar Rating and Certification Corporation OG-300 simulation

The F-Chart method is the industry standard analytical tool for estimating the annual solar fraction and performance of solar water heating systems using local climate data.

Question 15: Which NEC article primarily governs the installation and maintenance safety requirements for PV systems in the US?

NEC Article 480
NEC Article 310
NEC Article 690 (Correct answer)
NEC Article 230

Correct answer: NEC Article 690

NEC Article 690 specifically addresses solar photovoltaic systems, covering wiring, disconnects, overcurrent protection, and safety requirements.

Question 16: Which heat transfer fluid is commonly used in closed-loop solar thermal systems to prevent freezing?

Propylene glycol-water mixture (Correct answer)
Gasoline
Distilled water only
Ammonia

Correct answer: Propylene glycol-water mixture

Propylene glycol mixed with water is the standard non-toxic antifreeze heat transfer fluid for closed-loop solar thermal systems, providing freeze protection without plumbing contamination risk.

Question 17: What is the primary purpose of a net metering agreement for residential PV systems?

To reduce the installation cost
To monitor the performance of the PV system
To allow the homeowner to sell excess electricity back to the grid (Correct answer)
To provide maintenance services for the PV system

Correct answer: To allow the homeowner to sell excess electricity back to the grid

A comprehensive PV system proposal should provide a clear and transparent overview for the potential customer, enabling them to make an informed decision. It must include a detailed breakdown of components, a visual representation of the system design, a clear cost structure, and realistic projections of expected energy savings and financial benefits. This holistic approach builds trust and demonstrates the full value proposition.

Question 18: What is the purpose of a dump load (diversion load) in a battery-based small wind system?

To convert AC turbine output to DC for battery charging
To dissipate excess energy when the battery bank is fully charged (Correct answer)
To start the turbine during low-wind conditions
To measure and log system energy production

Correct answer: To dissipate excess energy when the battery bank is fully charged

A dump load absorbs surplus energy when batteries reach full state of charge, preventing overvoltage that would damage the battery bank and other components.

Question 19: n PV system design, what is the significance of the system's "derate factor"?

It estimates the loss in system performance due to inefficiencies (Correct answer)
It determines the lifespan of the PV modules
It calculates the total cost of the system
It measures the aesthetic appeal of the installation

Correct answer: It estimates the loss in system performance due to inefficiencies

Considering local building codes and regulations is paramount when designing a PV system to ensure the installation is safe, compliant, and avoids legal penalties. These codes dictate structural requirements, electrical standards, and permitting processes, all of which are essential for the system's integrity and long-term operation. Adherence guarantees the system meets minimum safety and quality standards.

Question 20: What does the inspector verify when checking the PV system's grounding and bonding?

That all modules are grounded to the roof structure only
That all equipment is bonded to a common grounding electrode system per NEC Article 250 and 690 (Correct answer)
That the DC negative conductor serves as the grounding conductor
That only the inverter is grounded

Correct answer: That all equipment is bonded to a common grounding electrode system per NEC Article 250 and 690

NEC requires all metallic equipment, racking, and enclosures to be bonded together and connected to a grounding electrode system that meets both Article 250 and Article 690 requirements.

Question 21: What is the recommended method for detecting hot spots in PV modules during a maintenance inspection?

Infrared (IR) thermography (Correct answer)
Clamp meter readings
Visual inspection only
Acoustic testing

Correct answer: Infrared (IR) thermography

Infrared thermography reveals thermal anomalies caused by cell cracks, bypass diode failures, or soiling that are invisible to the naked eye.

Question 22: Which building code section requires solar water heating systems to be installed with a means of preventing scalding from excessively hot water?

NEC Article 690
IBC structural section only
NFPA 72 fire alarm code
UPC/IPC Plumbing Code sections requiring a tempering or mixing valve on solar water heaters (Correct answer)

Correct answer: UPC/IPC Plumbing Code sections requiring a tempering or mixing valve on solar water heaters

Uniform Plumbing Code and International Plumbing Code require a thermostatic mixing (tempering) valve on solar water heaters because solar storage tanks are often set above 140°F to prevent Legionella.

Question 23: What is the typical warranty cycle life for a quality residential lithium-ion battery storage system?

500–1,000 cycles
4,000–6,000 cycles or more (Correct answer)
100 cycles
10 cycles per year

Correct answer: 4,000–6,000 cycles or more

Quality residential lithium-ion batteries (e.g., LFP chemistry) are typically warranted for 4,000–6,000+ cycles, translating to 10–15+ years of daily cycling.

Question 24: During maintenance, you discover arc marks inside an outdoor DC combiner box. What should you do first?

Replace the combiner box cover only
De-energize the affected circuits and identify the cause before restoring power (Correct answer)
Log the finding for next year's inspection
Clean the marks and close the box

Correct answer: De-energize the affected circuits and identify the cause before restoring power

Arc marks indicate arcing has occurred, which is a fire and shock hazard; the affected circuits must be de-energized immediately and the root cause identified before restoring power.

Question 25: During a final PV system inspection, an inspector finds that the disconnect label reads 'AC Disconnect' but serves as both the AC disconnect and the rapid shutdown initiator. What should the inspector do?

Require correct labeling per NEC 690.13 and 690.12 identifying all functions of the disconnect (Correct answer)
Reject the entire installation
Require a separate disconnect for rapid shutdown only
Accept it because it still functions correctly

Correct answer: Require correct labeling per NEC 690.13 and 690.12 identifying all functions of the disconnect

NEC requires clear, accurate labeling on all disconnecting means to ensure safety personnel understand each device's function; a device serving multiple roles must be labeled for all of them.

Question 26: What type of heat exchanger is most commonly used in pressurized closed-loop solar thermal systems to protect potable water?

Direct open-loop coil
Single-wall copper coil submerged in the tank
Double-wall heat exchanger for separation of glycol from potable water (Correct answer)
Plate heat exchanger with no double-wall requirement

Correct answer: Double-wall heat exchanger for separation of glycol from potable water

Many plumbing codes require a double-wall heat exchanger when toxic antifreeze (or any non-potable fluid) transfers heat to a potable water supply, preventing contamination in case of failure.

Question 27: What document establishes the maximum allowable energy capacity of battery energy storage systems installed in residential occupancies?

UL 9540 Product Standard
NFPA 855 Standard for the Installation of Stationary Energy Storage Systems (Correct answer)
IBC Structural Code
NEC Article 690

Correct answer: NFPA 855 Standard for the Installation of Stationary Energy Storage Systems

NFPA 855 sets energy capacity limits, separation distances, and installation requirements specifically for stationary energy storage systems in all occupancy types including residential.

Question 28: Per the widely accepted '30-foot rule,' how much taller should a small wind turbine hub be above any obstruction within 500 feet of the installation?

50 feet
30 feet (Correct answer)
10 feet
20 feet

Correct answer: 30 feet

The 30-foot rule states a turbine hub should be at least 30 feet above any obstruction within 500 feet to avoid turbulent wake effects that reduce output and increase fatigue loads.

Question 29: Which labeling requirement applies to all energy storage system enclosures per NEC 706?

No labeling is required for residential systems
Only the manufacturer's logo is required
Labels identifying the system as an energy storage system and warning of shock hazard (Correct answer)
Labels are only required for commercial installations

Correct answer: Labels identifying the system as an energy storage system and warning of shock hazard

NEC 706 requires warning labels on ESS enclosures to alert first responders and service personnel to the presence of stored electrical energy and associated hazards.

Question 30: What maintenance task should be performed on PV module surfaces in dusty or arid climates more frequently than in other regions?

Updating monitoring firmware
Cleaning to remove soiling (Correct answer)
Replacing bypass diodes
Recabling

Correct answer: Cleaning to remove soiling

Dust and particulate buildup (soiling) reduces light transmission to PV cells and can significantly reduce energy output, requiring more frequent cleaning in arid climates.

Question 31: In a drainback solar thermal system, what prevents freeze damage when the pump shuts off?

The water drains back into an indoor reservoir by gravity when the pump stops (Correct answer)
Foam insulation on collectors only
Antifreeze glycol in the fluid
An electric heat trace on all outdoor pipes

Correct answer: The water drains back into an indoor reservoir by gravity when the pump stops

Drainback systems are designed so that water flows only when the pump is running; when the pump stops, gravity returns all water to an indoor reservoir, leaving no water in the collectors to freeze.

Question 32: What is the Solar Fraction (SF) of a solar thermal system?

The angle of the collector relative to true south
The percentage of the total heating load supplied by solar energy (Correct answer)
The system's thermal efficiency at standard test conditions
The ratio of collector area to storage volume

Correct answer: The percentage of the total heating load supplied by solar energy

Solar fraction represents the portion of a building's total water or space heating load that is met by the solar thermal system, with higher values indicating greater solar contribution.

Question 33: What is the annual energy production (AEP) calculation used for in wind project feasibility?

To estimate the total kWh the turbine will produce annually, used to evaluate economic viability and financial returns (Correct answer)
To size the inverter only
To calculate the tower's structural loading
To determine the turbine's noise level

Correct answer: To estimate the total kWh the turbine will produce annually, used to evaluate economic viability and financial returns

AEP combines the turbine's power curve with the site's wind speed distribution to estimate annual energy output in kWh, which is used to calculate revenue, payback, and return on investment.

Question 34: What is the primary consideration when selecting the orientation of PV modules in the Northern Hemisphere?

East
South (Correct answer)
North
West

Correct answer: South

The latitude of the installation site is the most crucial factor for determining the optimal tilt angle for fixed PV modules. Setting the tilt angle approximately equal to the latitude allows the modules to receive the most direct sunlight annually. This maximizes the amount of solar energy captured over the year, leading to optimal system performance.

Question 35: Which federal agency must be notified for wind turbine installations that exceed certain heights near airports or in navigable airspace?

FAA (Federal Aviation Administration) (Correct answer)
EPA (Environmental Protection Agency)
USDA (US Department of Agriculture)
FERC (Federal Energy Regulatory Commission)

Correct answer: FAA (Federal Aviation Administration)

The FAA requires notification (Form 7460-1) for structures that may affect navigable airspace, including wind turbines above certain heights, and may require aviation lighting on tall towers.

Question 36: What is the primary difference between a solar thermal collector and a photovoltaic (PV) module?

Solar thermal collectors require no maintenance
Solar thermal collectors generate electricity directly
Solar thermal collectors convert sunlight into heat, while PV modules convert sunlight into electricity (Correct answer)
PV modules produce more energy per square foot in all climates

Correct answer: Solar thermal collectors convert sunlight into heat, while PV modules convert sunlight into electricity

Solar thermal collectors capture solar radiation and transfer that energy as heat to a fluid, whereas PV modules use the photovoltaic effect to generate direct current electricity.

Question 37: An inspector observes that a rooftop PV system's equipment grounding conductors (EGCs) are connected using standard steel sheet metal screws into racking. Is this acceptable?

No, EGC bonding connections must use listed bonding hardware designed to penetrate anodized or painted surfaces and maintain a reliable connection (Correct answer)
Yes, as long as the screws are coated
Yes, any steel fastener is acceptable for bonding
Yes, for residential systems under 10 kW

Correct answer: No, EGC bonding connections must use listed bonding hardware designed to penetrate anodized or painted surfaces and maintain a reliable connection

Standard sheet metal screws do not reliably penetrate anodized aluminum or painted surfaces to make a code-compliant bond; listed bonding hardware (e.g., Weeb clips, bonding washers) must be used.

Question 38: Which instrument is the primary tool used to measure wind speed during a small wind site assessment?

Barometer
Hygrometer
Anemometer (Correct answer)
Pyranometer

Correct answer: Anemometer

An anemometer measures wind speed and is the standard instrument used in wind resource assessments to collect site data.

Question 39: What is 'stagnation' in a solar thermal system and why is it a concern?

When collectors are shaded for extended periods
When no fluid flows through the collectors while they are receiving full solar radiation, causing extreme temperatures and potential fluid degradation (Correct answer)
When the storage tank is fully charged
When the pump runs continuously without stopping

Correct answer: When no fluid flows through the collectors while they are receiving full solar radiation, causing extreme temperatures and potential fluid degradation

Stagnation occurs when circulation stops while collectors are in full sun, causing fluid temperatures to spike well above 300°F, which can degrade glycol, damage seals, and create steam.

Question 40: An inspector notes that the PV inverter is installed in a location where ambient temperature regularly exceeds the inverter's rated operating temperature range. What is the concern?

Higher temperatures improve inverter efficiency
The inverter will overproduce energy
The inverter will derate output or fail prematurely due to thermal stress, and is not installed per manufacturer specifications (Correct answer)
The inverter will charge the battery too fast

Correct answer: The inverter will derate output or fail prematurely due to thermal stress, and is not installed per manufacturer specifications

Inverters installed outside their rated ambient temperature range will derate power output or experience premature failure; installations must comply with manufacturer temperature specifications.

Question 41: What does an insulation resistance test (megohm test) during commissioning detect?

Inverter efficiency
Ground faults or damaged insulation in wiring (Correct answer)
Battery state of charge
Module power output degradation

Correct answer: Ground faults or damaged insulation in wiring

A megohm test applies high voltage to conductors to detect insulation breakdowns or ground faults that could cause safety hazards.

Question 42: What wire gauge and color coding issue is a common code violation found during PV system inspections?

Using white or gray conductors for ungrounded DC positive conductors without marking them with the correct polarity color (Correct answer)
Using conduit instead of raceways
Using aluminum conductors for branch circuits
Using copper conductors for DC circuits

Correct answer: Using white or gray conductors for ungrounded DC positive conductors without marking them with the correct polarity color

NEC 690.31(B) requires that conductors not of the required color be permanently re-identified with colored tape, paint, or marking at each end; white conductors used as positive DC conductors must be re-marked.

Question 43: During an inspection, a roof-mounted PV system has modules installed with less than the required setback from the roof edge. What code is most likely violated?

NEC 690.12 rapid shutdown
IFC 605.11 or equivalent local fire code requiring access pathways and setbacks for firefighter access (Correct answer)
NFPA 70E arc flash standard
NEC 690.4 general installation

Correct answer: IFC 605.11 or equivalent local fire code requiring access pathways and setbacks for firefighter access

International Fire Code and local fire codes specify minimum setbacks from roof edges, ridges, and hips to ensure firefighter access and ventilation paths on residential roofs.

Question 44: What is the primary hazard when performing maintenance on a PV array that cannot be fully de-energized by shutting off the inverter?

Low voltage shock risk from AC circuits
PV modules continue to produce DC voltage in daylight even with the inverter off (Correct answer)
Loss of monitoring data
Module glass cracking from thermal stress

Correct answer: PV modules continue to produce DC voltage in daylight even with the inverter off

PV modules generate DC voltage whenever light hits them, so DC conductors remain energized even when the inverter and AC breakers are off, posing a shock hazard.

Question 45: At what reference wind speed are small wind turbines typically rated for power output per IEC 61400-2 and AWEA standards?

35 mph (15.6 m/s)
8 mph (3.5 m/s)
11 mph (4.9 m/s)
24.6 mph (11 m/s) (Correct answer)

Correct answer: 24.6 mph (11 m/s)

Small wind turbines are rated at a reference wind speed of 11 m/s (approximately 24.6 mph) to provide a standardized basis for comparing turbine performance.

Question 46: Which federal resource provides publicly available wind resource maps for the contiguous United States?

FAA sectional aeronautical charts
NREL Wind Prospector / Wind Resource Maps (Correct answer)
NOAA hurricane track database
USGS topographic database

Correct answer: NREL Wind Prospector / Wind Resource Maps

NREL's Wind Prospector and associated Wind Resource Maps provide publicly accessible modeled wind speed data at various heights across the US to support wind project siting.

Question 47: Which interconnection mode allows a battery storage system to power critical loads during a grid outage?

Islanding or backup mode (Correct answer)
Grid-tied only mode
Export-only mode
Net metering mode

Correct answer: Islanding or backup mode

Islanding or backup mode allows the storage system to disconnect from the grid and power a critical loads panel independently during outages.

Question 48: What is the purpose of verifying the PV system's maximum system voltage during an inspection?

To confirm that all system components (wiring, inverters, disconnects, modules) are rated for the maximum DC voltage the system can produce (Correct answer)
To ensure the utility will accept the interconnection
To calculate the system's payback period
To determine the number of modules per string

Correct answer: To confirm that all system components (wiring, inverters, disconnects, modules) are rated for the maximum DC voltage the system can produce

Maximum system voltage (calculated under lowest expected temperature conditions) must not exceed the voltage rating of any component; exceeding ratings risks insulation failure, fire, or equipment damage.

Question 49: What is the primary advantage of a closed-loop solar thermal system over an open-loop system?

It is always less expensive to install
It requires no expansion tank
It operates without a heat exchanger
It protects the collector loop from freezing and corrosion while keeping potable water separate (Correct answer)

Correct answer: It protects the collector loop from freezing and corrosion while keeping potable water separate

Closed-loop systems use antifreeze in a separate loop, providing freeze protection and preventing mineral scale buildup in expensive collectors while maintaining potable water purity.

Question 50: Which installation orientation and tilt maximizes annual solar thermal energy collection in the continental US?

Due west at 45°
True south at a tilt angle approximately equal to the local latitude (Correct answer)
Due east at 90°
Horizontal (0° tilt) facing any direction

Correct answer: True south at a tilt angle approximately equal to the local latitude

Facing collectors true south and tilting them at the local latitude angle maximizes annual solar irradiance interception across all seasons in the Northern Hemisphere.

Question 51: What grounding requirement applies to metal towers used for small wind turbines?

Towers must be bonded to the turbine DC negative terminal only
Towers must be connected to the system equipment grounding conductor (Correct answer)
Grounding is optional when the tower is installed on a non-conductive foundation
Towers require separate lightning rod protection but no equipment grounding

Correct answer: Towers must be connected to the system equipment grounding conductor

Metal towers must be bonded to the equipment grounding system so that a fault will trip overcurrent protection rather than energize the tower structure.

Question 52: What is a thermosiphon solar water heating system and where is it commonly used?

A system that requires a differential controller to operate
A system using glycol under high pressure
A passive system where natural convection circulates fluid; common in mild climates with no freeze risk (Correct answer)
A system using an electric pump driven by PV modules

Correct answer: A passive system where natural convection circulates fluid; common in mild climates with no freeze risk

Thermosiphon systems use natural convection — hot fluid rises into the storage tank above the collectors — eliminating pumps and controls; they are used in warm, freeze-free climates.

Question 53: What is the significance of the 'cut-in wind speed' of a wind turbine?

The speed at which the turbine must be shut down for safety
The turbine's peak efficiency wind speed
The average wind speed required for turbine installation
The minimum wind speed at which the turbine begins generating electricity (Correct answer)

Correct answer: The minimum wind speed at which the turbine begins generating electricity

Cut-in wind speed is the minimum wind speed at which the rotor generates enough torque for the generator to produce useful electricity; below this speed the turbine is idle.

Question 54: A monitoring system shows a sudden 20% drop in a single string's output on a clear day. Which maintenance action is most appropriate?

Inspect that string for a shaded, disconnected, or failed module (Correct answer)
Add a new string to compensate
Wait one month and compare again
Reduce the inverter's power limit

Correct answer: Inspect that string for a shaded, disconnected, or failed module

A sudden output drop in one string on a clear day indicates a localized fault — a shaded, disconnected, or failed module — that warrants immediate physical inspection.

Question 55: What is the purpose of a pressure relief valve in a solar thermal system?

To release excess pressure and prevent damage to collectors or storage tanks from thermal expansion (Correct answer)
To regulate pump speed
To control collector tilt angle
To measure flow rate

Correct answer: To release excess pressure and prevent damage to collectors or storage tanks from thermal expansion

Thermal expansion during stagnation (when the pump is off but collectors are hot) can create very high pressures, and the relief valve opens to prevent system damage or rupture.

Question 56: During the installation of a PV system, what is the purpose of grounding the PV array?

To prevent electrical shock and protect against lightning (Correct answer)
To improve energy efficiency
To enhance the performance of the PV modules
To reduce the cost of installation

Correct answer: To prevent electrical shock and protect against lightning

Grounding the PV array is a critical safety measure that provides a safe path for fault currents to dissipate into the earth. This prevents dangerous electrical shocks to personnel who might come into contact with the system. Additionally, grounding protects the PV system components from damage caused by high voltage surges, such as those from lightning strikes, by diverting the energy safely away.

Question 57: Which of the following best defines 'capacity factor' as applied to a small wind turbine?

The ratio of actual annual energy produced to the theoretical maximum energy if the turbine operated at rated power continuously (Correct answer)
The ratio of turbine rotor diameter to hub height
The maximum wind speed at which the turbine can safely generate power
The percentage of calendar time the turbine is mechanically available to operate

Correct answer: The ratio of actual annual energy produced to the theoretical maximum energy if the turbine operated at rated power continuously

Capacity factor compares actual annual energy output to what the turbine would produce if it ran at full rated power every hour of the year; small wind turbines typically achieve 20–35%.

Question 58: What is the minimum required clearance around battery energy storage systems for maintenance access per NFPA 855?

6 inches on all sides
No clearance required if enclosed
12 inches top clearance only
36 inches on service side, per equipment labeling and local AHJ requirements (Correct answer)

Correct answer: 36 inches on service side, per equipment labeling and local AHJ requirements

NFPA 855 requires adequate maintenance clearance, typically 36 inches on the service side, consistent with other electrical equipment requirements and as specified by the AHJ.

Question 59: What must an inspector verify regarding the PV system's interconnection with the utility service panel to ensure NEC 705 compliance?

The sum of breaker ampere ratings on a busbar does not exceed 120% of the busbar's ampere rating (120% rule) when the solar breaker is at the opposite end from the main breaker (Correct answer)
The interconnection breaker is at least 200A
The solar breaker is adjacent to the main breaker
No additional breaker verification is required

Correct answer: The sum of breaker ampere ratings on a busbar does not exceed 120% of the busbar's ampere rating (120% rule) when the solar breaker is at the opposite end from the main breaker

NEC 705.12(B) allows the supply-side connection via the 120% rule: the sum of the main breaker and solar breaker must not exceed 120% of the busbar rating, and the solar breaker must be at the opposite end.

Question 60: An inspector finds the required PV system disconnecting means is not accessible without a ladder and is located 15 feet above finished grade on a commercial building wall. Is this compliant?

No, NEC 690.13 generally requires disconnects to be readily accessible and NEC 240.24 limits service disconnects to within 6.5 feet of finished grade unless exceptions apply (Correct answer)
No, all disconnects must be at ground level regardless of building type
Yes, commercial installations have no height restrictions
Yes, if the utility approves the location

Correct answer: No, NEC 690.13 generally requires disconnects to be readily accessible and NEC 240.24 limits service disconnects to within 6.5 feet of finished grade unless exceptions apply

Disconnecting means must be readily accessible per NEC, and heights above 6.5 feet are generally not considered readily accessible unless specific exceptions for qualified-person-only areas apply.

Question 61: A combiner box fuse blows repeatedly in the same string position. What is the most appropriate next step?

Bypass the fuse position
Increase the inverter's MPPT voltage range
Replace with a higher-rated fuse
Inspect the string for a ground fault or short circuit (Correct answer)

Correct answer: Inspect the string for a ground fault or short circuit

A repeatedly blown fuse indicates an underlying fault such as a ground fault or short circuit in that string, which must be identified and corrected before replacing the fuse.

Question 62: What does SRCC OG-300 certification indicate for a solar water heating system?

The system uses only certified PV modules
The complete solar water heating system has been rated and certified for annual energy performance (Correct answer)
The installer is NABCEP certified
The collector alone meets efficiency standards

Correct answer: The complete solar water heating system has been rated and certified for annual energy performance

SRCC OG-300 certifies the entire system — including collector, storage, and controls — and provides annual energy output estimates used for rebate qualification and consumer comparison.

Question 63: What is the purpose of a shading analysis during the design phase of a PV system?

To assess the thermal properties of the PV modules
To determine the optimal orientation of the system
To estimate the cost of the PV system
To identify potential obstructions that could reduce system performance (Correct answer)

Correct answer: To identify potential obstructions that could reduce system performance

The azimuth angle, which is the compass direction the PV modules face, is critical because it directly influences the amount of solar radiation the modules will receive throughout the day. Optimizing this angle, typically towards true south in the Northern Hemisphere, maximizes the system's exposure to sunlight. This ensures the highest possible energy production from the PV array.

Question 64: Which tool is essential for verifying PV string open-circuit voltage during commissioning?

Clamp meter
Power analyzer
Pyranometer
Digital multimeter (Correct answer)

Correct answer: Digital multimeter

A digital multimeter measures open-circuit voltage (Voc) of PV strings to confirm they are within expected ranges before connection.

Question 65: For a small wind system installed on a one- or two-family dwelling, what is the maximum system voltage permitted under NEC Article 694?

300 volts
1,000 volts
600 volts (Correct answer)
1,500 volts

Correct answer: 600 volts

NEC Article 694.7 limits small wind system voltage to 600V for one- and two-family dwelling units, consistent with similar voltage limits in other residential renewable energy articles.

Question 66: What is the primary function of a Battery Management System (BMS) in an energy storage installation?

Connect the battery to the PV array directly
Monitor and protect battery cells from overcharge, over-discharge, and thermal events (Correct answer)
Convert DC battery power to AC for the grid
Increase battery capacity over time

Correct answer: Monitor and protect battery cells from overcharge, over-discharge, and thermal events

The BMS continuously monitors cell voltages, temperatures, and state of charge to protect the battery from conditions that would damage it or create safety hazards.

Question 67: What is the recommended storage volume per unit collector area for a solar domestic water heating system?

Storage volume has no relationship to collector area
5 gallons per square foot of collector
1 gallon per square foot of collector
1.5–2 gallons per square foot of collector (Correct answer)

Correct answer: 1.5–2 gallons per square foot of collector

Industry guidelines recommend 1.5–2 gallons of storage per square foot of collector area to ensure adequate thermal mass without oversizing the tank to the point of poor solar fraction.

Question 68: Which factor is most important when determining the tilt angle for PV modules in a fixed-tilt system?

Wind speed in the area
Latitude of the installation site (Correct answer)
Module manufacturer
Roof color

Correct answer: Latitude of the installation site

A shading analysis is an essential step during the design phase of a PV system to identify any potential obstructions, such as trees, chimneys, or adjacent buildings, that might cast shadows on the PV array. Even partial shading can significantly reduce the output of an entire string of modules. By identifying and mitigating shading, designers can optimize module placement and predict accurate energy production.

Question 69: What is the purpose of a torque wrench during PV system maintenance?

To tighten electrical and mechanical connections to manufacturer-specified torque values (Correct answer)
To measure module efficiency
To cut conduit
To measure wind load on racking

Correct answer: To tighten electrical and mechanical connections to manufacturer-specified torque values

Using a calibrated torque wrench ensures connections are tightened to the exact specifications required for safe, reliable operation without over- or under-tightening.

Question 70: Which SRCC (Solar Rating and Certification Corporation) rating is used to compare solar water heating collectors?

ISO 9001 certification
ASHRAE 90.1 compliance
OG-300 System Rating
OG-100 Collector Rating (Correct answer)

Correct answer: OG-100 Collector Rating

SRCC OG-100 is the collector-level rating that measures thermal performance under standardized conditions, allowing consumers and installers to compare different collector models.

NABCEP PV Installation Professional (PVIP) Certification Exam

The NABCEP PV Installation Professional certification validates expertise in photovoltaic system design, electrical and mechanical installation, commissioning, and maintenance. It is the solar industry's most recognized credential for PV energy practitioners.

Questions

240 min

Time Limit

70%

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These practice questions were written with AI tools. They are not real exam questions. Exam facts are checked against the official sources listed below. Not reviewed by a subject-matter expert. Editorial policy

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nabcep.org — Eligibility, exam format, passing score, time limit, score validity, score release, test dates, fees, retake fee, test delivery · verified Oct 2026