Vocabulary Flashcards by Clifton Thompson

Alternating Current

electrical current that changes direction of flow. In the North American
power system power changes direction 60 times each second. In other countries the electricity
changes 50 times each second.

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AC Coupied System

A blend of off-grid bi-modal and hybrid renewable energy systems. This
system will disconnect from the utility grid in the event of a failure of the grid and will continue to
provide power to selected critical circuits. What sets this system apart from other systems is that
it is comprised of several inverters. One known as the master inverter and one or more micro
inverters. In the event of a grid failure the master inverter disconnects the system from the utility
grid and continues to work in an off-grid mode. This allows the system to act as a utility grid and
the other inverters to continue to produce power. That power contributes to the overall system. If
there is a surplus power produced, larger than what is consumed by the load, the master inverter
can act as a battery charger that will charge the batteries while still acting as the utility grid to the
other inverters in the system. If the batteries should become fully charged while the load is still
minimal the master inverter will deter the other inverters from producing power. At this point the
batteries will produce power. The inverters will resume producing power after 5 minutes if the
surplus continues this process will repeat. This name is given due to the energy transfer from the
inverters are accomplished through AC power rather than DC.

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Air Mass, AM

The measure of how far light travels through the earth’s atmosphere. AM1 (one air
mass) is the thickness of the earth’s atmosphere. AM0 describes solar irradiance in space where it
is unaffected by the atmosphere. The power density of AM1.5 light is roughly 1,000 W/m 2 and the
power density of AM0 is 1,360 W/m 2 . This is known as the Solar Constant. This term can be used
to characterize the solar spectrum after solar radiation has traveled through the atmosphere. AM1
is the path from a sea level location to the sun being directly overhead. This is not always equal to
12pm in most cases due to the variety of location and seasons when the sun is directly overhead.

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Albedo

Solar radiation that is reflected from the ground, ground cover or bodies of water on the
earth’s surface.

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American Wire Gauge, AWG

The standardized system of measurement for electrical wire sizing.
This sizing system labels smaller wires with larger numbers and thicker wires with a smaller
number.

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Amorphous Photovoltaic

These modules appear brownish in color and are commonly
constructed from a silicon that is applied like other thin film materials. Often found used in similar
applications to calculators.

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Amp

An electrical current. A measurement of the quantity of electricity flowing in a circuit. Like
how gallons of water flow through a pipe per minute.

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Amp-Hour, AH

a measure of the amount of electrical current flowing for a given period of time.
10. Array – Two or more Photovoltaic modules connected.

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Azimuth Angle

the angle between the horizontal direction of the sun and a reference direction
typically north. This angle for photovoltaic modules are 180 degrees.

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Balance of System, BOS

All parts of a solar electric system other than the photovoltaic modules.
These components include inverters, racking, wires, conduit, switches, fuses and so forth.
13. Beam Radiation – The amount of solar radiation from the direction of the sun.

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What is the NABCEP

A PV array receives an average of 900 W/m 2 for 5 hours a day. What is the total amount of solar
energy the PV array receives during a 7-day period?
a. 45.00 kWh/m 2
b. 3.15 kWh/m 2
c. 4.50 kWh/m 2
d. 31.50 kWh/m 2

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What is the initial necessary step to ensure code compliance for a PV system installation?

a. Perform a shading analysis
b. Analyze the client’s electric usage
c. Determine local requirements
d. Apply for building permits.

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At what time of year during solar noon will an object cast the longest shadow in the Northern
Hemisphere?

a. June 21 st , Summer Solstice
b. March 21 st , Spring Equinox
c. December 21 st , Winter Solstice
d. September 21 st , Fall Equinox.

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Rooftop mounting systems transfer the weight of the PV system and its associated wind, snow
and seismic loads to the roof’s tissues or rafters through which component?

a. The structural attachments
b. The end and mid clamps
c. The rails
d. The L feet

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A video surveillance camera is powered by a PV module that produces 10 amps. The camera
operates at 12 volts. How much power is the module sending out to the camera?

a. 26 watts
b. 260 watts
c. 120 watts
d. 144 watts

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The grounding electrode conductor of a PV system should be what color?

a. Black
b. Green
c. White
d. Red

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What is the primary power source for a grid tied inverter?

a. The PV array
b. The battery bank
c. The main service panel
d. The utility

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What parameter on a PV module’s IV curve is used to calculate the minimum number of
modules to be configured in a series string?

a. Imp
b. Vmp
c. Isc
d. Voc

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What is the reason for grounding PV systems?

a. To establish a connection to the earth
b. Provides a path for fault currents and lighting induced surges to dissipate safely
c. It improves power output from the array
d. It establishes resistance levels for the PV system.

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According to OSHA, what is the minimum height in which a worker can fall where fall protection
measures shall be in place?

a. 4 ft
b. 6 ft
c. 8 ft
d. 10 ft

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Which of these types of PV systems has the fewest number of components and is most
efficient?

a. Interactive System
b. Bi-Modal System
c. Direct Coupled System
d. Hybrid System

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What function does a maximum Power Point Tracker perform?

a. Monitors and reports power levels of the PV array
b. Keeps the modules pointed and the optimum solar incidence angle
c. Optimizes power output of the array due to variable irradiance and temperature levels
d. Passes power around rather than through a shaded string

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Standard Test Conditions (STC) for irradiance is what?

a. 25 degrees Celsius
b. 800 W/M 2
c. 30 degrees Celsius
d. 1,000 W/M 2

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The monitoring system on the inverter of a roof top interactive PV system is reporting low levels
of irradiance and low system current. What is the most likely cause?

a. High array temperature
b. A ground fault condition exists
c. Low array temperature
d. It is cloudy and the system is operating normally.

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An off-grid road sign requires 150Ah per day to operate. To design a system that offers 5 days of autonomy with a battery system that has a maximum depth of discharge of 50%. What would be the minimum requirement of this battery bank capacity?

a. 1250 Ah b. 1500 Ah c. 1000 Ah d. 375 Ah

Using the sun path chart of 40 °north what is the approximate altitude angle of the sun at solar noon in the month of February?

a. 60 ° b. 50 ° c. 30 ° d. 40 °

Using the sun path chart what is the approximate azimuth angle of the sun at 1 pm in the month of April?

a. 210° b. 195° c. 225 ° d. 240 °

What is the primary purpose of a charge controller (PV controller)?

a. To condition power for the purpose of battery charging b. To convert DC power to AC power for the purpose of battery charging c. To ensure that temperature levels are kept in a safe operating range d. To protect the batteries from over charge and over discharge

A 270-watt PV module has an open circuit voltage of 39.2 V at STC and a Temperature Coefficient of Voc of .31%/C°. what would be the temperature corrected voltage at an operating temperature of -5°C?

a. 42.9 V b. 41.6 V c. 35.5 V d. 36.8 V

A PV system produces 5,000 watts at 240 volts AC. What is the minimum amperage rating for the PV breaker and conductors feeding that breaker?

a. 20 amp b. 25 amp c. 30 amp d. 50 amp

A stand-alone inverter is sized based on the side of what?

a. Battery bank geb. PV array 2. Ch

A stand-alone inverter is sized based on the side of what?

a. Battery bank b. PV array c. Change control output d. DC Disconnect

The standard for which PV modules in the United States are tested and certifies is what?

a. IEC 6772 b. NEC 690 c. UL 1703 d. NFPA 70

``` If a certain PV module produces 9A at 36V and three strings of 10modules combined in parallel at the combiner box, what amperage ratings would the OCPD’s need to be for each string? ```

a. 30A b. 45A c. 50A d. 15A

What resistance must be applied to a 48V 8A module to operate at maximum power?

a. 3.75Ω b. 6Ω c. 0.167Ω d. 384Ω

What is the amount of irradiance required to the test PV cells and modules at NOCT?

a. 800W/m b. 1,000 W/m 2 c. 900 W/m 2 d. 700 W/m 2

You just installed a PV array using a micro inverter system. Where should the DC disconnect be located?

a. Between the AC Disconnect and the Main Service Panel b. Between the module and the combiner box c. Between the sub-panel and the meter d. No DC disconnect is used in a micro inverter system

Bypass diodes are commonly located in which system component

a. Modules b. Inverters c. Charge controllers d. DC disconnects

The intentional controlled over-charge batteries which causes gassing that helps to ensure that each cell is brought to full charge is called what?

a. Float charging b. Absorption Charging c. Bulk Charging d. Equalization Charging

12 ohms of resistance is applied to a 10-amp rheostat which is plugged into a household outlet. How much power is being applied to the circuit?

a. 120 W b. 1,200 W c. 480 W d. 240 W

When designing a PV system using 250 W modules with a Voc of 36 V. The inverters operating voltage range is 250V – 560V. what is the maximum number of modules that can be connected in series considering a low voltage correction factor of 1.20 according to the NEC.

a. 12 b. 13 c. 8 d. 15

When using a sizing grid system for a customer who consumes 12,775 kWh per year. After visiting the site then determine the location, tilt and azimuth will yield an average of 5 PSH (peak sun hours), and the total system efficiency is 85%, using modules with an STC rating of 250W. what is the size of the system in DC watts in order to supply 100% is this the clients annual usage IN KW?

Which of the following components, listed below, are required for a stand alone PV system?

a. Bi-modal Inverter b. Stand-By Gen Set c. Battery Bank d. Two axis txis tracking system

An off grid home uses 550W for 4.5 hours, 75W for 2 hours, 50 W for 7 hours, 150 W for 1.5 hours and 5.3 kW for 15 minutes. What should the total energy usage be?

a. 4847.5 Wh b. 3.163 kWh c. 3957 Wh d. 4.4875 kWh

Assuming a module efficiency of 17% and irradiance of 900 w/m 2

a. 4950 W b. 4.59 kW c. 45.9 kW d. 2.7 kW

The hydraulic equivalent of current is what?

a. Pressure b. Flow c. Resistance d. Friction

Which of the following has the Authority Having Jurisdiction, AHJ, has the primary responsibility?

a. Ensuring the PV system meet inter-connection requirements b. Evaluate the system is generating the power it is supposed to c. Determine that the PV system complies with industry best practices d. Make the determination that the system meets code compliance standards

What is the primary purpose of a bypass diode?

a. To prevent against islanding b. To decrease the negative effects of shading c. To minimize overheating of PV cells D.. To protect against overcurrent.

A ground fault has been indicated in a grid tied inverter. What should the technician do first?

a. Check the fuse and replace if needed b. Check connections in the combiner box c. Turn off the DC and AC disconnects d. Test string voltage at the junction box

Which of the following most accurately describes the purpose of a transformer?

a. Converts AC current to DC current b. Adjust resistance to maintain maximum power C. Step up/down AC voltage d. Increase/decrease AC current

INSERT CHART Using the IV curve above which power producing point represents the highest amount of voltage?

a. a b. E c. c d. D

Identify the point on the above IV curve that represents Pmp.

a. a b. b c. C d. d

identify the point on the above IV curve that represents the highest amount of current where voltage across the circuit is zero.

a. A b. b c. c d. d

``` A certain PV module has an open circuit voltage, Voc, of 36.5 V at STC and a voltage temperature coefficient of 0.45%/C°. what will be the temperature corrected voltage for this module at an operating temperature of 45C°? ```

a. 39.8 V B. 33.2 V c. 52.9 V d.d

Which three parameters are typically listed on an interactive inverter spec sheet?

a. Isc, Voc, Pmp B. Input voltage, output voltage, continuous power rating c. Pmp, output voltage, input voltage d. Vmp, Imp, STC

What component of an off-grid PV system is typically located between the PV array and the battery bank?

a. DC disconnect b. Inverter c. Charge Controller d. Auxiliary power transfer switch

A ground mounted PV system facing due south in La Crosse, WI. (44° N latitude) would maximize its summer energy harvest by adjusting what?

a. Tilt to 44° b. Tilt to 59° C. Tilt to 29° d. Azimuth to 90°

What room should never be installed as a DC disconnect?

a. Bathroom b. Garage c. Kitchen d. Bedroom

Which component in an off-grid system is directly related to the autonomy of the system?

a. PV ARRAY b. Charge controller c. backup generator D. battery bank

Interactive inverters used for off grid tied applications usually contain what?

a. Bypass diodes b. Charge Controller c. Ground-fault protection device d. Array temperature sensors

If a PV array produces a 4.5 kW DC, how much energy would be produced over the span of 30 days. Assuming 5.5 PSH and 16% losses through the system?

a. 742.5 kWh b. 623.7 kWh c. 861.3 kWh d. 20.7 kWh

During a ground fault condition where the metallic equipment becomes energized what protects against electric shock?

a. The underground conductor b. The grounding electrode conductor c. The equipment grounding conductor d. The AC grounded conductor

What type of PV array mounting system is commonly used on commercial flat roofs to avoid penetrating the roofs surface?

A. A ballasted mount system b. A rack mount system c. A stand-off mount system d. A rail-less mounting system

``` Given the module specifications below what is the minimum number of modules that can be wired in series and operate within an inverters operating voltage range of 250V -480V? assuming Standard Test Conditions. ```

a. 9 b. 8 c. 10 d. 7

What is the most significant outcome of a Solar PV system operating in an environment that is much warmer than STC?

a. Current would decrease b. Voltage would increase c. Current would increase

The surface of a roof has 50m 2 of useable space to accommodate a PV array, using modules that have a rated efficiency of 15% at STC what is the largest array size in kW DC?

a. 4.5 kW b. 3.5 kW c. 15 kW d. 7.5 kW

What crystalline silicon manufacturing process uses a single crystalline seed dipped repeatedly in a vat of molten silicon that is slowly rotated?

a. Polycrystalline Silicon b. Monocrystalline Silicon c. Amorphous Silicon d. Thin Film Silicon

The hydraulic equivalent of voltage is what?

a. Flow b. Friction c. Pressure d. Intensity

A main service panel has a buss bar rating of 200 A and a main breaker of 175A. what is the maximum amperage rating of OCPD protecting the PV circuit that can be back fed into this panel according to the NEC?

a. 40 amps b. 50 amps c. 0 amps, the panel must be upgraded D. 65amps

Power to energy as Irradiance is to what?

a. Insolation b. Radiation c. Conductance D. Irradiance

What is the correct sequence of energy flow of the utility grid system?

a. Generation-Distribution-Transmission-Service b. Generation-transmission-distribution-service c. Production-distribution-transmission-service d. Transmission-service-generation-distribution

Three PV source circuits of 350V at 8A each are combined in parallel at the combiner box. What is the total amperage that must be used to size the PV output circuit conductors?

a. 24A b. 37.5A c. 30A d. 8A

The ampacity of a conductor is affected most by which of the following?

a. Temperature B. Irradiance c. Voltage d. Resistance

Imp for a PV source circuit is 5A. what is the voltage drop over the 200 feet from junction box to inverter if system voltage is 300V and AWG #12 wire is used with Ω/kft of 1.93? and what is the percentage of voltage drop?

a. 4.5V and 3% b. 4.5V and 2.8% c. 3.9V and 1.3%