Associate Test Prep

book, installer manual, teams tests

True or False: Multimodal systems have to disconnect from the grid completely when the grid is down?

true

what is solar grid parity?

when energy produced by PV is less expensive than electricity produced by conventional means

what is the height at which you need fall protection? 4 ft

6 ft

8 ft

10 ft

6 ft

ladder ratio required?

1:4

1:3

1:5

1:4

Why is it better for electrical workers to use heavier fiberglass ladders rather than metal?

metal conducts electricity

Which is more dangerous as a source of power: PV or the utility?

utiltiy

What is another word for fuses and circuit breakers?

connectors

disconnects

over current protection devices

over current protection devices

since falling is the most common death cause in the construction industry, why are PFAS important?

personal fall arrest system: harness, shock absorbing lanyard, lifeline, anchor

what can digital multimeters measure?

voltage, current, resistance

what is another term for peak sun hour?

insolation

irradiance

radiation

insulation

insolation

What are STC for solar modules?

1000 w/m2, 25C (77F), 1.5 Atmospheric Mass

what is the latitude of the equator

0

where is the sun at solar noon?

due south

T/F- azimuth is the direction we measure on a compass

true

how much PV would you have if you use 15.6% efficient PV and you have 100 square meters?

156 watts/square meter * 100 square meters - 15,600 watts = 15.6 kW of PV

do bypass diodes sacrifice voltage or current?

sacrifice voltage for current

Vmp * Imp = ?

maximum power which is the power rating of the PV module

what does the maximum series fuse rating represent?

the rating of a fuse that will protect the PV. if the fuse is too big too much current will flow through. Most mods/connectors have a 15 or 20A max

What happens in the DC combiner (aka combiner box)?

where PV source circuits are combined to become a PV output circuit

what is a junction box?

an electrical box where connections are made

which two of the following devices are OCPD?

• fuses

• DC disconnects

• busbars

• circuit breakers

• service panel

fuses and circuit breakers

what two factors combine to create orientation?

tilt and azimuth

if a PV system has 15% loss, what would you use as the derate factor?

.85

where do PV source and output circuits meet?

the DC combiner aka combiner box

what does the temperature rating of the conductor affect?

ampacity

T/F- voltage drop is increased when the wire is either short or thick

FALSE- it is decreased

what is another name for AC or DC coupled systems?

multimodal or bimodal so that they can operate in utility interactive or stand-alone mode

array azimuth angle is …

the direction an array surface faces based on a compass heading

array tilt angle is…

the angle between the array surface and the horizontal plane

how many degrees is a 7:12 pitch roof?

25

30

40

55

30 degrees

What is a simple rule for minimum spacing between rows?

three times the height of the top of the row or obstruction in front of the array

distance between PV arrays and obstructions should be at least how many times the height of the obstruction?

two

Which article of the NEC is requirement for electrical installations?

NEC 110

NEC 300

NEC 690

NEC 110

what is NEC 480?

• charge controller requirements

• battery containers and installation

• electrical installation requirements

• battery containers and installation

is a string technically a series or parallel connection of PV modules?

series

if the maximum charge rates from the PV array multiplied by one hour is equal to 3% of the battery nominal amp-hour capacity or greater, what piece of equipment is required?

charge controller, NEC 690.72

when a system has more than one energy source, what is it called?

hybrid

What is a disadvantage of lower voltage systems?

higher currents need larger and more expensive conductors, ocpd, and switchgear

what is NEC 690.7?

• minumum voltage ratings

• maximum current output

• conductor sizing

• minumum voltage ratings

UL 1703

safety standard for flat-plate photovoltaic modules and panels

UL 1741

Inverters, connectors, controllers and interconnection system equipment for use with distributed energy resources

IEEE 1547

standard for interconnecting distributed resources with electric power systems

what does the W stand for on a conductor?

wet

T/F: battery systems are considered to be grounded when the PV power source is grounded?

True- NEC 690.71

If a PV system is turning off on hot sunny days, what could be a problem causing underperformance?

voltage gets too low, need more modules in series or smaller inverter

what is a common performance issue causing ground fault detection?

likely a fault on a source circuit (string) so measure separate circuits to find the fault.

common performance issue- a blown fuse in combiner

likely a positive to negative short circuit, multiple strings feeding backwards through one fuse in a combiner,

If an array is facing south at equinox at noon, what must the tilt angle be in order for the array to face directly at the sun at latitude 30? a. 33 degrees b. 48 degrees c. 18 degrees d. 30 degrees

D 30 degrees. If you were on the equator, you would be at zero latitude and the sun with be right over your head at solar noon at equinox. That would be zero latitude with a zero-degree tilt. If you were 1 degree latitude north, then you would have to tilt the module a 1 degree tilt to the south to compensate for being 1 degree from where you first were. If you are 30 degrees north and the sun is in line with the equator (equinox), then you would have to tilt your PV module 30 degrees to line up with the sun at solar noon at equinox

What does the temperature rating of the insulation of a conductor when designing a PV system effect

ability of the wire to carry current. In solar we often use wire that is rated for 90C

When a bypass diode kicks in from a leaf on a solar cell, which parameter would you see reduced on a single string with string level MPPT? a. Current b. Voltage c. Ohms d. Amp hours

b. Voltage

limit for voltage on 1 and 2 family dwellings is

600V

Which is the best and safest way to determine current in a PV output circuit? a. Megohmeter b. Insulation tester c. Clamp on ammeter d. Through a digital multimeter

c. Clamp on ammeter

A remote cabin uses the loads below per day, how much total energy is used per day? 1000W toaster for 6 minutes 1.2kW hot water heating element for 3 hours per day Three 17W LED lights for 3 hours per day iPhone 100 charger at 20W for 3 hours per day

c. 3.9 kWh

What is “blocking” used for? a. Bypass diodes b. Attaching to a roof in a place where there is no rafter c. Leveling off a parapet d. Inserting reverse current into a circuit to prevent forward bias current

b. Attaching to a roof in a place where there is no rafter. Blocking is done by roofers when they need to add a block to get the strength of a rafter when making an attachment

If you are going to work on the roof to fix a ground fault and the dc disconnect is on the ground level, which of the following is the best safety procedure? a. Grounding the ungrounded conductor before going on the roof b. Removing the GFCI fuse before going on the roof c. Leaving the disconnect in the on position d. Lockout Tagout

LOTO (lockout tagout) is a system of turning something off and then locking it in the off position, so that nobody comes by and tries to turn the system on while you are working on it

Who makes requirements for electrical safety for employees?

OSHA = Occupational Health and Safety Administration

Typical utility interactive systems in the US will: a. Sell to the utility with a feed in tariff (FIT) b. Export to the utility extra power for credit c. Use batteries d. Send energy to diversion loads

PV systems on buildings usually can export power to the grid for credit if they are producing more than they are using. This type of arrangement is called net-metering

When PV modules are tested by CSA to the UL 1703 standard, they are tested among other things for a. Power production over long periods of time b. Fire safety c. For maximum performance in cloudy conditions d. For temperatures down to -60C

fire safety

If and inverter indicates that there has been a ground fault, what is the first thing that a O&M technician should do?

Open all disconnects

T/F: Most inverters installed today do not have ground fault fuses

true

When handling PV modules on a roof in sunlight, what is the most common method of safety of the following? a. Take all connectors off the modules b. Test voltage every 5 minutes c. Make sure that connectors are open d. Keep tape over the glass and around the corners of the frames

Make sure that connectors are open

Part of the process of turning silicon into a solar cell is called? a. Anodization b. Oxidation c. Doping d. Dumping

These elements are often boron (P doping, P for positive) and phosphorous (N doping, N for negative)

How do residential rooftop mounting systems typically attach to a rooftop, so that they do not fly away when the wind blows?

a. Lag screws into rafters or purlins

What is the shape of a typical monocrystalline solar wafer? a. Circular b. Square c. Rectangular d. Square with rounded corners

d. Square with rounded corner (poly is square)

What is the largest array size of the following if you are using a 24V battery bank and a 20A charge controller? a. 500W b. 2kW c. 1000W d. 280W

We do not want to exceed voltage and current. Since we are saying the voltage is 24V and the current can’t exceed 20A, then doing math = 480, best answer is 280W

what color wires can be used for equipment grounding (aka earthing in international terms) for wires in the US?

green, bare, or green with yellow stripe

white or blue

yellow or blue

white or green

green, bare, or green with yellow stripe.

If it is a grounded conductor, it would be white in North America or blue in much of the rest of the world.

In the western part of the USA and Canada, what direction does the north arrow of a magnetic compass point? east or west of North?

East

You are rebuilding an old battery system for a PV museum and everything is in amps and amp hours. You are told that the system needs to have 33% more PV production on average than what the loads require. The loads will require 20Ah per day and the insolation will be 5PSH. If the module current at STC is 8A at Imp and 9A at Isc, how many PV source circuits would be needed to meet the minimum requirements stated here?

1

20Ah x 1.33 = 26.6Ah required

A = 26.6Ah / 5PSH = 5.32A

Since the Imp of the module is 8A, which is significantly greater than the 5.32A required, we can be comfortable that 1 single PV source circuit would be adequate for this design.

29. A multimodal inverter that has an internal automatic transfer switch would have to monitor what in order to transfer to backup power?

a. Current and voltage from PV array

b. Primary power source voltage

c. Primary power source current

d. Backup power source viability

Primary power source voltage- inverter monitors frequency and voltage of grid so it knows when to switch to stand-alone mode

where can you find Maximum series fuse rating of a module?

on the back of the mod. or Isc * 1.56 then rounding up to the next common fuse size. fuses are not always required when there are 1 or 2 strings.

is solar noon dependent on time zones?

no, can be different in places that are 5 miles apart

In many diagrams, what is the point where the PV output circuit becomes an inverter input circuit?

Combiner Box

Inverter terminal

DC disconnect

AC disconnect

DC disconnect

T/F multimodal systems can still give people power if the utility stops working

true

Which types of wires can be used for connecting modules beneath arrays with exposed conductors?

a. THWN-2 and THHN

b. XRS and FTP

c. PV wire and USE-2

d. NMC and RTTW

c. PV wire and USE-2

What causes the skin to be more conductive and dangerous when working with electricity?

moisture— think sweat, causes skin to be more conductive

A 16A interactive inverter output circuit will require a circuit breaker of how many amps?

20A-the current coming out of the inverter is multiplied by 1.25 to determine the size of the breaker (overcurrent protection device)

Of the following, which is worst for stand-alone lead-acid batteries?

a. Undersized PV array

b. Temperatures between 20C and 30C

c. Fine stranded conductors

d. Anti-islanding

a. Undersized PV array

What does a hydrometer measure?

a. Water temperature

b. Specific gravity of battery acid

c. Lithium density

d. Surfactant levels

b. Specific gravity of battery acid

T/F: the highest the sun can be is 180 degrees

FALSE: it is 90 which is straight overhead

what are the characteristics of the critical design month?

worst insolation and most load usage

what part of the module is most subject to damage during installation?

the backsheet due to contact with sharp edges and module corners

Every service panel has a capacity limit, which is determined by the busbar rating and is measured in…

amps