NABCEP PV ASSOCIATE EXAM QUESTIONS WITH
VERIFIED SOLUTIONS.
An off-grid installation has a 1HP pump that is on 10% of the time and a 20W light that
is on 100% of the time. What is the monthly energy use? - ANS 68KWh
1HP = 746W
746W * 0.1 * 24hours * 30days = 53712Wh
20W * 24hrs * 30days = 14400Wh
14400 + 53712 = 68112Wh
68kWh
What kind of ground faults do most inverters detect? - ANS DC
Inverters detect dc ground faults. AC ground faults are detected on the AC side of the
inverter at the distribution paned (MSP, load center). Most inverters are not connected
to high or medium voltage. Medium voltage is thousands of volts, large utility scale
inverters are connected to medium voltage via a transformer
Current carrying ability of a conductor (wire) is called - ANS Opacity
According to ohms law and voltage drop, the relationship between voltage drop and
current is - ANS Proportional. Ohms law: V = I*R
More current makes more voltage drop. This is a reason why we need a larger wire with
more current, so the wire resistance is less with a larger wire and there will be less
voltage drop.
An array in a hot and dry place is not producing as expected in summer time. Which of
the following is NOT a likely problem:
a) Decreased ac wire size and voltage loss
b) String size too short
C) String size too long
D) Soiling - ANS C) String size too short. When it is hot, voltage can be low. Too long of
a string would be a problem when it is too cold not too hot.
When using a digital millimeter, what is the first thing you should do? - ANS Inspect the
meter. Always inspect first, look before you touch
Is the worst design error?
A) BIPV on a commercial job
B) A fast-growing tree to the north of an array in Idaho
C) PV at 5-degree tilt at 40 degrees latitude
D) Different tilt angles in a PV source circuit - ANS D) Different tilt or azimuth operation
within a source circuit is bad. Series connections should not have different orientations
MPPT is for - ANS MPPT is maximum power point tracking and will optimize the energy
harnessed from PV. Some inverters have multiple MPPTs. Charge controllers often, but
don't always, have MPPTs
Concentrated PV:
A) Only works with direct sunlight
B) Usually has a single axis tracker
C) Will get 30% power during cloudy conditions
D) Is using heat to make electricity - ANS A) Only works in direct sunlight. Usually works
with 2-axis trackers to always point at the sun and will not work at all in cloudy
conditions. Concentrated PV =! Concentrating Solar thermal
, Optimal tilt for off-grid PV system in the winter - ANS Latitude + 15 degrees is optimal tilt
to maximize winter production. The sun is lower in the winter, requiring a higher tilt
angle
What is the most acceptable rating of an enclosure for exposed circuit conductors
mounted on an outside wall? - ANS NEMA 3R
Bypass diodes are located in the
A) Combiner box
B) Inverter
C) Wiring harness
D) PV Module - ANS Bypass diodes are in PV module junction box. Diverts current
around a group of cells if one is shaded. Usually 3 diodes/PV module
PV array at higher elevation would tend to produce more - ANS Current. Higher
elevation, less atmosphere, more irradiance, more current. High elevation can also be
cooler meaning more voltage from cold temps.
How much 14% efficient PV fits on 25 Square Meters
A) 3000W
B) 4.5kW
C) 4000W
D) 3.5kW - ANS D) 3.5kW. 14% efficient = 0.14*1000W/M^2 = 140 W/m^2
140 * 25 = 3500W = 3.5kW
Which is the smallest conductor? - ANS 18 AWG
18 AWG, 10 AWG, 0 AWG, 3/0 AWG
What is the simplest type of PV system - ANS Direct coupled is the simplest with just
PV and a load that only works when the sun is out
Sun path charts differ based on - ANS Latitude
Series connections increase - ANS Voltage. Parallel increases current
The longest shadow at 2PM would be on - ANS the winter solstice (12/21)
What is the ground mount advantage over a rooftop system? - ANS Ground mount is
cooler hat rooftop because of better airflow, meaning higher voltage
Which test conditions have higher voltage?
STC
PTC
CEC
NOCT - ANS STC is higher voltage
Best tilt for annual production in most of the USA? - ANS 30 degrees
A 12V light is left on for 13 hours at 1.5A with a 12V battery. How much energy is used?
- ANS 0.234 kWh
12V * 1.5A * 13hr = 234 Who
A 12V light is left on for 13 hours at 1.5A with a 12V battery, how many Ah are used? -
ANS 19.5 Ah
1.5A * 13hrs
VERIFIED SOLUTIONS.
An off-grid installation has a 1HP pump that is on 10% of the time and a 20W light that
is on 100% of the time. What is the monthly energy use? - ANS 68KWh
1HP = 746W
746W * 0.1 * 24hours * 30days = 53712Wh
20W * 24hrs * 30days = 14400Wh
14400 + 53712 = 68112Wh
68kWh
What kind of ground faults do most inverters detect? - ANS DC
Inverters detect dc ground faults. AC ground faults are detected on the AC side of the
inverter at the distribution paned (MSP, load center). Most inverters are not connected
to high or medium voltage. Medium voltage is thousands of volts, large utility scale
inverters are connected to medium voltage via a transformer
Current carrying ability of a conductor (wire) is called - ANS Opacity
According to ohms law and voltage drop, the relationship between voltage drop and
current is - ANS Proportional. Ohms law: V = I*R
More current makes more voltage drop. This is a reason why we need a larger wire with
more current, so the wire resistance is less with a larger wire and there will be less
voltage drop.
An array in a hot and dry place is not producing as expected in summer time. Which of
the following is NOT a likely problem:
a) Decreased ac wire size and voltage loss
b) String size too short
C) String size too long
D) Soiling - ANS C) String size too short. When it is hot, voltage can be low. Too long of
a string would be a problem when it is too cold not too hot.
When using a digital millimeter, what is the first thing you should do? - ANS Inspect the
meter. Always inspect first, look before you touch
Is the worst design error?
A) BIPV on a commercial job
B) A fast-growing tree to the north of an array in Idaho
C) PV at 5-degree tilt at 40 degrees latitude
D) Different tilt angles in a PV source circuit - ANS D) Different tilt or azimuth operation
within a source circuit is bad. Series connections should not have different orientations
MPPT is for - ANS MPPT is maximum power point tracking and will optimize the energy
harnessed from PV. Some inverters have multiple MPPTs. Charge controllers often, but
don't always, have MPPTs
Concentrated PV:
A) Only works with direct sunlight
B) Usually has a single axis tracker
C) Will get 30% power during cloudy conditions
D) Is using heat to make electricity - ANS A) Only works in direct sunlight. Usually works
with 2-axis trackers to always point at the sun and will not work at all in cloudy
conditions. Concentrated PV =! Concentrating Solar thermal
, Optimal tilt for off-grid PV system in the winter - ANS Latitude + 15 degrees is optimal tilt
to maximize winter production. The sun is lower in the winter, requiring a higher tilt
angle
What is the most acceptable rating of an enclosure for exposed circuit conductors
mounted on an outside wall? - ANS NEMA 3R
Bypass diodes are located in the
A) Combiner box
B) Inverter
C) Wiring harness
D) PV Module - ANS Bypass diodes are in PV module junction box. Diverts current
around a group of cells if one is shaded. Usually 3 diodes/PV module
PV array at higher elevation would tend to produce more - ANS Current. Higher
elevation, less atmosphere, more irradiance, more current. High elevation can also be
cooler meaning more voltage from cold temps.
How much 14% efficient PV fits on 25 Square Meters
A) 3000W
B) 4.5kW
C) 4000W
D) 3.5kW - ANS D) 3.5kW. 14% efficient = 0.14*1000W/M^2 = 140 W/m^2
140 * 25 = 3500W = 3.5kW
Which is the smallest conductor? - ANS 18 AWG
18 AWG, 10 AWG, 0 AWG, 3/0 AWG
What is the simplest type of PV system - ANS Direct coupled is the simplest with just
PV and a load that only works when the sun is out
Sun path charts differ based on - ANS Latitude
Series connections increase - ANS Voltage. Parallel increases current
The longest shadow at 2PM would be on - ANS the winter solstice (12/21)
What is the ground mount advantage over a rooftop system? - ANS Ground mount is
cooler hat rooftop because of better airflow, meaning higher voltage
Which test conditions have higher voltage?
STC
PTC
CEC
NOCT - ANS STC is higher voltage
Best tilt for annual production in most of the USA? - ANS 30 degrees
A 12V light is left on for 13 hours at 1.5A with a 12V battery. How much energy is used?
- ANS 0.234 kWh
12V * 1.5A * 13hr = 234 Who
A 12V light is left on for 13 hours at 1.5A with a 12V battery, how many Ah are used? -
ANS 19.5 Ah
1.5A * 13hrs
