NABCEP PV ASSOCIATE EXAM Questions with
Correct Answers
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?
Correct Answer-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? Correct Answer-
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 Correct Answer-
Ampacity
According to ohms law and voltage drop, the relationship between
voltage drop and current is Correct Answer-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 Correct Answer-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 multimeter, what is the first thing you should do?
Correct Answer-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 Correct Answer-D)
Different tilt or azimuth operation within a source circuit is bad. Series
connections should not have different orientations
, MPPT is for Correct Answer-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 Correct Answer-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
Fall protection should be used at heights over Correct Answer-6 feet
Parallel PV circuit connections increase Correct Answer-Parallel
increase current. Series increase voltage
Optimal tilt for off-grid PV system in the winter Correct Answer-
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? Correct Answer-NEMA 3R
Correct Answers
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?
Correct Answer-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? Correct Answer-
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 Correct Answer-
Ampacity
According to ohms law and voltage drop, the relationship between
voltage drop and current is Correct Answer-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 Correct Answer-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 multimeter, what is the first thing you should do?
Correct Answer-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 Correct Answer-D)
Different tilt or azimuth operation within a source circuit is bad. Series
connections should not have different orientations
, MPPT is for Correct Answer-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 Correct Answer-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
Fall protection should be used at heights over Correct Answer-6 feet
Parallel PV circuit connections increase Correct Answer-Parallel
increase current. Series increase voltage
Optimal tilt for off-grid PV system in the winter Correct Answer-
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? Correct Answer-NEMA 3R
