NABCEP PV ASSOCIATE EXAM |
Complete Questions and 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?
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?
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
Ampacity
According to ohms law and voltage drop, the relationship between voltage drop
and current is
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
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?
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
D) Different tilt or azimuth operation within a source circuit is bad. Series
connections should not have different orientations
MPPT is for
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
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
6 feet
Parallel PV circuit connections increase
Parallel increase current. Series increase voltage
Optimal tilt for off-grid PV system in the winter
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?
NEMA 3R
Bypass diodes are located in the
A) Combiner box
B) Inverter
C) Wiring harness
Complete Questions and 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?
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?
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
Ampacity
According to ohms law and voltage drop, the relationship between voltage drop
and current is
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
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?
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
D) Different tilt or azimuth operation within a source circuit is bad. Series
connections should not have different orientations
MPPT is for
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
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
6 feet
Parallel PV circuit connections increase
Parallel increase current. Series increase voltage
Optimal tilt for off-grid PV system in the winter
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?
NEMA 3R
Bypass diodes are located in the
A) Combiner box
B) Inverter
C) Wiring harness
