NABCEP - PV Installation - Exam 1 Questions with
Correct Answers
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 often at a distribution panel, i.e., main service
panel, load center or switchgear.
Which is the worst design error? Correct Answer-Different tilt angles in
a PV source circuit
- Different tilt or azimuth orientation within a source circuit is bad.
Series connections should not have different orientations.
A system that sits on a flat/low-slope rooftop and has no penetrations is
called a Correct Answer-Ballasted system
- Ballasted systems are common fat low slope (fat) roof systems that are
not penetrating the roof. A ballast is something that is relatively heavy
keeps the PV from blowing away.
What will be increased by reflective surfaces (albedo)? Correct Answer-
Current
,- Reflections and increased light increases current. Reflected light can
also be called albedo
Which room cannot have a PV dc disconnect? Correct Answer-
Bathroom
- PV dc disconnect not allowed in bathroom (think of wet feet).
Best sealant for residential rooftop? Correct Answer-Polyurethane
- and silicone are the best rooftop sealants (Polyurethane is even better
than silicone). Silicone is a sealant; silicon is what solar cells are made
of. There is a big difference.
In California (west of the zero-degree isogonic line) the north needle of
the compass will point? Correct Answer-East of true North
- In California, magnetic declination is to the east. This means that the
north end of the compass will point slightly to the east.
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? Correct
Answer-30 degrees
- Explanation: 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. If you were at 90 degrees
latitude on the north pole, you would have the sun on the horizon and
would have to tilt your PV at a 90- degree tilt to directly point at the sun.
What is "blocking" used for? Correct Answer-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. There are cases where a
solar installer wants to make an attachment in a place on a roof where
there is no rafter, so they can take a block of wood and fasten it to
adjacent rafters to get a strong connection. Wooden roofs are often made
with rafters and on top of the rafters is a roof deck, which is often made
of plywood or oriented strand board (OSB). The roof deck itself is
considered by most to not be strong enough to fasten a solar system to,
so the connection will be made to the rafters. Rafter roofs have the
rafters on a sloped roof go from up to down. Other types of roofs use
purlins instead of rafters and purlins will go from side to side on the
roof. Most metal roofs are purlin roofs. There is a diode called a
blocking diode, which prevents reverse current.
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? Correct Answer-Lockout Tagout
Correct Answers
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 often at a distribution panel, i.e., main service
panel, load center or switchgear.
Which is the worst design error? Correct Answer-Different tilt angles in
a PV source circuit
- Different tilt or azimuth orientation within a source circuit is bad.
Series connections should not have different orientations.
A system that sits on a flat/low-slope rooftop and has no penetrations is
called a Correct Answer-Ballasted system
- Ballasted systems are common fat low slope (fat) roof systems that are
not penetrating the roof. A ballast is something that is relatively heavy
keeps the PV from blowing away.
What will be increased by reflective surfaces (albedo)? Correct Answer-
Current
,- Reflections and increased light increases current. Reflected light can
also be called albedo
Which room cannot have a PV dc disconnect? Correct Answer-
Bathroom
- PV dc disconnect not allowed in bathroom (think of wet feet).
Best sealant for residential rooftop? Correct Answer-Polyurethane
- and silicone are the best rooftop sealants (Polyurethane is even better
than silicone). Silicone is a sealant; silicon is what solar cells are made
of. There is a big difference.
In California (west of the zero-degree isogonic line) the north needle of
the compass will point? Correct Answer-East of true North
- In California, magnetic declination is to the east. This means that the
north end of the compass will point slightly to the east.
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? Correct
Answer-30 degrees
- Explanation: 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. If you were at 90 degrees
latitude on the north pole, you would have the sun on the horizon and
would have to tilt your PV at a 90- degree tilt to directly point at the sun.
What is "blocking" used for? Correct Answer-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. There are cases where a
solar installer wants to make an attachment in a place on a roof where
there is no rafter, so they can take a block of wood and fasten it to
adjacent rafters to get a strong connection. Wooden roofs are often made
with rafters and on top of the rafters is a roof deck, which is often made
of plywood or oriented strand board (OSB). The roof deck itself is
considered by most to not be strong enough to fasten a solar system to,
so the connection will be made to the rafters. Rafter roofs have the
rafters on a sloped roof go from up to down. Other types of roofs use
purlins instead of rafters and purlins will go from side to side on the
roof. Most metal roofs are purlin roofs. There is a diode called a
blocking diode, which prevents reverse current.
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? Correct Answer-Lockout Tagout
