NABCEP PV Installation Professional Exam
Questions and Answers.
NABCEP - ANS North American Board of Certified Energy Practioners
JTA - ANS Job Task Analysis
The JTA outlines the expected duties of a qualified PV installation professional.
Conduit Fill
(i.e. Maximum Percent of Conduit Area Available for Conductors) - ANS NEC Chapter 9
Table 1
Voltage Drop Limits - ANS ASHRAE 90.1 Standards suggests no more than 3% of
nominal voltage.
NEC suggests no more than 5% in an "Informational Note".
Sun power standard is no more than 1%.
Voltage Drop Equation - ANS % drop = (0.2 x D x I x R)/V
Where:
D= one-way distance (in feet)
I = current (nominal actual value, no 125% factors, use Imp for solar circuits)
R = resistance of conductors (in ohms/1000ft)
V = voltage (typical, nominal, use Vamp for solar circuits)
Resistance values can be found in NEC Chapter 9 Table 8 "Conductor Properties"
What size FMC conduit should be used for four size 6 AWG XHHW conductors, one
size 8 AWG XHHW EGC and four 10 AWG THHN conductors? Only use the NEC code
book to answer this question. - ANS 1-1/4"
Use Chapter 9 Tables 4 and 5.
BIPV - ANS Building-Integrated Photovoltaics
Can single phase inverters be connected to 3-phase power systems? - ANS Yes, as
long as significant unbalanced voltages cannot result
705.100
What is the minimum bulbar rating for a subpanel used as an inverter ac combiner
panel to combine three 4000W, 240V single phase inverters? - ANS 125A
Rating of each breaker = 16.7 X 1.25 = 25A
, Sum of inverter breakers = 3 x 25A = 75A
Minimum size of back-fed breaker in main service panel = 3 x 16.7A x 1.25 = 62.2 -->
70A
Minimum size bus bars in subpanel x 1.2 = inverter breakers + utility breaker = 75A +
70A
Minimum size bus bars in subpanel = (75A + 70A)/1.2 = 121 --> 125A
705.12(D)(2)
Can an inverter output be connected to a subpanel instead of the main distribution
panel? - ANS Yes, see 705.12(D).
But be careful that each panel in series meets the minimum bulbar size requirements.
Grounded conductor - ANS A current carrying conductor that is intentionally bonded to
ground. It is the neutral conductor in any AC system.
Equipment grounding conductor (EGC) - ANS The green or bare copper conductor
linking exposed non-current-carrying metal parts of module frames, equipment and
enclosures
Grounding electrode conductor (GEC) - ANS The bare copper conductor connecting the
system grounding bus to a ground rod or to the earth.
Grounding electrode - ANS The rod or other buried electrode in the earth.
Grounding electrode system - ANS Several grounding electrodes effectively bonded
together.
Sizing EGC - ANS The EGC should never be smaller than 14 AWG. Size the EGC
according to Table 250.122
BOS - ANS Balance-of-System Components include all mechanical or electrical
components and hardware used to assemble and integrate major components in a PV
system together (i.e. all components in a PV system except modules and inverters)
Stand-alone PV systems - ANS PV systems that operate independently of other
electrical systems.
Interactive PV systems - ANS PV systems that operate in parallel with the electric utility
grid.
Solar azimuth - ANS The direction of the sun's horizontal projection relative to a point on
earth.
Questions and Answers.
NABCEP - ANS North American Board of Certified Energy Practioners
JTA - ANS Job Task Analysis
The JTA outlines the expected duties of a qualified PV installation professional.
Conduit Fill
(i.e. Maximum Percent of Conduit Area Available for Conductors) - ANS NEC Chapter 9
Table 1
Voltage Drop Limits - ANS ASHRAE 90.1 Standards suggests no more than 3% of
nominal voltage.
NEC suggests no more than 5% in an "Informational Note".
Sun power standard is no more than 1%.
Voltage Drop Equation - ANS % drop = (0.2 x D x I x R)/V
Where:
D= one-way distance (in feet)
I = current (nominal actual value, no 125% factors, use Imp for solar circuits)
R = resistance of conductors (in ohms/1000ft)
V = voltage (typical, nominal, use Vamp for solar circuits)
Resistance values can be found in NEC Chapter 9 Table 8 "Conductor Properties"
What size FMC conduit should be used for four size 6 AWG XHHW conductors, one
size 8 AWG XHHW EGC and four 10 AWG THHN conductors? Only use the NEC code
book to answer this question. - ANS 1-1/4"
Use Chapter 9 Tables 4 and 5.
BIPV - ANS Building-Integrated Photovoltaics
Can single phase inverters be connected to 3-phase power systems? - ANS Yes, as
long as significant unbalanced voltages cannot result
705.100
What is the minimum bulbar rating for a subpanel used as an inverter ac combiner
panel to combine three 4000W, 240V single phase inverters? - ANS 125A
Rating of each breaker = 16.7 X 1.25 = 25A
, Sum of inverter breakers = 3 x 25A = 75A
Minimum size of back-fed breaker in main service panel = 3 x 16.7A x 1.25 = 62.2 -->
70A
Minimum size bus bars in subpanel x 1.2 = inverter breakers + utility breaker = 75A +
70A
Minimum size bus bars in subpanel = (75A + 70A)/1.2 = 121 --> 125A
705.12(D)(2)
Can an inverter output be connected to a subpanel instead of the main distribution
panel? - ANS Yes, see 705.12(D).
But be careful that each panel in series meets the minimum bulbar size requirements.
Grounded conductor - ANS A current carrying conductor that is intentionally bonded to
ground. It is the neutral conductor in any AC system.
Equipment grounding conductor (EGC) - ANS The green or bare copper conductor
linking exposed non-current-carrying metal parts of module frames, equipment and
enclosures
Grounding electrode conductor (GEC) - ANS The bare copper conductor connecting the
system grounding bus to a ground rod or to the earth.
Grounding electrode - ANS The rod or other buried electrode in the earth.
Grounding electrode system - ANS Several grounding electrodes effectively bonded
together.
Sizing EGC - ANS The EGC should never be smaller than 14 AWG. Size the EGC
according to Table 250.122
BOS - ANS Balance-of-System Components include all mechanical or electrical
components and hardware used to assemble and integrate major components in a PV
system together (i.e. all components in a PV system except modules and inverters)
Stand-alone PV systems - ANS PV systems that operate independently of other
electrical systems.
Interactive PV systems - ANS PV systems that operate in parallel with the electric utility
grid.
Solar azimuth - ANS The direction of the sun's horizontal projection relative to a point on
earth.
