Flash card material
Area of a circle
3.14 x radius ^2
Area of a cylinder
depth x 3.14 x radius ^2
Volume
Length x width x height
How many cm per inch
2.54cm
How many feet per meter
3.28
Wind category B
urban/suburban or wooded with close obstructions
Wind category C
Scattered obstructions
Wind category D
No obstructions and wide open
Wind category A
No longer in use
Roof zone 3
roof corners
Roof zone 2
roof edges
Roof zone 1
middle of roof (best for solar)
Another name for PV Source Circuit
string
Another name for Dc-to-dc converter
Optimizer
Fancy name for solar panel
PV Module
Where is a PV Source circuit located?
Between PV and Combiner box
Where is a PV Output circuit located?
After parallel connections in a combiner
PV maximum current
Isc x 1.25
PV required ampacity for continuous current
Isc x 1.56
Required ampacity for continuous current for other than PV source and output circuits
125% of current
When is 156% Ampacity correction used
Only for PV source and output circuits
When is 156% Ampacity correction not used
Conditions of use calculations
Do not
calculate continuous current and conditions of use in the same calculation
OCPD size formula
maximum current x 1.25 AND round UP
What is required if disconnects are in different locations?
directory or plaque at each disconnect
When is string sizing rounded down?
Cold temperature high Voc calculations
When is string sizing rounded up?
Hot temperature low Vmp calculations
Rapid shutdown array boundary
1 foot outside / 3 feet inside
Pilot holes must be
67-80% of a lag bolt size
Fine stranded cable must be paired with
Fine-stranded rated lugs
When are different string orientations acceptable?
Only with dc to dc converters
Width of working space
width of equipment or 30” whichever is greater
When is “time of use” most expensive
Summer afternoons
When are “tiered” utility rates most expensive
The more you use
Sine waves are
less harmonic distortion
Conductors inside outdoor conduit must be
wet-rated
80% STC irradiance (W/m^2)
800 W/m^2
ASHRAE
Dataset for temperatures and wind speeds
Multimodal inverters
Can power critical loads when the grid shuts down
Ground fault protection is required on
PV on buildings
Insulation testing is done with a
Megohmmeter (megger)
What color(s) are grounded conductors in N. America?
White or gray
Ground rods are
Copper coated steel, 5/8” in diameter and 8’ long
Do not use a aluminum GEC when
incased in concrete
Functional grounded inverters
include fuse grounded and transformerless inverters
Functional grounded inverters wire type
PV wire, or USE-2 on source circuits
Functional grounded inverter fusing
only requires fuses on one polarity if fused in combiner
Bypass diode failure usually decreases voltage by how much
1/3rd of a module
120/240 is called what
Split phase or single phase
120V inverters
have a single pole ac disconnect/breaker and are mostly seen in off grid systems
No multi-wire branch circuit signs required
with 120V inverter
No more than ____ switches to turn off PV systems on a building
Six
No disconnect on _______________ with exceptions for GFDI, AFCI and maintenance.
Grounded conductors
Which circuits must be separated from other circuits?
PV Source & Output circuits.
When is a load break rated manual disconnect located within 10 feet of a combiner?
If the current is greater than 30A
Can be a connector or a disconnect, must be within 10 feet of equipment
Isolating device
Interactive inverters don’t need a clamped breaker
Bond rails to each other
UL 1741
UL Listing for Inverters
UL 1703
UL Listing for PV Modules
Maximum height for a DC Disconnect
6.5 feet
Add acid to water so acid doesn’t splash
Solidly grounded conductors don’t need
disconnect’s or fuses
Dead load
Anything permanent (solar system, HVAC)
Designated safety person may not
be distracted
No DC Disconnect where
Bathroom (wet feet)
Do not bond a neutral into two places
If disconnects aren’t near each other what is required?
plaque or directory
What battery chemistry requires cell equalization?
Lead acid
Battery working spaces require what
lights
What is the safest ladder?
Fiberglass with aluminum steps
USE-2
Underground Service Entrance cable
Suitable for direct burial, UV resistant,
THWN-2
Thermoplastic High heat Water resistant Nylon coated.
“2” at the end refers to a 90 degrees C temperature rating.
Temperature corrected MAXIMUM VoC Formula
VoC x (100% + ((delta T) x TkVoc))
Temperature corrected MINIMUM Formula
Vmp x (100% + ((Tadd+Tmax-Tstc) x TkPmp))
What is the “Tadd” variable in voltage calculations?
accounts for the increased temperatures of PV cells above ambient temps under operating conditions,
Roof mount= 30 degrees
Ground mount= 25 degrees
Pole mount= 20 degrees
^^^adders above ambient temperature
RHW-2
