Reading Questions Flashcards
1
Q
If PV is used to charge batteries without an MPPT charge controller what will the PV voltage have to match?
A
batteries
2
Q
Why type of tracker follows the sun through the day?
A
2 Axis
3
Q
What do parallel connections increase?
A
Current
4
Q
In string sizing, when calculating for shortest and longest string size, which of them is a safety concern and which is a production issue?
A
Maximum = Safety : Minimum = Production
5
Q
6’ long screw that is screwed into the earth
A
Ground screw
6
Q
What is blocking used for?
A
Attaching to a roof in place where there is no rafter
7
Q
Most of the PV installed in the world is less than how many years old?
A
3
8
Q
What are the design requirements for a self-regulating system?
A
Has to be designed so it won’t charge over 3% of the battery capacity in an hour.
9
Q
What is Imp?
A
Maximum Power Current
10
Q
What is the proper ladder ratio?
A
1:4
11
Q
What are two types of OCPD’s?
A
Fuses and Circuit Breakers
12
Q
What are the components of a direct-coupled PV system?
A
PV and Load
13
Q
Where is the only place in the world that the sun will be directly overhead?
A
The tropics
14
Q
What type of PV uses magnifying lenses or focused light onto an efficient solar cell?
A
Concentrating PV
15
Q
What is the most common and best type of roof sealant?
A
Polyurethane
16
Q
What is the battery stage where there is a trickle charge to keep the battery charged?
A
Float
17
Q
What is a hybrid PV system
A
Includes another source of power besides PV, batteries, or the utility.
18
Q
What is most likely the cause of a blown fuse in a combiner box?
A
A positive to negative short circuit
19
Q
How is most of the PV in the world mounted today?
A
Ground Mount
20
Q
What has more current; Imp or Isc?
A
Isc
21
Q
What is the best angle for annual production?
A
Latitude tilt or 30-degree tilt (depending on location)
22
Q
What is the formula for maximum power?
A
Imp x Vmp
23
Q
What do you call a device that measures global radiation?
A
Pyranometer
24
Q
What are the main components of a DC coupled battery system?
A
Solar Modules : Charge Controller : Battery : Inverter
25
What are the conductors between the battery and the battery inverter called?
Battery Inverter Input Circuit
26
Where would you have more voltage, where it's coming from or where it's going?
Where it's coming from
27
What has more voltage; Voc or Vmp?
Voc
28
Connectors connected to the backs of PV modules are ______
Polarized
29
In referring to derating, should you think about what you are losing or keeping?
Keeping
30
What are the symbols for: Current : Voltage : Power
I : V : P
31
Grounding (bonding) of functionally ground d PV system on a roof should be done to what?
Racking and aluminum frames
32
What do you call a system with batteries that operates when connected to the grid
Self-Consumption
33
Where is a charge controller located?
Between the PV and the batteries
34
If the wire on the ac side of the inverter was long and thin, the voltage at the the inverter relative to the grid; would go up or down?
Would go up
35
What are the stages of battery charging?
Bulk : Absorption : Float : Equalization
36
What is it called when batteries take extra energy from the day and supplement the usage at night?
Self-Consumption
37
How does colder temperatures effect performance?
Increases voltage
38
What was the name of the first solar powered satellite?
Vanguard 1 by the US Navy in 1958
39
What does a hydrometer do?
It checks the battery acid with a density test
40
What is the most popular type of PV system?
Grid-Tied aka Utility Interactive
41
What are the most efficient solar cells made from?
Gallium Arsenide
42
Below 23.5 degrees north latitude is called what?
Tropic of Cancer
43
What is the Critical Design Month?
The month with the worst solar irradiation
44
The cleaner your PV system the more you will increase _______?
Current
45
What is Distributed Generation?
When electricity is made where people live.
46
This type of battery is often called maintenance free because you cannot add fluids.
Sealed Valve Regulated Flooded Lead Acid Battery
47
(T/F) Charge controllers are used in self-regulating systems?
False
48
A typical off-grid system where charge controllers are used to charge batteries is what type of system?
DC Coupled System
49
What is the formula for resistance?
V = I x R
50
What is a demand charge on a utility bill for? Power or Energy
Power
51
This device helps regulate the charging of batteries to prevent them from under or over charging.
Charge Controller
52
Name (3) types of fall protection
Guard Rails : Safety Nets : Personal Fall Arrest System (PFAS)
53
What instrument can best test the insulation resistance of a conductor?
Megohmmeter
54
A common term used for a solar resource measured in kWh/Square meter/day is:
Insolation
55
What are the main conditions for STC?
1000 Watts per square meter : 25℃ (77℉) : 1.5 Atmospheric Mass
56
How long does a system take to turn on and start reporting to the grid?
5 minutes
57
Most of the world operates on what frequency?
50 hertz
58
What is a live load? Give an example
A temporary load on a roof (workers, snow)
59
What battery stage is the charge slowing down?
Absorption
60
Is the top layer of a solar cell usually positive or negative?
Negative
61
What is the formula for Distance?
Distance = Speed x Time
62
What is a good number for American's to ballpark for square footage on an array?
100-150W
63
For a supply side connection, what would limit the output of the inverter more: Service entrance conductor ampacity or load side breaker ampacity
Service entrance conductor ampacity
64
What does nominal mean?
In name only
65
What reduces voltage drop? Long and thin or Short and Thick wires?
Short and Thick
66
What would be the problem if a system is turning off on hot sunny days? What would be the fix?
Voltage gets too low when the temp gets high so you would need to put more modules in series or get an inverter that operates at a lower voltage
67
Name two devices used to measure shade
Solmetric Suneye & Solar Pathfinder
68
What is the UL listing for inverters in North America?
1741
69
Color of equipment grounding conductor?
Green
70
How many points of system grounding should there be?
A single point of system grounding
71
Will utility-interactive PV systems will not work during a power outage?
No
72
What is power?
The rate at which electricity is used
73
What is a PV output circuit?
At the output of a DC combiner is the PV output circuit which is the combined current of the PV source circuits.
74
If the irradiance is increased, what else will increase?
Current
75
Does STC test temperatures of the cell or ambient?
Cell
76
What is the hydraulic analogy for flow?
Current
77
What kind of battery is similar to a fuel cell where electrolytes are pumped between reactor and storage tanks?
Flow Battery
78
Who created the first "Solar Battery"?
Bell Labs
79
What is a non-isolated inverter?
An inverter without a transformer
80
Do devices that have MPPT need to be connected to PV?
Yes
81
What is solar-grid parity?
When energy produced by PV is less expensive than electricity produced by conventional means.
82
What are the characteristics of a polycrystalline silicon solar cell?
Square Corners
83
How are wind loads measured in the US?
(Psf) pounds per square foot
84
What is the best charging range for a 12V lead-acid battery?
14-15V
85
What is albedo radiation?
Radiation that is reflected off something else (trees, lakes, white roof, etc)
86
An inverter that gets voltage from a battery and produces current and power as it's needed.
Battery Inverter
87
What was the total amount of solar installed by 1999?
1 GW
88
What did Einstein win a Nobel Prize for?
Describing the photoelectric effect
89
What is the purpose of MPPT?
It controls the IV parameters and will cause the inverter or charge controller to work on the point of maximum power on the IV curve.
90
(T/F) Arc flashes can be hotter than the sun?
True
91
What information do you need for figuring out the maximum string size?
Cold Expected Temp : Temperature Coefficient : Voc of PV module : Maximum Input Voltage for the Inverter
92
What is an ohm a unit of?
Resistance
93
The path of the sun is different at every latitude around the world?
False
94
What are the main components of an AC coupled battery system?
Solar Modules : Grid-Tied Inverter : Off-Grid Inverter / Charger : Batteries
95
For an off-grid system, what should you oversize?
PV array
96
What is another name for an interactive inverter?
Grid-tied
97
What is a dead load?
A permanent load on the roof. Anything that is installed on the roof and considered part of the building.
98
What are the components of PFAS?
Harness : Shock Absorbing Lanyard : Lifeline : Anchor
99
What would affect current more: The size of the solar cell or the temperature of the solar cell?
Size of the solar cell
100
What is a grid-tied battery-backup system?
Multimodal system that can operate as grid-tied or off-grid
101
What kind of inverter has PV source circuits connected to it?
String
102
Can state requirements be more lax than federal safety requirements?
No
103
What is Voc?
Open Circuit Voltage
104
What is direct radiation?
Radiation that comes directly from the sun
105
How do you calculate the derating for an entire system?
Multiply all derating factors together
106
What information do you need to find the minimum string size?
Hot PV Cell Temperature : Temperature Coefficient Vmp : Vmp : Inverter minimum input voltage
107
What happens to a system when it gets cold?
The voltage will get higher and could possibly damage the equipment.
108
What does a transformer do?
Changes high voltage and lower current to low voltage and high current
109
How many types of PV are there and what are they?
(6), Grid-tied * Stand-Alone * Hybrid * Grid-tied-Battery-Backup * Direct * Self-regulating
110
What type of ladder should you never use to get on a roof?
A Frame
111
What is the feature in an inverter that keeps it operating at MPP?
MPPT; Maximum Power Point Tracking
112
What is the average clearance between a roof and the PV?
3"-6"
113
How many watts are in 1 horsepower?
746W
114
What is the height at which you need fall protection?
6'
115
What kind of battery charging is done first and fast?
Bulk
116
What is the name of a battery system that works with or without the utility?
Grid-tied battery-backup system
117
The temperature rating of the the conductor can affect what?
Ampacity
118
What happens to a system when it's hot and the voltage gets low?
We run the risk of the system not turning on or poor productivity
119
What is the formula for calculating the production of a system?
AC kW system size x Derating x Insolation = Production
120
Bypass diodes sacrifice _____ for ______
Voltage : Current
121
What makes an AC module different than a module with a micro inverter attached to it?
The AC module was tested together
122
What is the purpose of a OCPD (Over Current Protection Device) and what will it do?
Protect equipment and conductors from over currents and will open the circuit if the current get high enough
123
What is a grounded conductor?
A conductor that is intentionally referenced to ground, but caries current
124
What required information must be on a PV module label?
STC Watts : Voc : Vmp : Imp : Isc : Maximum Series Fuse Rating : STC Conditions
125
A single axis tracker will face which direction in the morning?
East
126
What is a PV source circuit?
A group of DC PV modules connected together positive to negative
127
(T/F) PV systems have voltage going from the inverter to the grid?
True
128
What do series connections increase?
Voltage
129
What are other names for grid-tied battery backup systems?
Bimodal or Multimodal
130
Peak sun hours per day is often called what?
Insolation
131
What is diffuse solar radiation?
Sunlight that is scattered by being bounced off of objects
132
What is the optimal angle everywhere in the world except the tropics?
Slightly less than latitude.
133
How is solar power measured?
Power per unit area
134
This charging stage is for battery maintenance and has the highest voltage charge
Equalization
135
What will a group of cells not create when being bypassed?
Voltage
136
What is a controlled overcharge for maintenance of non-sealed flooded lead acid batteries?
Equalization charge
137
What type of relationship to current and voltage have in Ohm's law for resistance?
Proportional
138
Which type of solar panels have square corners and which one has round?
Multi (poly) has square and Mono has rounded
139
What is the hydraulic analogy of pressure?
Voltage
140
What is voltage drop?
When current goes through a wire and there are losses which happen when the wire heats up.
141
What is energy?
The amount of energy used
142
What is diffuse radiation?
Radiation that comes from bouncing off of clouds and the atmosphere
143
What is the part of the process where silicon is turned into a solar cell called?
Doping
144
What is another term for a DC-to-DC converter and what does it do?
Power Optimizer; converts voltage and current
145
How high above the roof should the top of the ladder be?
3'
146
What is another term for PSH (Peak Sun Hours)
Insolation
147
What is the best way to optimize for winter and fall production?
Latitude tilt plus 15
148
What type of wire connects modules together?
Use-2 wire or PV wire
149
What device measures direct beam solar radiation?
Pyranoheliometer
150
What is solar irradiance and how is it measured
Solar Power Per Area : watts per square meter
151
Ability to disconnect from the grid whenever the grid is down or not within specifications
Anti-Islanding
152
This is a piece of steel that is driven into the earth and is specially made for PV projects
Pile
153
Above 23.5 degrees south latitude is called what?
Tropic of Capricorn
154
In most of the US, what is the optimal degree for a south facing array?
30 degrees
155
What is the ability to carry wire called?
Ampacity
156
What is another term for grounding conductor and what does it do?
Equipment Grounding Conductor (EGC), it is a conductor that is not meant to carry current and connects (bonds) metal equipment together, so that there are no dangerous voltage differences.
157
What is a refractometer used for?
Checks battery acid with a test to see how light bends in fluid.
158
What is the solar window?
Every place the sun can be in the sky throughout the year for a given latitude
159
What is the UL listing for PV modules in North America?
1703
160
OSHA has state and federal requirements (T or F)?
True
161
(T/F) Grid-tied inverters do not need ground fault protection?
False
162
What is the formula for Energy?
Energy = Power x Time
163
Who produces the National Electric Code?
NFPA, National Fire Protection Association.
164
What is global radiation?
combined solar radiation from all types
165
What is the bottom element of a solar cell?
Boron
166
What is Vmp?
Maximum Power Voltage
167
A large inverter (usually in the MW range) that doesn't have PV source circuits connected to it is called what type of inverter?
Central
168
How does brightness affect performance?
Increases current
169
What is more efficient, higher voltage or lower voltage?
Higher Voltage
170
What is the purpose of Net Metering
Allows customers to get credit for the electricity they produce.
171
What are the main components in a PV source circuit?
Modules and Conductors
172
What kind of conductor is used for equipment grounding?
Green or bare copper
173
1000 Watts per square meter is called what?
Peak Sun
174
What is Voltage Drop?
When voltage and power are lost on a wire
175
What is NOCT?
Nominal Operating Cell Temperature
176
What is Isc?
Short Circuit Current
177
In general, PV open circuit voltage goes up how much for every 1℃ decrease in temperature?
one third of a percent or .3%
178
What are PV source circuit conductors?
Connects the PV to the inverter or the DC combiner.
179
What is the formula for batteries?
Ah x V = Wh
180
What is a self-regulating system?
A stand-alone system without a charge controller
181
What is the correct term for a string?
PV Source Circuit
182
What is the purpose of a blocking diode?
To preven reverse current
183
If there was a ground fault detected, where would the problem most likely be?
Pv source circuit (string)
184
Voltage and current are directly proportional to each other according to what law?
Ohm's
185
What is the best way to optimize for summer and spring production?
Latitude minus 15
186
The maximum power rating of the largest load of an off-grid system is limited by which of these two: The size of the inverter or the size of the charge controller?
The size of the inverter
187
What is the typical USA utility parameters for frequency?
60 hertz (60 cycles per second)
188
What are the units for: Voltage : Amps : Power : Energy
V : A : W : Wh
189
What is the chemical on the top layer of a solar cell?
Phosphorous
190
In California (East of the zero-degree isogonic line) the north needle of the compass will point in which direction?
East of true north
191
This type of system has interactive inverters that are used with battery inverters to charge batteries:
AC Coupled System
192
How much solar has been installed in the world by 2017?
Over 300GW
193
What are 3 things a large utility scale system might have as parameters to monitor?
Wind Speeds : Solar Cell Temps : Irradiance
194
The angle between the horizon and the sun is called what?
Solar Altitude Angle
195
Who discovered the photovoltaic effect?
Edmund Becquerel
196
What is a characteristic of an ungrounded inverter?
No DC grounded current carrying conductor
197
Albedo radiation is ______
Reflected
198
Storage battery overcurrent protection or a dc disconnect is not required for a voltage under _____
60V
199
What are the units that you measure apparent power?
VA
200
What is the current that would contract someone's muscle, and someone would not be able to let go?
10 to 20 mA
201
What is the NEC for?
Practical safeguarding of persons and property
202
An arc is caused by higher ____
Voltage
203
What is the most intense load on a PV system?
Wind
204
What is REC?
1,000,000 Wh
205
Which type of circuit has to have the wire and equipment sized based on at least 156% of short circuit current?
PV source circuits
206
What is the PVUSA test conditions temperature?
20C ambient
207
Which most commonly has a fuse in it in a modern PV system?
DC Combiner
208
How do you get a reading with a low current source and a clamp on ammeter?
Loop the wire around and divide by the number of loops
209
What is the slope of a 4:12 roof?
18 degrees
210
How do you find the roof degree if you are only given the rise/run?
Divide and Tan -1
211
Where would you find solar incentives on a state by state basis?
DSIRE website
212
What does NRTL stand for?
Nationally Recognized Testing Labs
213
What is the nominal voltage of a lithium-ion battery cell?
3.6V
214
What percentage of PTC is STC?
108%
215
What percentage of STC is PTC?
92%
216
(T/F) It is ok to have dissimilar metals touch each other?
False
217
What do you call the most common inverter used today and what was it called in the past?
functionally grounded that is non-isolated or transformer-less. Used to be called ungrounded
218
What is VA?
Apparent Power
219
What is VAR?
Reactive Apparent Power
220
What is the efficiency of solar panels converting solar energy into electricity?
20%
221
(T/F) Most PV systems are required to have dc ground fault protection for the
solar array?
True
222
What is the neutral called?
Grounded Conductor
223
The neutral is intentionally referenced to what?
Ground
224
Does an Equipment Grounding Conductor carry current?
No
225
Does temperature affect voltage or current more?
Voltage
226
What is irradiance more likely to affect?
Current
227
What do you call something if you divert excess electricity to a load that is not critical?
Diversion Load
228
What is a SREC?
Solar Renewable Energy Certificate
229
What does a feed-in-tariff do?
It is a performance based incentive that will give people back money for production of their solar system.
230
Explain net-metering
This is where you get credit for electricity you put back onto the grid.
231
What does MSDS stand for?
Material Safety Data Sheet
232
The only time you base wire sizing on a short circuit is with a _______
PV Module
233
How many strings of PV output circuits would require fuses in the DC disconnect?
3
234
What is a ground fault?
A ground fault is usually when a current carrying conductor that is insulated has a
violation of the insulation and current comes through where there should be insulation to
something that is grounded.
235
What does self commutated mean?
A commutation where the commutating voltage
| is supplied within the inverter.
236
What is C-Rate?
a way of explaining how much current a battery can safely
| deliver
