NABCEP STUDY GUIDE

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Acronym for OSHA's Safety and Health Regulations for Construction

29 CFR Part 1926

Central Inverters

30- 50 kW systems interconnected to 3-phase grids. Great for homogeneous PV arrays

Maximum Power Current (Imp)

Current corresponding to Pmp

Response to Irradiance

Current is directly proportionate to irradiance

UL1703

Safety Standard for Flate Plate Photovoltaic Modules and Panels

Equipment Grounding

EGC Connects non-current carrying metal parts to ground. Achieved with a GROUNDING CONDUCTOR

What are coloring requirements for PV Source Circuit

It can be black as long as the termination is appropriately marked off with the correct color.

Average daily amp hours required

The amount of battery energy (amp-hours) needed to run the loads for one day.

Surge

The increased current draw for a very short time span when certain loads such as a motor are starting.

Voltage Drop % Equation For AC

Voltage Drop %= (0.2)(D)(System Imp)(Resistance) ________________________ (Inverter Output Vnom)

Voltage Drop % Equation For DC

Voltage Drop %= (0.2)(D)(System Imp)(Resistance) ________________________ (System Vmp)

Maximum Power Voltage (Vmp)

Voltage corresponding to Pmp

Determine Number of roof attachments required per row of modules

# of attachments = Lp/Plag Wherein: Lp = (ft^2 of row)*(wind uplift rating) Plag = (Pull out strength per inch)*(# threaded inches)

Stand-alone systems

(Also known as "off grid" systems) Not connected to the utility and are the primary energy source for the connected electrical loads, which may be ac and/or dc

Valve-regulated lead-acid (VRLA)

(Also known as sealed lead-acid) Batteries that do not allow access to the battery's electrolyte, but have non-openable valves that allow any excess pressure to escape.

One Amp is....

1 columb per second

Color Options for Grounded Conductors

1) Continuous White 2) Continuous Grey 3) Three Continuous White Stripes

Determining Max Voltage of PV System Method #1: Manufacturer's Temperature Correction Factor (The Percentage Method)

1) Convert Temperature Coefficient % to number Ex: Temp Coefficient is symbolized as @Voc @Voc = - 0.37%/C = -0.0037/C 2) Find Temperature Correction Factor TCF = 1 + [@Voc x (Temp Low - Temp Rated)] = 1 + [ (-0.0037/C) x (-12C - 25C) ] = 1 + (-0.0037 x -37) = 1 + 0.137 TCF= 1.137 3) Then use correction factor to find Max System Voltage (Voc) x (# of Modules wired in series) x (Voltage Correction Factor)

7 Requirements for Load Side Connections

1) Each inverter must have a dedicated disconnect and overcurrent protection device. 2) Sum of Ampere Ratings Of OCPD connected to a busbar does not exceed 120% of Busbar rating. 3)** Interactive Inverters must be interconnected on the line side of all ground-fault protection devices. ** 4) All distribution equipment must have labels 5) Circuit breakers used for inverter connections must be suitable for backfeeding. 6) Fastening is not required for breakers fed by inverters 7) If the sum of the OCPD ratings is greater than 100% of the busbar rating than the PV breaker must be on the opposite side of the utility power supply in the MDP.

Formal Equation for Row to Row Spacing

1) Find Spacing between rows (without Azimuth Adjustment) Tan(Sun Alt Angle) = (Height of Row)/(Spacing between Rows) 2) Multiply Spacing by COS of Azimuth Difference from Array COS(Azimuth Diff) x (Spacing Between Rows) = ANSWER

Acceptable colors for EGC

1) Green 2) Green with yellow stripes

Insulation Resistance Testing

1) Isolate circuits (leave bonding and grounding in tact) 2) Remove surge suppression equipment from circuit. 3) Connect the positive and negative homeruns. Connect this to the Positive Terminal of Insulation Tester 4) Connect Negative Terminal of Insulation Tester to Array Grounding Point. 5) Apply a test voltage of 500 V 6) Measure resistance in MEGA OHMS If a fault exists, resistance measurements will decrease significantly.

Supply Side Connection Requirements

1) Must have a service rated disconnect and a OCPD rated for at least 60 Amps 2) Fcuk it

Tests to be done during commissioning

1) Test AC Circuits for Continuity, phasing, voltage 2) Test DC circuits for continuity of grounding conductors 3) Verify correct DC polarity 4) Test String open circuit voltage 5) Test String Short Circuit Current 6) Verify System Functionality 7) Test insulation resistance for PV arrays source and output circuits.

Two factors that increase voltage drop

1) increasing current 2) long homerun lengths

Minimum Size Wire to be used with 30, 40 & 60 Amp OCPD

10 AWG

How many Amps will freeze your muscles

10 mA

Minimum Size Wire to be used with 20 Amp OCPD

12 AWG

What percentage of young worker workplace deaths are caused by electrocution?

12%

Minimum Size Wire to be used with 15 Amp OCPD

14 AWG

Sizing Wire (page in NEC)

149

Acceptable range for voltage drop

2% to 5% of operating voltage

Where in NEC is Ground Wire Size Specified based on OCPD

250.122 .....but you need #6 for module frames and rails

Working Clearance for Electrical Equipment

3 foot clearance from front Width = 30 inches or width of equipment See NEC 110.26

NEC recommended voltage drop

3% to 5% Found in the "Branch Circuits Section"

At what operating voltage is voltage drop not such a big deal

300 V

If grounding electrode is encased in concrete the minimum size AWG is...

4 AWG

At what operating voltage is voltage drop a huge concern

48 V

How many workers are electrocuted each week

5

What is the minimum size EGC that can be ran outside of conduit

6 AWG

One columb is

6.24 billion billion electrons 6.24 x 10^18

Frequency of american electrical system

60 Hertz/second

Where is Maximum Photovoltaic System Voltage found in the NEC

690.7

How many amps will cause an inefficient heartbeat?

75 mA

Requirements for Feeder Taps (page in NEC)

92

1000 Watts per Meter^2 Equals ....(feet^2)

92.9 watts per foot^2

Solar Radiation

???Electromagnetic radiation from the sun???

Ballasted Mounting Systems

Used for large scale flat commercial roofs.

Grounding Electrode (GE)

A conducting object, often a rod, ring, or plate, establishing a direct connection to earth

Ungrounded conductor

A current-carrying conductor that has no connection to ground, and therefore is normally energized with reference to ground and the grounded conductor. Whether ac or dc, and regardless of polarity, ungrounded conductors must be any unique color other than white, gray, green, or bare.

Grounded conductor

A current-carrying conductor that is intentionally connected to earth ground at one point to create a zero-voltage reference. Whether ac or dc, and regardless of polarity, grounded conductors must be white or gray.

Ground fault protection device (GFPD)

A device that detects whether fault current is being carried by the equipment grounding conductors and can disable the system

Battery bank

A group of batteries wired in series and/or parallel wiring configurations to a specific voltage and capacity

UL1741

Used in conjunction with IEEE1547

Equipment grounding conductor (EGC)

A non-current-carrying conductor used to connect the exposed metal parts of equipment, modules, and other metallic items to the grounding electrode conductor or system ground

Backed-up load panel

A subpanel in a grid-tied with battery back-up system that can be isolated from the utility grid and receive power from the battery bank during power outages.

Surge protection device (SPD)

A voltage actuated device designed to safeguard equipment from electrical surges and spikes, including those caused by lighting

You are designing an off-grid PV system for a home with a dirt floor crawl space. The battery bank has 2/0 conductors feeding the DC panel. The charge controller has #4 conductors feeding the battery bank. Size the grounding electrode and grounding electrode conductors for a 150 amp rated AC panel being fed by four 3600 watt inverters configured for 240 volt output. a. 2 ground rods 6' apart with a #6 GEC c. Concrete encased electrode with #4 GEC b. 2 ground rods 6' apart with a #8 GEC d. 1 ground rod with 2/0 GEC

ANSWER: A 3600 x 4 = 14400 ÷ 240 = 60 amps x 125% = 75 amps The OCD will be 75 amps Table 310.15(B)(16) shows #4 to be rated for this ampacity. Art 690.47(C)(2) allow for a common grounding electrode with the grounding electrode conductor sized according to 250.166. If we size the grounding electrode conductor for the AC side Table 250.66 shows a #8 grounding electrode conductor to be adequate. The smallest grounding electrode that can be installed is a pipe or ground rod. A second grounding electrode installed at least 6' away form the other is required if the ohms to ground is more than 25 ohms; (it always is). 250.166 states that the DC grounding electrode conductor be no smaller than the largest conductor serving the system (2/0). Although an allowance is made if the AC grounding electrode is a rod or pipe. In this case the grounding electrode conductor is not required to large than a #6 cu.

The residence has a 200 amp service and is grounded with a concrete encased electrode. What size grounding electrode conductor is required to be installed from the inverter to the grounding electrode system for a 5kW residential inverter fed by a 6kW PV array with #10 output conductors? a. #8 copper c. #4 copper b. #6 copper d. #4 tin coated aluminum

ANSWER: A Art. 250.166 requires the grounding electrode conductor to be no smaller than the largest conductor feeding the system and no smaller than #8.

The PV array of a grid-interactive PV system is ground mounted and located more than 6' away from the existing premises grounding electrode system. The existing grounding electrode system is a concrete encased electrode. The PV array combiner is fed with #12 PV wire and the output conductors are #1 copper conductors running underground in PVC conduit over to the inverter location by the premises wiring. You have galvanized metal posts for array supports and decide to add a grounding electrode 6' away from the poles. What size bonding conductor must be run from the ground rod to the main premises grounding electrode? a. #1 c. #6 b. #10 d. #4

ANSWER: D Art 690.47(C)(1) refers to the need for DC grounding. This could either mean a total DC system or a DC to AC system that is more than 6' from the existing premises grounding electrode. Art. 250.166(C) allows for the grounding electrode conductor to be no larger than the electrode selected (pipe and rod). Art. 690.47(C)(1) also states that the grounding electrode can be no smaller than the largest grounding electrode conductor of either system.

52. Which of the following AC systems can a single phase 208/240/277 volt inverter not be connected to. a. Residential 120/240 volt 1 phase transformer c. Commercial 480 volt Wye transformer b. Commercial 120/208 volt Wye transformer d. Commercial 480 volt Delta transformer

ANSWER: D The 480v delta does not have a neutral conductor.

What is the smallest wire allowed by NEC

AWG 14

Load Side (in reference to MDP)

After the MDP

Inverter Bypass Switch

Allows for grid/generator to power loads when inverter needs maintenance

Grounding conductor

An equipment grounding or grounding electrode conductor. It must be green, green with yellow stripes, or bare.

Ground fault

An unintentional, electrically conducting connection between a current-carrying conductor of an electrical circuit and the normally non-current-carrying conductors, metallic enclosures, metallic raceways, metallic equipment, or earth.

Rough guide for array-inverter sizing

Array = Inverter *1.2

Where is interconnection discussed in the NEC

Article 705

Equation for sizing battery system

Avg. Amp Hours/day = (Avg daily load)/(Inv eff)/(DC System Voltage)

Considerations for AC wire sizing

Based on continuous current calculation (Output/240*1.25) However, must make sure breaker regulations are also met. See NEC 240.4(D)

Flooded lead-acid (FLA)

Batteries that have cell caps that can be opened, allowing access to refill the cells with distilled water periodically.

Multi-Mode Inverter

Battery based inverters that interact with the grid. When Battery is charged, excess Power goes to the grid.

Supply Side (in reference to MDP)

Before the MDP

Passive Cooling based on Mounting System

Best: Rack Mount So-S0: Common Standoff (best at 3-6 inch roof clearance) Worst: Direct Mount

What colors are utilized by a 277 volt system?

Brown-Orange-Yellow

Load shedding

Can be programmed into some systems so that when the battery voltage reaches a certain level, less critical loads are turned off, allowing the more important loads to continue to operate.

Inverter/chargers

Can function both an inverter--changing dc electricity to ac electricity-- and as a battery charger--taking ac electricity and converting it to dc electricity to charge a battery bank.

Where are Conduit Requirements found in the NEC

Chapter 3 your mother ****er

Pulse width modulated (PWM)

Charge controllers regulate battery charging by switching the PV array on and off hundreds or thousands of times a second to taper the array output current.

Module Maintenance

Check For 1) De-lamination 2) Moisture or corrosion within the modules 3) Discoloration within the modules 4) Degradation of Solar Bonds at internal cell connections - This can lead to hot spots, burning through back of module, fire, death and lawsuits.

System grounding

Connecting one current-carrying conductor of a system to ground at one point to create a reference to zero

System Grounding

Connects a current carrying conductor in an electrical system to ground Achieved with a GROUNDED CONDUCTOR

Inter Row Spacing

D = 3H D is distance between rows H is height of module

Solar Altitude Angle

Defines the Suns elevation above the horizon.

Solar Azimuth Angle

Defines the direction of the sun's horizontal projection relative to a point on Earth.

Low voltage disconnect (LVD)

Disconnects loads from the battery bank at a certain voltage in order to prevent over-discharging and damage to the batteries.

Bonding

Electrically connecting metal parts together so that they stay the same voltage.

In regards to explosion concerns, what must be installed to vented battery cells

Flame arrestor

Four Types of Electrical Injuries

From Direct Contact 1) Electrocution (death) 2) Electrical Shock 3) Burns From Indirect Contact 4)Shock

Grounding Electrode Conductor

GEC Connects the Grounding System Electrode to the Equipment Grounding Conductor or the System Grounding Conductor A GEC that is #6 AWG can be used outside of conduit Anything Smaller than #6 must be put inside of conduit.

Inverter GFDI

GFDI = Ground Fault Detection Interrupter Grounded PV Inverters (residential ) have fuses that are 0.5 - 1 amp Grounded PV inverteres (commercial) have fuses that are 2-4 amps Ungrounded systems have none fused GFDI that shut the inverter off.

Bifacial Module

Generate energy from both sides of module

Sine Wave Explanation

Go **** yourself

Where do you find specific properties about various conduits?

Go to Appendix in NEC (all are clearly labelled).

Deep-cycle batteries

Have the ability to be discharged up to 80 percent and are commonly used in RE systems

Proper ladder set up

Horizontal distance from the top support to foot of ladder is 1/4 length of working length (hypotenuse).

Ohm's Law

I = V/R Ohm was from Transylvania.... I Vill Remember!!! Most common application is solving for Resistance: R = V/I .....Remember Vill I?

When is a charge controller needed?

If .... (Maximum charge rates for the PV array) x 1 Hour = 3% of the battery nominal amp-hour capacity.

Where can you find Resistance / kFt

In the NEC Chapter 9 Table 8

Stand-alone dc load-only systems

Include a PV array, charge controller, battery bank, and dc load(s)

What do you do if battery fault current is higher than over current devices?

Install current limiting fuses

Output of inverter for a 3 phase wye 208 V transformer

Inverter Rating / 208 / [Sqroot(3)] **1.73 is the square root of three**

Safety Precaution: Tagging

Labeling deactivated controls, de-energized equipment, and circuits at all points where they can be energized. Must identify the circuits being worked on.

Array Cooling based on Module Orientation

Landscape orientation provides better cooling than Portrait orientation

Voltage limitations for battery installations in dwellings

Less than 50 Volts

Determine Solar Altitude Angles for Region

Maximum and Minimum Solar Altitude Angles are determined by the Winter and Summer Solstice. The equation is as follows: 90 - (Latitude) + Solar Declination Example: At Latitude 40 the range would be determined as follows SUMMER SOLSTICE 90 - 40 + 23.45 = 73.45 WINTER SOLSTICE 90 - 40 + (-23.45) = 26.55 ALTITUDE ANGLE RANGE FOR 40 Deg LAT 73.45 to 26.55

DC input voltage

Must match nominal battery voltage, which is typically 12, 24, or 48 Vdc.

Required precautions when dealing with electrical shit can be found in what tantalizing document

NFPA 70E - Electrical Safety in the Workplace

Do bypass diodes function while getting Voc Readings?

No

How far can safety nets be deployed?

No more than 30 ft below where work is being performed

Power clipping

Occurs when the array power is greater than an inverter or charge controller can output, and the device will decrease the power output.

Shallow-cycle batteries

Only meant to be discharged 10 to 20 percent, and are not suitable for most RE systems

Who unlocks a Lock-Out breaker?

Only the person who applied it

Interactive PV Systems

Operate in parallel and are interconnected and synchronized with the electrical grid.

What Size Battery System Does Not Require Grounding?

Over 48 V - You are not required to have a grounded current carrying conductor if.......... 1) The PV Source and Output Circuits Must have a grounded current carrying conductor (or meet requirements for ungrounded PV systems) 2)DC and AC load circuits for the system must also be solidly grounded. 3) Both Positive and Negative Ungrounded Battery Circuit Conductors must have a switched disconnect means and overcurrent protection. 4) GFDI is required

What gases are produced during battery charging?

Oxygen and hydrogen

Where do you find information about Battery System requirements in the NEC?

P. 360 Article 480.5

Where do you find working clearances in the NEC

Page 38 Table 110.26(A)(1)

Safety Precaution: Lockout

Physically locking the power source disconnect in the OFF position with a padlock

Point of Connection

Point where distributed generator (PV System) interfaces with the utility system

In regards to explosion concerns, what must be installed to sealed battery cells

Pressure relief valves

Average daily load

Refers to the average amount of energy used in a day; this value is critical for off-grid sizing.

Agonic Line

Region where magnetic declination is zero

Charge controllers

Regulate how much energy is sent into the batteries to ensure that the batteries do not get overcharged. In a PV system, the charge controller is located between the array and the batteries

Ungrounded systems

Require equipment grounding but do not have system grounding; there is no dc current

Three types of eye protection

Safety Glasses Goggles Face Shield

29 CFR Part 1926 Subpart X

Stairways and Ladders

IEEE 1547

Standard for Interconnection of Distributed Resources with Electrical Power Systems Focus is distributive resources with capacity less than 10 MVA.

SLI Battery

Stands For: Starting, Lighting & Ignition Battery. This can deliver high discharge currents but is damaged during frequent and deep discharges (seldom used in PV)

VRLA Batteries

Stands For: Valve Regulated Lead Acid Batteries Have immobilized electrolyte in gel form. They are spill proof and do not require electrolyte maintenance. (Most expensive though and less tolerant of overcharging.)

Adjustment Factors (Going from System Size to Expected Performance)

Start with System Size W (DC) @ STC 1) Temperature Derating = 1 - [(Temp - 25) x (Temp Coefficient)] 2)Irradiance Rerating = (Irr / 1000 W per M2) 3) Inverter Efficiency 4) Mismatch/Wiring 5) Soiling

What are the requirements for EMT support

Support every 10' with an additional support 3' from Box

Voltage drop / wire size

Systems operating under 100 votes will determine wire size based on voltage drop

Grid-tied with battery back-up systems

Systems that can sell excess energy to the utility grid and that have batteries to power backed-up loads during a utility outage.

Integral Mounting Systems

Systems where modules are integrated into the roofing or building exterior

Energy (definition)

The TOTAL amount of power used over time **Think Total Income**

Magnetic Declination

The angle between magnetic north and the true geographic North Pole.

Equipment grounding

The bonding to ground of all non-current-carrying exposed metal parts that may become energized in a fault situation

Grounding electrode conductor (GEC)

The conductor used to connect the grounding electrode or grounding electrode system to the system grounded conductor, to the equipment grounding conductor, or both

Ground

The earth

Inverter rated maximum continuous ac output power

The highest power (watts) that the inverter can provide, which in an off-grid system must be large enough to operate all loads that could run simultaneously.

Solar Noon

The local time when the Sun is at it's highest point in the sky and crossing the local meridian (line of Longitude). It's rarely noon. Best way to find it is to find the projected sunset and sunrise time and then determine the midway point.

What is a cathode

The negative side of a diode

Days of autonomy

The number of consecutive days a battery can provide energy to loads without being recharged

Maximum Power Point (Pmp)

The operating point on an IV curve where the product of current and voltage is at a maximum

Depth of discharge (DOD)

The percent of battery capacity that been used. 100% DOD indicates an empty battery

State of Charge (SOC)

The percentage representing the amp-hours remaining in the battery bank. 100% SOC indicates a full battery

What is an anode

The positive side of a diode

Solar Irradiation

The suns radiant energy incident on the surface of a unit area. Often expressed in kWh/m2 aka Solar Insolation

Solar Insolation

The suns radiant energy incident on the surface of a unit area. Often expressed in kWh/m2 aka Solar Irradiation

Solar Irradiance

The suns radiant power incident on the surface of a unit area. Often expressed in W/m2

If the voltage drops on one module what happens to the string?

The voltage of all modules are averaged

Albedo Radiation

This is reflected radiation

Grounded

To be intentionally connected to earth through a ground connection, at a reference point of zero volts or zero potential

Hard Hats

Type 1: Protects from fallings objects Type 2: Protects from falling objects and side swipes Class G: Reduce danger of contact with low voltage conductors (proof tested for 2,200 Volts) Class E: Reduce danger of exposure to high voltage conductors (proof tested for 20,000 V) Class C: Provide no protection from electrical conductors.

What is the exception to the system grounding rules in the NEC

Ungrounded PV arrays that meet all requirements in 690.35

Safety Precaution: Working with Energized Equipment

Use proper PPE 1) Class G Hardhat 2) Electrical Hazard Rated Footwear (EH) 3) Face Shields 4) Gloves 5) Flame resistant clothing

When is hearing protection required

When noise exposure exceeds 8 hr weighted average at 90 dBa or above. Must monitor noise levels when 85 dBa is reached.

When is a battery system considered grounded

When the PV Power Source is Grounded

Stacking inverters

When the output of two or more inverters is coupled in series to produce a higher output voltage.

When are PV source circuits required to be fused?

When the series fuse rating of the module is less than the Isc of the modules * number of modules wired in series.

Equation for Finding Wire Size based on Voltage Drop

Wire Resistance (Ohm/kFt) = (Voltage Drop)(System Vmp) _____________________ (0.2)(D)(Max Power Current) **NOTES** Select wire with a resistance lower than the calculated value to achieve the desired voltage drop

Equation for Incident Angle

Zenith Angle - roof pith

Question about altitude derating... Your company has installed two identical commercial 100kW systems in two very different locations. One is located in Georgia at 1000' altitude the other is located in Montana with an altitude of 8000'. What size adjustment should be made to the installation in Montana compared to the one in Georgia?

a. The inverter should be 20% larger c. No change is necessary. b. The inverter should be 20% smaller d. The inverter should be 50% larger ANSWER: A 7000' ÷ 33,000' = .212 21.2%

What is peak sun hours expressed in?

kWh/m^2/day

GEC Size when connected to rod, pipe or plate electrodes

page 128 Does not need to exceed 6 AWG

Where do you find information about Junction and Pull boxes in terms of minimum sizes....

page 183 in NEC

When factoring in module mismatch what should you derate?

roughly 1.5% or half the negative side

Inverter Efficiency

(AC Power Output) / (DC Power Output) Example: 95000W AC Output 10000 W DC Input Creates a 95% efficient inverter0

Determining Max Voltage of PV System Method #3: Use NEC Temperature Correction Factor

(Voc) x (# of Modules wired in series) x (Voltage Correction Factor based on NEC) [NEC Table 690.7]

Acceptable Sizes for Overcurrent Protection Devices

1) Increments of 1 Ampere in between 0-15 Ex: 1,2,3.....15 2)When Amp > 15, they shall always be rounded up. Allowable sizes can be found in 240.6 (A). Ex: 20, 25, 30, 35, 40, 45, 50,60,70,80,90,110,125,150 etc

Order of Circuits

1) PV Source Circuit 2) PV Output Circuit 3) Inverter Input Circuit 4) Inverter Output Circuit

1 Megawatt = ?

1,000,000 Watts (Myyyyyyyyyyyy..........KingHenrysDrunkenUncleDrinksChocolateMilk

Peak Sun

1000 W/m2 (Typical for sea level, facing the sun on a clear day at solar noon)

STC - Standard Testing Conditions

1000 W/m2 1.5 Atmosphere 25 Degree Celsius cell temperature

How many employees can a company have before OSHA requires company to maintain a record of occupational injuries and illness.

11 or more employees

Utility Scale Inverters

500 kW to 1 MW and Higher. For Solar Farms.

Sun Path Diagram

A graphical representation of the Sun's altitude and Azimuth angles over a given day of the year (for a specific latitude)

Motive Power

A lead-acid battery designed for use in deep discharge applications (commonly used with PV) A.K.A: A Traction Batter

Traction Battery

A lead-acid battery designed for use in deep discharge applications (commonly used with PV) A.K.A: A motive Power

Battery Capacity

A measure of the stored energy that a battery can deliver under specific conditions. Measured in Amp Hours A nominal 6 volt battery rated for 220 Ah stores 1.32 kWhs Usage capacity is always less than the rated battery capacity due to discharge rate, cut-off voltage, temperature and age of the battery.

Inverter Output Circuit

AC conductors from inverter output to utilization load. To find maximum current: 1) check inverter spec sheet. If not listed..... 2) (continuos power rating) / (nominal AC voltage)

Standoff Mounting Systems

AKA Flush Mount. The mounting system that Dan Whitson uses

Zenith Angle

Angle of the sun in comparison to the zenith (90 degrees) Opposite of Altitude Angle (added together the two should be 90)

Peak Sun Hours

Average daily amount of solar energy received on a given surface. Equated to number of hours that the solar irradiance would need to be at peak level of 1 kW/m2 to accumulate the total amount of daily energy received.

Conductor Size

Circuit conductor size will be the larger of the two: 1) Max Current, as defined in 690.8 (A), multiplied by 1.25 2) Max Current, as defined in 690.8 (A), after conditions of use have been applied.

Contour Chart

Compares the effects of array orientation on the amount of Solar energy received.

Inverter Input Circuit

Conductors from DC disconnect to inverter Max current should be same as PV OUTPUT CIRCUIT

PV Source Circuits

Conductors from modules to source circuit combiner box To find maximum current: Isc x 1.25

PV Output Circuit

Conductors from source circuit combiner box to DC disconnect. To find maximum current: Sum of all Max currents wired in Parrallel.

Discharged Battery

Converts chemical energy to electrical energy

Charged Battery

Converts electrical energy to chemical energy

29 CFR Part 1926 Subpart K

Electrical

Bypass Diode

Electrical check valves that permit flow of current in one direction only. Prevent cells from overheating when a part of module is shaded.

Energy (Equation)

Energy (Wh) = Avg. Power (W) x Time (hr)

29 CFR Part 1926 Subpart M

Fall Protection

What is leading cause of death in construction industry

Falls

Fall Equinox

First Day of Fall (September 21st)

Spring Equinox

First Day of Spring (March 21st)

Summer Solstice

First Day of Summer (June 21st)

Winter Solstice

First Day of Winter (December 21st)

Specific Gravity of a Charged Lead Acid Battery

Fully charged the specific gravity is 1.26 to 1.28 at room temperature. This may be increased for lead acid batteries in cold weather applications and decreased for warm climates (to conserve battery life).

29 CFR Part 1926 Subpart C

General Safety and Health Provisions

Power Conditioning Components

Inverters, Charge Controllers, Maximum Power Point Trackers

Pole Mounted Systems

Manufactured racks are attached to a pole (ground mount)

Open Circuit Voltage (Voc)

Max DC voltage on an IV curve. Operating Point for a module with no connected load. Independent of PV cell area. Has direct correlation to operating cell temperature.

Short Circuit Current (Isc)

Max current on an IV curve Operating Point for a module with no connected load. Directly proportionate to solar irradiance

Allowable Depth of Discharge

Maximum limit of battery discharge in operation. Usually limited to no more than 75% to 80% for deep cycle batteries. Must be limited to protect Lead Acid Batteries from freezing in extremely cold conditions.

When is OSHA poster required?

Must be displayed Within 8 hours of an accident that results in hospitalization or death of 3 or more employees.

29 CFR Part 1926 Subpart D

Occupational Health and Environment Controls

Stand Alone PV Systems

Operate independently of other electrical systems (ie the Grid)

29 CFR Part 1926 Subpart E

PPE

State of Charge

Percentage of available battery capacity compared to a fully charged state

Depth of Discharge

Percentage of capacity that has been removed compared to a fully charged state

Power Density (Equation)

Power Density of Module = Watts of Module / Square Footage of Module Ex: 175 W module that is 14.4 Square Feet has power density of 12.2 W/sf

Power

Power is the RATE of transferring energy. Expressed in Watts. *Think of an hourly wage**

Power Density (Define)

Power per area of measurement (Watts/Square Foot)

Rate of Charge (or Rate of Discharge)

Ratio of the nominal battery capacity to charge (discharge) time period in hours. EX: A nominal 100 Ampere-Hour batter discharged at 5 amps for 20 hours is considered a C/20 or 20-hour discharge rate. The higher the discharge rate > the less capacity can be withdrawn The lower the temperature > the less capacity can be withdrawn

IV Curve

Represents infinite number of current and voltage operating point pairs for a PV device at a given solar irradiance and temperature operating condition.

Declination

The angular distance of a point north or south of the celestial equator. *The sun varies + or - 23.45 degrees throughout the year

Array Tilt Angle

The array tilt angle is the angle between the array surface and the horizontal plane

Array Azimuth Angle

The direction an array surface faces based on a compass heading or relative to due south

Solar Window

The range of Sun paths for a specific latitude between Winter and Summer solstices. What you see on the Suneye

Specific Gravity

The ratio of the density of a solution to the density of water.

Requirements for PV Module Labels

There are 8 Requirements: 1)Polarity of Terminals 2) Maximum Overcurrent Device Rating for Module Protection 3) Isc 4)Voc 5)Vmp 6)Imp 7) Maximum Permissible Systems Voltage 8) (Pmp) Maximum Power

29 CFR Part 1926 Subpart I

Tools, hand and Power

Balance of System Compontents

Used to conduct, distribute and control flow of power in the system. (Everything besides modules and inverters).

Response to Temperature

Voltage is directly related to temperature. Temperature Coefficients are used to predict drops and hikes in voltage based on temperature variance during testing conditions. Usually, the temperature coefficient is as follows: -0.4% per Degree Celcius (however, you should use what's on the module spec sheet)

Where are OSHA Standards found?

Volume 29 of the U.S. Code of Federal Regulations (29 CFR)

Equation for Peak Voltage of Pure Sine Wave

Vpeak = Vrms x Squareroot(2)

Positive Magnetic Declination

When Magnetic North is East of true north.

Negative Magnetic Declination

When Magnetic North is West of true north.

When do you need an equalizing charge?

When there are inconsistent specific gravity readings between cells in flooded lead-acid batteries.

When is fall protection required?

When you can fall 6 feet or more


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