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Solar Panels

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Title: Solar Panels


1
SOLAR PANELS
Prepared by Thomas Bartsch Chief Fire Inspector
(ret) Past Chief of Department Valley Stream, NY
2
These are some of the Applicable Codes and
Standards in NY for Solar Panels
  • National Electric Code (NFPA 70) for
    Photovoltaic Systems
  • Mechanical Code of New York State for Thermal
    Systems
  • Plumbing Code of New York State for Thermal
    Systems
  • Residential Code of New York State
  • More restrictive local standards
  • UL Standard 1703, Flat-plate Photovoltaic
    Modules and Panels
  • UL Standard 1741, Standard for Static Inverters,
    Converters and Controllers for use in Independent
    Power Systems
  • IEEE 929-2000, Recommended Practice for Utility
    Interface of Photovoltaic (PV) Systems (approved
    in January 2000)

3
Solar CELLS
4
Solar Cells
  • What are Solar Cells?
  • Thin wafers of silicon
  • similar to computer chips,
  • much bigger,
  • much cheaper.

5
Solar Cells
  • Silicon is abundant (sand)
  • non-toxic, safe
  • Light carries energy into the cell
  • cells convert sunlight energy into electric
    current, they do not store energy.
  • Sunlight is the fuel.

6
Solar Modules
7
Modules
  • A group of cells make a module and a group of
    modules is called an array,
  • They generate electricity from sunlight, and
    have no moving parts,
  • Generally rated at between 125 and 200 watts
    each and produce between 24 and 48 volts of DC
    power,
  • When attached in a series, the voltage increases,

8
Modules
  • The National Electric Code (NEC) permits
  • for one- and two-family dwellings, PV system
    voltages up to 600 volts (DC),
  • for multi-family dwellings and other larger
    buildings, the PV system voltage can be even
    greater.
  • Most residences have from 15 to 40 panels,
  • Residential systems will generate anywhere from
    2,000 to 10,000 watts (two to ten kilowatts) in
    optimal sunlight conditions, at between 120 and
    600 volts DC,

9
Modules
  • There are different types of PV Modules
  • laminate/tempered glass- aluminum frame,
  • flexible laminate module and,
  • building integrated PV (takes the place of light
    weight concrete tiles),
  • solar shingles.

10
Glass with aluminum frame
Flexible laminate solar panels
11
Building integrated PV panels
Solar shingles
12
Solar Energy Systems
13
Solar Energy Systems
  • There are two common types of solar energy
    systems
  • Thermal systems,
  • Photovoltaic systems (PV).
  • Thermal systems heat water for domestic heating
    and recreational use (i.e. hot water, pool
    heating, radiant heating and air collectors)
  • typically have smaller solar panels than PV
    systems.

14
Solar Energy Systems
  • Thermal system.

15
Solar Energy Systems
  • Photovoltaic (PV) systems convert suns rays
    into electricity
  • some PV systems have batteries to store
    electricity,
  • other systems feed unused electric back into the
    grid.
  • Photovoltaic systems have three primary
    components
  • Modules
  • Inverters
  • and the Conduit
  • Panels are roughly 30x50 inches in area and
    weigh around 30-35 lbs each,

16
Solar Energy Systems
  • Photovoltaic

17
There are two types of PV systems Grid-connected
and Off-Grid (remote storage).
Grid connected system
Most installed PV systems are grid type.
18
Off Grid Photovoltaic System
19
Off Grid Systems
  • Can have wind-power, water-power and back-up
    generators to provide energy at night,
  • Extinguish battery fires with CO2, foam or dry
    chemical extinguishers, Dont cut into the
    batteries,
  • Keep in mind that if corrosive fumes come in
    contact with certain metals, they will produce
    toxic chemicals and explosive gases, wear PPE
    SCBA,
  • Careful with metal tools around batteries.

20
Mounting of THE System
21
Primary Concerns
  • That the mounting is structurally sound,
  • That the roof is properly weather proofed,
  • That electrical equipment is correctly installed
    according to applicable codes,
  • And there are Two main types of loads to
    consider
  • Dead Load
  • Wind Load

22
Mounting of Systems
  • The roof structure must be capable of supporting
    the dead load,
  • Most modern truss roofs are capable of handling
    the extra dead load provided that the roof is not
    masonry,
  • Masonry roofs often require a structural
    analysis or removing the existing product and
    replace it with composite in the area of the PV
    array,
  • Attachment method must be capable of keeping the
    PV array on the roof or relevant structure.

23
Mounting of Systems
  • Solar panels are installed either by
  • Stand mounting,
  • Flush mounting or,
  • Building Integrated arrays.

24
Mounting of Systems
  • Stand Mounts
  • the universal mounting system, used for ground
    and rooftop installations,
  • a grid-like system of supports of aluminum or
    steel that are affixed directly to roof joists,
  • or use non-penetrating concrete blocks,

25
Mounting of Systems
  • Flush Mounting
  • raised several inches to allow air circulation,
  • brackets are attached to the roof,
  • may be hard to see during the night,

26
Mounting of Systems
  • Building Integrated Arrays
  • serve as a structural element,
  • does reduce added weight,
  • photovoltaic shingles could be subject to high
    winds,
  • very difficult to see during the night or from
    the ground, Pre-Planning is very important!

27
Mounting of System
Examples of Building Integrated Systems
28
Solar panel Inverters, Disconnects Labels
29
Inverters and Disconnects
  • Modules are wired to an inverter, which converts
    the DC voltage to AC voltage and then feeds the
    electricity back into the main power distribution
    panel,
  • The inverter requires AC from the power company,
    shutting off the main electrical breakers also
    shuts down the inverter,
  • On new construction, inverters will most likely
    be installed within the building,

30
Inverters and Disconnects
  • Inverter can be mounted inside or outside of the
    building,
  • On Grid systems, inverter typically located near
    main electrical panel,
  • Off-Grid system, inverter either inside or
    outside of building,
  • Inverter may be found in a separate building
    that contains a generator or battery storage,
  • Also the inverter may be near devices or
    appliances the panels provide power to,

31
Inverters and Disconnects
  • Disconnects are often mounted on the inverter to
    shut off DC entering and AC leaving it,
  • These disconnects are primarily used by techs to
    service the inverter,

32
Inverters and Disconnects
  • DC disconnect does not shut off power in the DC
    conduit, it just keeps it from entering the
    inverter,
  • DC conduit is still live between the array and
    the inverter DC disconnect,
  • There is no rooftop disconnect to kill the DC
    power in the conduit.

33
  • Solar Inverter
  • PV arrays use an inverter to convert the DC
    power produced by the modules into AC,
  • For safety reasons a circuit breaker is provided
    both on the AC and DC side to enable maintenance.

34
Micro Inverter is connected at each module
35
Labels
  • Labels on the main service panel will indicate
    the PV system presence,
  • Labeling may be outside or inside of the main
    panel,
  • Look for the dedicated breaker for the inverter,
    it may be labeled Solar Disconnect or some
    variation thereof,
  • This breaker may be in a sub-panel, but there
    will always be a label on the main electrical
    panel stating presence of a second generating
    source on site,

36
Labels
  • Labels may be the only identifiers you might
    see, as the array may not be visible and the
    inverter may be in the fire.
  • LOOK FOR LABELS!!!!!!

37
LOOK FOR LABELS
38
Fire Department OPERATIONS at solar arrays
39
Fire Operations
  • PV systems can impact our FD operations and may
    also be part of the fire problem,
  • There is no single point of disconnect unlike
    standard electrical or gas service installations,
  • Severely damaged PV arrays are capable of
    hazardous conditions up to electrocution and can
    create unexpected electric paths, (i.e., metal
    roofs, gutters and array components),

40
Fire Operations
  • The black cable connecting each panel carries
    voltage and increases as it goes from panel to
    panel, DONT CUT THE CABLE OR REMOVE PANELS,
  • Do not cut into or walk across the PV modules or
    arrays,
  • Breaking protective glass could release all
    inherent energy in entire PV system,

41
Fire Operations
  • Always wear PPE and SCBA,
  • FF gloves and boots offer limited protection and
    are not be equal to electrical PPE,
  • Size-up
  • locate if panels are present,
  • get system information,
  • what type of system (Thermal or Photovoltaic),
  • locate electrical disconnects,

42
Size Up
This array can be seen from the street upon
arrival
This light source might help you see the array at
night
43
Size Up
You might see this one while doing your 360
What about this one at night?
44
Think you will see this one at night while doing
your 360?
Size Up
Conduit coming from the roof could be a clue,
look for it.
45
Fire Operations
  • Inform the IC that a system is present, the IC
    must relay this info to the responding units,
  • Use a STAY CLEAR approach
  • shut down as much as possible, Lock-out-
    Tag-Out
  • disconnect at the inverter, battery controller,
    and the battery bank as an extra measure of
    safety,
  • Remember PV Panels are 120 volts - 600 volts DC,

46
Usage of Tarps to cover the solar panels
47
Tarps
  • If operations require attempting to block light
    to the PV to protect FF, a tarp might be used,
  • Effectiveness of tarps to interrupt power
    generation varies with the type of tarp material,
  • Underwriters Laboratories (UL) research,1 have
    shown heavy, densely woven fabric dark black 4
    mil plastic reduce the power to near zero,

1 Firefighter Safety and Photovoltaic
Installations Research Project, Issue date
11/29/2011
48
Tarps
Research conducted by UL1, using only a single
tarp layer, to block illumination to the panels,
has shown
Green Canvas Salvage Cover, (test results were
3.2 open circuit volts and 0 short circuit amps)
were SAFE to use,
Heavy Duty Red Vinyl Salvage Cover, (test results
were 124 open circuit volts and 1.8 short circuit
amps) was an electrocution hazard,
49
Tarps
Blue plastic 5.1 mil all purpose tarp, (test
results were 126 open circuit volts and 2.1 short
circuit amps) was an electrocution hazard,
Black 4 mil plastic film, (test results were 33
open circuit volts and 0 short circuit amps) was
deemed SAFE to use.
50
Tarps
  • If light can be seen through the tarp, it should
    NOT be used,
  • A WET tarp may become energized if it contacts
    damaged PV equipment and conduct dangerous
    current,
  • The tarp must be secured down on all sides,
  • RISK vs REWARD, is it worth the risk to cover
    arrays, especially damaged arrays, to accomplish
    venting, overhaul, etc.???

51
Water and firefighting foam use on solar arrays
52
Water Foam
  • Water conductivity, voltage, distance and spray
    pattern effects electrical shock hazard,
  • UL1 research has shown that the use a fog
    pattern with a min of 10 degree cone angle, with
    a distance of 5 ft from a 1000 vDC, detected no
    current leakage,
  • A smooth bore nozzle required a 20 ft distance
    with the same 1000 vDC,
  • Because of its high conductivity, salt water
    should NOT be used on live electrical equipment,

53
Water Foam
  • Firefighting foams should NOT be relied on to
    block light on solar panels, as they proved to be
    ineffective,
  • Outdoor solar electric boxes are not water
    resistant to fire streams, they will collect
    water and present an electric shock,
  • No matter what the system, REMEMBER, applying
    water directly to any energized electrical
    equipment endangers FF to shock, turn off the
    main breaker at the electric panel.

54
Scene lighting
55
Scene Lighting
  • FD flood light trucks ARE bright enough to
    generate electricity, (UL research1)
  • Light from a fire, as far away as 75 feet was
    able to produce current, (UL research1)
  • Light from a full moon will not energize the PV
    cells,
  • Lightning is bright enough to create a temporary
    surge,

56
Scene Lighting
57
Scene Lighting
  • At night, apparatus roof rack lighting does not
    produce enough light to generate an electrical
    hazard,
  • If your department carries non-contact voltage
    detectors, they only detect AC voltage, not DC
    voltage.

58
Get the roof!!
59
Get The Roof
General
  • Remember, solar panels can impact our
    firefighting operations, especially PV systems,
  • Proximity to any fire involving photovoltaic
    system also brings with it an increased risk of
    inhaling toxic vapors, use your SCBA,
  • Should array become involved in a roof fire, use
    fog pattern, min 10 degrees,

60
Get The Roof
Safety
  • Shock is the PRIMARY firefighter danger,
  • Momentary contact with low DC voltages may
    produce
  • Continuous Shock,
  • Thermal Injury,
  • Ventricular Fibrillation,
  • Tripping and/or falling over raceway, etc.,

61
Get The Roof
Safety
  • Possible earlier roof collapse due to extra
    weight, especially under a heavy fire load,
  • Arrays can accumulate snow debris, added
    weight,
  • Hot water scalds with the Thermal system,
  • Electric shock, due to intentionally or
    inadvertently cutting into or through PV
    conductors, or raceways containing live PV
    conductors,

62
Get The Roof
Safety
  • The NEC permits
  • single conductor PV wire to be exposed in
    non-accessible outdoor locations, such as
    rooftops and ground mounted arrays,
  • when PV circuits are run inside a building, the
    conductors must be contained in a metal raceway,
  • when PV wires are run beneath a roof, they shall
    not be installed within 10 inches of the roof
    decking or sheathing, except where directly below
    the roof surface covered by PV modules and
    associated equipment,

63
Get The Roof
Safety
  • The 10 inch requirement is to prevent accidental
    damage from saws used by firefighters during roof
    ventilation,
  • It is important to also note that this
    requirement is new in the 2011 version of the
    NEC, and older installations may not have
    complied with this new requirement,

64
Get The Roof
Safety
  • Inhalation exposure, the manufacturing process
    includes the use of many hazardous chemicals,
  • Access for ventilation,

65
Get The Roof
Operations
  • Ventilate at the highest point over the fire
    without cutting through the PV array,
  • Flat roofs with complete PV coverage
  • horizontal ventilation with fog spray and/or
    Positive Pressure fan ventilation,
  • Fire and extreme heat will also affect the
    structure of the module. The high temperatures
    might cause the metal to warp and the modules to
    come loose from their anchor points, dangle or
    fall,

66
Get The Roof
Operations
  • Fire could cause damage to the wiring insulation
    and melt the aluminum mounting rail, resulting in
    possible loss of ground continuity, energizing
    the module frame and mounting rail,
  • Leave the scene in a safe condition, i.e., system
    damaged during a night fire, when exposed to
    sunlight, it begins to generate electric,

67
Now add metal roofing to the hazard
Get The Roof
68
Cut a hole, dont trip and dont inadvertently
pierce the panels, OK!
Get The Roof
69
There is no venting this roof with this
installation!
Get The Roof
70
SCBA
Get The Roof
Use a minimum 10 degree fog pattern
71
Not much room to vertical vent here!
Get The Roof
72
Get The Roof
Skylights, scuttles, smokes vents?
Positive pressure fans and/or fog nozzle to vent?
73
Get The Roof
Where are you going to perform roof ventilation
on this installation?
Hope the other side is clear!
74
Summary
  • Pre-Planning is essential,
  • If a system is present, notify IC and responding
    units,
  • When a sufficient light source is present,
    panels are energized,
  • Scene flood lighting can create dangerous levels
    of electricity,

75
Summary
  • Dont try to unplug or walk on the panels,
  • Dont intentionally break the panels or cut the
    conduit,
  • Contact with damaged systems are dangerous, even
    if the fire is out - stay away,
  • PV systems are the only electrical system that
    cannot be turned off by untrained personnel.

76
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