Transcript Solar Panels - Dutchess Community College

SOLAR PANELS
Prepared by
Thomas Bartsch
Chief Fire Inspector (ret)
Past Chief of Department
Valley Stream, NY
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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)
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SOLAR CELLS
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Solar Cells
 What are Solar Cells?
 Thin wafers of silicon;
 similar to computer chips,
 much bigger,
 much cheaper.
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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”.
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SOLAR MODULES
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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,
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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,
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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.
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Glass with aluminum frame
Flexible laminate solar panels
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Building integrated PV panels
Solar shingles
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SOLAR ENERGY SYSTEMS
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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.
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Solar Energy Systems
 Thermal system.
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Solar Energy Systems
 Photovoltaic (PV) systems convert sun’s 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,
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Solar Energy Systems
 Photovoltaic
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There are two types of PV systems:
Grid-connected and Off-Grid (remote storage).
Grid connected system
Most installed PV systems are grid type.
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Off Grid
Photovoltaic
System
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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, Don’t 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.
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MOUNTING OF THE
SYSTEM
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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
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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.
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Mounting of Systems
 Solar panels are installed either by;
 Stand mounting,
 Flush mounting or,
 Building Integrated arrays.
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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,
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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,
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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!
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Mounting of System
Examples of Building
Integrated Systems
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SOLAR PANEL
INVERTERS,
DISCONNECTS & LABELS
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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,
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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,
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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,
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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.
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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.
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Micro Inverter is connected at each module
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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,
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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!!!!!!
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LOOK FOR LABELS
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FIRE DEPARTMENT
OPERATIONS AT SOLAR
ARRAYS
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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),
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Fire Operations
 The black cable connecting each panel carries
voltage and increases as it goes from panel to panel,
“DON’T 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,
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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,
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Size Up
This array can be
seen from the
street upon
arrival
This light
source
might help
you see
the array
at night
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Size Up
What
about this
one at
night?
You might
see this
one while
doing your
360
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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.
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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,
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USAGE OF TARPS TO
COVER THE SOLAR PANELS
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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”
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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,
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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.
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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.???
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WATER AND FIREFIGHTING
FOAM USE ON SOLAR
ARRAYS
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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 it’s high conductivity, salt water should
NOT be used on live electrical equipment,
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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.
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SCENE LIGHTING
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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,
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Scene Lighting
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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.
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GET THE ROOF!!
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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,
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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.,
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Safety:
Get The Roof
 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,
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Safety:
Get The Roof
 The NEC permits;
 single conductor PV wire to be exposed in nonaccessible 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,
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Safety:
Get The Roof
 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,
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Safety:
Get The Roof
 Inhalation exposure, the manufacturing process
includes the use of many hazardous chemicals,
 Access for ventilation,
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Operations:
Get The Roof
 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,
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Operations:
Get The Roof
 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,
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Get The Roof
Now add metal
roofing to the
hazard
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Get The Roof
Cut a hole, don’t trip
and don’t
inadvertently pierce
the panels, OK!
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Get The Roof
There is no venting
this roof with this
installation!
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Get The Roof
SCBA
Use a minimum 10
degree fog pattern
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Get The Roof
Not much room
to vertical vent
here!
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Get The Roof
Skylights,
scuttles, smokes
vents?
Positive pressure fans
and/or fog nozzle to
vent?
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Get The Roof
Where are you
going to perform
roof ventilation on
this installation?
Hope
the other
side is
clear!
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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,
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Summary
 Don’t try to unplug or walk on the panels,
 Don’t 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.
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THANK YOU
QUESTIONS?
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