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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

What are Solar Cells?

 Thin wafers of silicon;  similar to computer chips,  much bigger,  much cheaper.

Solar Cells

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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, 7

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, 8

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 10

Solar shingles Building integrated PV panels 11

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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

Thermal system.

Solar Energy Systems

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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

 Modules   Inverters and the Conduit primary components;  Panels are roughly 30x50 inches in area and weigh around 30-35 lbs each, 15



Photovoltaic

Solar Energy Systems

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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

 Dead Load  Wind Load main types of loads to consider; 21

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, 24

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, 25

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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Examples of Building Integrated Systems

Mounting of System

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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, 29

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, 30

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, 31

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 34

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, 35

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), 39

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, 40

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, 41

Size Up

This light source might help you see the array at night This array can be seen from the street upon arrival 42

Size Up

What about this one at night?

You might see this one while doing your 360 43

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, 45

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 UL 1 , 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, 48

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,  UL 1 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, 52

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 research 1 )  Light from a fire, as far away as 75 feet was able to produce current, (UL research 1 )  Light from a full moon will not energize the PV cells,  Lightning is bright enough to create a temporary surge, 55

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, 59

Safety:

Get The Roof

 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., 60

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, 61

Safety:

Get The Roof

 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, 62

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, 63

Safety:

Get The Roof

 Inhalation exposure, the manufacturing process includes the use of many hazardous chemicals,  Access for ventilation, 64

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, 65

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, 66

Get The Roof

Now add metal roofing to the hazard 67

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

Use a minimum 10 degree fog pattern SCBA 70

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

Hope the other side is clear!

Where are you going to perform roof ventilation on this installation?

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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, 74

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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