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SOLAR SYSTEMS

BASICS

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 ARRAYS There are two common types of solar energy systems;

thermal systems, photovoltaic systems (PV).

Thermal systems heat water for domestic use, heating, and recreational use (i.e. hot water, pool heating);

typically have smaller solar panels than PV systems.

Photovoltaic (PV) systems convert sun’s rays into electricity;

some PV systems have batteries to store electricity, other systems feed unused electric back to the grid.

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Primary Concerns

Mounting of the system structurally sound.

Roof properly weather proofed.

Electrical equipment correctly specified and installed according to code.

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Mounting of System

Two main types of loads to consider;• Dead Load• Wind Load

Structure must be capable of supporting dead load and attachment method must be capable of keeping the PV array on the roof or relevant structure.

Most modern truss roofs are capable of handling the extra dead load provided that the roof is not masonry.

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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.

Mounting continued

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What are Solar Cells?

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

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Silicon is abundant (sand);- non-toxic, safe

Light carries energy into cell;- cells convert sunlight energy into electric current, they do not store energy.

Sunlight is the “fuel”.

SOLAR ARRAYS continued

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SOLAR ARRAYS continued

Thermal system.

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SOLAR ARRAYS continued

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Photovoltaic

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Photovoltaic Systems

Photovoltaic systems have three primary components;• Modules• Inverters• and Conduit

Roughly 30x50 inches in area and weighs around 30 lbs.

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Modules

A group of modules is called an array.

Generate electricity from sunlight, 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

Most residences have from 15 to 40 panels.

Will generate anywhere from 2,000 to 5,000 watts (two to five kilowatts) in optimal sunlight conditions, at between 120 and 600 volts DC.

Current ranges between five and nine amps.

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Inverters and Disconnects

Modules wired to an inverter, which converts the DC voltage to AC and then feed the electricity back into the main power distribution panel. The inverter requires AC from the power company, shutting off the main breakers also shuts down the inverter. Disconnects are often mounted on one or both sides of 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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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.

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!!!!!!

Photovoltaic Array

Photovoltaic Array

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Tripping and/or falling hazards while operating on the roof.

Earlier roof collapse due to extra weight. Hot water scalds with the Thermal system. Electric shock. Battery hazards. Inhalation exposure. Access for ventilation.

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Potential Hazards from Solar Systems

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Inform the IC that a system is present.

Size-up, identify and validate hazard;• locate rooftop panels• obtain system information• type of system (Thermal or Photovoltaic)• clarify electrical disconnects

Stress tactical approach, STAY CLEAR• shut down as much as possible, “Lock-out”- “Tag-Out”

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Fireground Tactics

Leave the scene in a safe condition, i.e., system damaged during night fire, when exposed to sunlight begins to generate electric.

At night, apparatus scene lighting does not produce enough light to generate an electrical hazard.

Light from a full moon will not energize the PV cells.

Lightning is bright enough to create a temporary surge.

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Fireground Tactics

Covering the PV modules with normal FD tarps WILL NOT block light generation. Only 100% opaque materials will work.

Foam cannot effectively block all sunlight.

If your department carries “noncontact voltage detectors”, they only detect AC voltage, not DC voltage.

Daytime = Danger; Nighttime = No Hazard Components are always HOT! (Daytime = sunlight,

Nighttime = batteries.)

Operate normally, but don’t touch. Treat as electrically energized.

Securing the MAIN electrical does not shut down the PV modules.

Do not break, remove, or walk on PV modules and stay away from modules, components and conduit.

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Summation