The next generation in smart module technology
Understanding NEC 690.12
Rapid Shutdown Of PV Systems
And Trina’s New Robust Rapid Shutdown Solution,
Trinaswitch
PV Safety
Written with contributor:
Matthew Paiss, Fire Captain and
Owner Of Energy Response Solutions
Fire Captain Matthew Paiss is a 19 year
veteran of a metropolitan fire department in California, and owner of Energy
Response Solutions, specializing in PV
(photovoltaic) safety education and
consulting. He is currently a member of
the International Association of Fire
Fighters (IAFF) and primary representative
to the NEC (P-04) of California. Paiss has
delivered PV safety training to over 6,000
firefighters across North America and
contributed to both national model Fire
Code sections on PV. He has spoken in
Europe on fire safety and PV design, and
has AS degrees in both Solar Energy
Technology and Fire Science. He is a
member of UL Standards Technical
Panels 1703 & 1741 and has written for
Fire Engineering, SolarPro, and Home
Power magazines.
About Trina Solar Limited
Trina Solar Limited (NYSE:TSL) is a global
leader in photovoltaic modules, solutions
and services. Founded in 1997 as a PV
system integrator, Trina Solar today drives
smart energy together with installers,
distributors, utilities and developers
worldwide. The company's industry-shaping position is based on innovation
excellence, superior product quality,
vertically integrated capabilities and
environmental stewardship.
For more information, please visit
www.trinasolar.com. - See more at:
http://www.trinasolar.com/us/product/Trinasmart.html
Trina Solar Limited
www.trinasolar.com
Background On The Fire Codes Impacting
PV Solar Installations
PV solar systems’ design and installation today are regulated by various
residential and commercial codes. How these standards or codes
are developed is important in understanding the current code and
future revisions.
International Building Codes (IBC or I-Codes) are published by the
International Code Council (ICC) which collaborates to develop
standards that guide construction for building safety and fire prevention.
Fifty states and the District of Columbia have adopted the I-Codes.
The ICC also publishes the International Residential Code (IRC), the
International Existing Building Code (IEBC) and the International Fire
Code (IFC). The IFC code is adopted statewide in approximately 31
states.
The National Fire Protection Association (NFPA) is a international
non-profit organization established to reduce the burden of fire and
other hazards. They develop, publish and disseminate more than 300
consensus codes and standards. Of those codes, NFPA1 or the Fire Code
(adopted statewide in 19 states) and NFPA 70 (adopted in all 50 states)
or the National Electrical Code (NEC) are the guiding standards.
Fire Codes: NFPA1 & IFC
The two “Model Fire Codes” utilized in the US, the NFPA1 and IFC,
address minimum requirements for building construction, operation
and maintenance, fire department access, and hazardous materials
necessary to establish a reasonable level of fire safety and property
protection in new and existing buildings. Each code is updated every
3 years and is on the same cycle with 2014 being the latest cyclic
revision. Both codes are written through a consensus process with
technical panel members and represent numerous stakeholders.
About National Electrical Code (NEC)
The NEC, a regionally adoptable standard for the safe installation of
electrical wiring and equipment in the US, is updated on a 3 year cycle.
The NEC is adopted at varying years by each state with the exception
of AZ, MS, and MO. The challenge is, at any given time, states are
following 3 different code versions which span 9 years of improvements.
This is a challenging environment to effectively implement positive
change and safe electrical codes.
The Technical Committees responsible for updating the code are divided
into 19 code making panels (CMPs) to handle the work of the 9 chapters
vand subsequent articles. These CMPs are made up of various stakeholders including NRTLS, IEEE, Firefighters, Task Groups, authorities having
jurisdiction (AHJ) organizations, manufacturers and system providers.
The next generation in smart module technology
Code Reference: 690.12
Rapid Shutdown Of
PV Systems On Buildings
PV system circuits installed on or
in buildings shall include a rapid
shutdown function that controls
specific conductors in accordance
with 690.12 (1–5) as follows:
1.) Requirements for controlled conductors shall apply only to PV system
conductors of more than 1.5 m (5 ft.) in
length inside a building, or more than
3 m (10 ft.) from a PV array.
2.) Controlled conductors shall be
limited to not more than 30 volts and
240 volt-amperes within 10 seconds
of rapid shutdown initiation.
3.) Voltage and power shall be measured
between any two conductors and
between any conductor and ground.
4.) The rapid shutdown initiation methods
shall be labeled in accordance with
690.56(C).
5.) Equipment that performs the rapid
shutdown shall be listed and identified.
Understanding NEC 690.12
Rapid Shutdown Of PV Systems
And Trina’s New Robust Rapid Shutdown Solution,
Trinaswitch
2014 NEC 690.12: Rapid Shutdown Provision - The Intent
Introduced in the NEC 2014 and considered to be one of the most
important additions, Section 690.12 “Rapid Shutdown of PV Systems
on Buildings” was intended to provide for the ability to shut down a
rooftop mounted PV system to a lower voltage level (also extends to
ground-mount systems if conductors are on or entering a building
for more than 5 feet). This allows emergency responders to perform
emergency operations with limited risk of shock should contact with
damaged components occur. When this section was initially proposed,
the code required shutdown at the module level. Through the comment
and revision phase, it was modified to array-level as a result of concerns
over reliability and available compliant products. Manufacturers andthe
solar install community needed more time to respond to the changes.
The fire service agreed to an incremental approach and stated that a
further reduction of voltage would be proposed in the next cycle (2017).
Intent of Rapid Shutdown:
-Reduce the area of energized conductors in an emergency
-Be automatic upon activation of manual disconnect or loss of grid
-Reduce voltage in the entire DC run from array to boundary to invert
to <30V
The rapid shutdown as it currently stands is an array-level shutdown
and provides a zone outside of the designated area where the shock
potential has been mitigated. This means that the module interconnects
and PV source-circuits located behind roof-mounted modules do not
have to be controlled by rapid shutdown. Nor do the DC conductors
running to and from a roof-mounted junction box or combiner box
(both PV source and output circuit conductors) as long as they are
within 10 feet of the array. Conductors that enter a junction box behind
a roof-mounted array and then proceed into the building need to be
controlled within 5 feet of entering the building. Conductors between
a battery bank and an inverter or charge controller could conceivably
be less than 5 feet long, and thus not subject to being controlled under
690.12. The code outlines equipment performing rapid shutdown
be listed. In order for a product to be listed, a standard safety test
procedure must be in place for certifying the product. The current
standard safety test procedure is UL 1741.
In reviewing the collaborative process implemented to evolve standards
and revise code, the sheer size of the stakeholder community and the
complexities of each of the many organizations, it becomes clear it is
an immense undertaking. Currently a solar system that is compliant with
NEC 2014 code can still leave an array at dangerous voltage levels
even after activation of the rapid shutdown initiator and, methods and
designs for achieving proper rapid shutdown are not clearly addressed
by code requirements. The well-intended modifications have led to a
lack of distinction between systems that have the ability to shutdown at
a module-level versus those that do not reduce the array’s voltage. The
title “Rapid Shutdown” is not quite actualized, however the community
is diligently working to resolve those gaps.
Trina Solar Limited
www.trinasolar.com
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The next generation in smart module technology
Upcoming NEC 2017 And
Proposed Changes to 690.12
Approximately 4,012 public inputs of
recommended changes have been
submitted to the NFPA for NEC 2017.
Here are topics that are being
discussed in respect to Section
690.12:
• Greatly increased detail of rapid
shutdown switch including location
and signs
• Revised array zone of within 1’
of modules
• Conductors voltage curtailed
to 80V within array zone
• Equipment required to be certified
for rapid shutdown
Passed First Revision Ballot:
• PV array voltage should be
reduced when main service is shut
down (should not require a unique
emergency activation device)
• Reduce conductor voltage within
PV array
< 80Vdc within array footprint
< 30Vdc outside of array
boundary (< 1ft)
• Requirement for all building
mounted systems (highest life
hazard and property values)
Understanding NEC 690.12
Rapid Shutdown Of PV Systems
And Trina’s New Robust Rapid Shutdown Solution,
Trinaswitch
Solar And Improving The Safety Of Emergency Responders
Fire Service Concerns & Real World Application
• Roof Access
• Unclear Shock Hazard
• Confusing Labels
There are 1.2 million fire fighters in the United States. 80 percent of
these personnel are volunteers. Training varies across the country,
with established NFPA standards as the goal, but the ability for all
departments to comply is very dependent on many factors. As a rule,
fire fighters have very basic electrical safety training (NFPA 70E is not
required). In real world conditions they may have to work in the vicinity
of a damaged solar system. In a fire, superheated smoke and gases
(which can exceed 1,200°F) rise to the ceiling and then bank down back
to the floor. One lungful of this smoke is deadly. Cutting a hole in the
highest point of the room allows the superheated gases and fire to rise
out of the building, rapidly improving visibility as well as the survivability
of the structure and those trapped inside. This offensive strategy called
“Vertical Ventilation” is a common tactic to support firefighters on the
hose line to advance inside to locate the seat of the fire and any victims.
Solar systems installed on the rooftop may be well-designed and
compliant with the current code and still be life threatening to
personnel fighting fires.
In the quest to save a property, firefighters may not be able to avoid
the solar array as outlined by the current code (conductors within 10’
from the array). Also there are other natural hazards besides fires that
can create dangerous situations for solar systems such as wind, hail, or
seismic events. It makes sense to utilize available technology to mitigate
these potential electrical hazards. Module level power electronics
(MLPE) can provide that level of safety. The development of rapid
shutdown is part of an ongoing collaboration between the firefighting
and solar install communities to continue to improve the safety of PV
systems as the solar market grows.
Module-level disconnect is top of mind in the National Fire Protection
Association, NEC standards body and the solar installation industry.
Stakeholder meetings are underway to reach agreement on these
disconnect requirements.
Solar installers have grappled with various technologies to comply
with rapid shutdown requirements. Many string inverters now have rapid
shutdown string combiners that can be cost effective but have limited
capabilities, compatibility and warranties and while they meet rapid
shutdown compliance, they deliver a lower level of safety. Microinverters
deliver module-level rapid shutdown safety, but come at a higher cost.
Smart module with power electronics can deliver module-level rapid
shutdown at cost-effective pricing and also provide solar installers more
capabilities, compatibility, and an industry-leading warranty.
Trina Solar Limited
www.trinasolar.com
3
The next generation in smart module technology
Understanding NEC 690.12
Rapid Shutdown Of PV Systems
And Trina’s New Robust Rapid Shutdown Solution,
Trinaswitch
Rapid Shutdown Compliant:
Trinaswitch
Introducing New
Trinaswitch, Robust Rapid Shutdown Solution
from Technology Leader, Trina Solar
Features:
• Onsite manual and automatic
module-level disconnect
Trina Solar, the world leader in module manufacturing and technological
innovation, has taken high tech to the next-level. Now you can choose
your smart modules’ capabilities. Meet Trinaswitch, where you can
opt in for the highest level of NEC Rapid Shutdown compliance and
safety for your solar systems. Embedded in the junction box, Trinaswitch
communicates with modules, the monitoring system and the designated
system manager(s) performing micro-level detection. The technology
can automatically or manually shut off electricity when a hazardous
threat is detected reducing every solar module output in the system
to zero watts and zero voltage, making system safety easy to install
and manage.
Module-Level Disconnect
• Cloud-based, module-level
monitoring, and reporting
on current, voltage, and power
• Compatible with any inverter
• Industry leading 25 year warranty
• Scalable to any size of residential
or commercial rooftop solar
system
• Easily upgrade residential and
commercial installations
(no re-wiring, no add-on boxes)
• Flexibility to add on Trinasmart
functionality (optimization, longer
strings and more)
You can now select how to best
equip your PV system by easily
adding Trinaswitch (module level
rapid shutdown and system monitoring), or power optimization for
increased performance and more.
Functionality in the new Trinasmart
system is now interchangeable,
cost-effective and your choice.
Chose the Industry Leader,
Trina Solar
In case of emergency, there is no climbing on the roof in search of the
shutdown switch. When first responders shut down the main AC breaker
of the facility, Trinaswitch is activated and rapidly reduces voltage in
the PV module leads to zero volts.
Embedded in the junction box of the module is the Trinaswitch
which measures module current, voltage, and power. The Trinaswitch
automatically activates when it detects a safety hazard for the module
or the entire system ensuring maximum protection for the solar array.
Whenever Trinaswitch’s rapid shutdown is activated, an alert is
generated. Programmable alerts can be sent to designated recipients
via email or text message. Alerts can also be sent to security systems
or building management systems via API.
Trinaswitch comes with a button called ‘PV-Safe’ prominently positioned
on the front panel of the Cloud Connect for easy manual access.
Pressing this button enables first responders, routine maintenance
workers, or system owners a fast and safe method to deactivate
voltage across the wires between modules and inverters’ (a.k.a
“homeruns”). Once the PV-Safe button is pressed, it sends a signal
to each module to deactivate and ensures firefighters, maintenance
personnel, and installers with absolute certainty that no high voltage
is present.
Trinaswitch is the most powerful cloud-based, asset management
and commissioning solution for your PV array. Install, configure, and
manage your system all from your mobile phone. This application not
only monitors your array, but enables you to interface directly with
Cloud Connect software via local WiFi. This enables installers to configure
systems, troubleshoot system issues on-site, set up the connection to
the internet, and much more. Trinaswitch system analytics track
production and proactively suggest maintenance actions to keep
systems operating at maximum efficiency.
Guaranteed with an industry-leading 25 year warranty, Trinaswitch does
not limit you to any specific inverter or string sizes. It’s functionality can
easily and cost-effectively be added to an existing system for NEC
compliance and PV safety.
Trina Solar Limited
www.trinasolar.com
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