The National Electrical Code (section 690.12) sets the Rapid Shutdown (RSD) requirements criteria. This code changes from time to time, and compliance is required for all structure-mounted systems within the USA. Please remember to always review the latest changes to the Code before designing your next system.
Tigo is pleased to announce that the TS4-S, TS4-O, TS4-L, and junction box equivalent products (along with TS4-F and 2F PLC signaling controlled models) provide a solution to the NEC 690.12 requirements - assuming all the following requirements are met:
For NEC 2014 Compliance
- All modules are equipped with either one or a combination of the following TS4 units:
- TS4-S
- TS4-A-S (Safety models)
- TS4-O
- TS4-A-O (Optimizing models)
- TS4-L
- TS4-A-L (Optimizing with voltage limiting models)
or
- TS4-F
- TS4-A-F (Fire Safety models, only. Can not be combined with O, S, or L)
or
-
- All modules are Smart Modules (TS4-S/O/L) which are Integrated MLPE installed at PV module factory. They use the JES or HBF integrated junction box.
Along with:
- For O/L/S models: a Cloud Connect or Cloud Connect Advanced and 1 or more TAP(s) (or Gateways) or, for F models: a compatible RSS PLC signaling Transmitter, either Tigo Energy or inverter integrated.
- The Cloud Connect Advanced or the RSS Transmitter(s) are powered by the same AC Grid Power as the rapid-shutdown ready inverter
- (For non-RSS ready inverters, DC disconnect must also be switched off to enter Rapid Shutdown)
A Photovoltaic (PV) solar electric power system meeting the above criteria will initiate rapid shutdown compliant with NEC 2014 requirements when its main breaker is turned off. Once initiated, the outputs of all Tigo MLPEs will drop to 0 Amps and 0 Volts within 30 seconds. Once the array voltage is below 30V and 240V AC inside the PV Module Array boundaries, it meets the requirements of the NEC 2014 code.
These solutions were tested and certified by Intertek in October 2014.
For NEC 2017 Compliance
The required updates for NEC 2017 690.12, were mandated as of January 2019:
- All modules are equipped with either TS4-S/TS4-A-S or TS4-O/TS4-A-O with CCA and TAP, or TS4-F/TS4-A-F with RSS PLC signaling transmitter.
- The CCA/RSS Transmitter(s) are installed on the same power company AC service main circuit breaker as a rapid-shutdown ready inverter
- For non-RSS ready inverters, ensure that upon AC Grid Power loss, the inverter voltage drops below the required minimum between the (+) and (-) string wires and to Ground, within 30 seconds.
- For non-RSS ready inverters, ensure that upon AC Grid Power loss, the inverter voltage drops below the required minimum between the (+) and (-) string wires and to Ground, within 30 seconds.
- The inverter and Tigo TS4 products are tested and certified by UL on the following website: http://productspec.ul.com/document.php?id=QIJS.E469960.
When a PV system's AC solar disconnect is turned off, meeting the above criteria will initiate an RSD response that is compliant with NEC 2017 requirements (the outputs of all module leads to drop to 0 Amps and 0 Volts - within 30 seconds). The voltage drops below 80V (up to 1 ft or 305 mm from the array), while outside the array, the voltage drops below 30V, within 30 seconds, as defined by code.
For NEC 2020 Compliance
The NEC requirements (with a few exceptions) have largely remained unchanged since the last Code update (NEC 2017). There is no current mandate for NEC 2020, but you may review which states have adopted this code, here: IAEI - Code Adoption by State
- 690.12 (B)(2)(1) - A change to guidelines inside the array boundary: The NEC now requires a UL-listed or field-labeled “PV Hazard Control System” or PVHCS (as defined by UL 3741).
- 690.12 (C) - Initiation device rules changed from allowing up to six RSD switches, to a requirement of a single RSD per PV system. There can still be up to six rapid shutdown switches on a single service, but a PV system must have a single RSD switch or controlling device dedicated to it.
The informational note in 690.12(C)(3) has been updated to acknowledge that an RSD switch can serve standby systems as well as standalone systems (which may not have a PV AC disconnect to initiate RSD).
An informational note was removed from NEC 2017 that cautioned installers to be aware that non-rapid-shutdown-compliant inverters could have potentially energized DC input circuits for up to five minutes after AC disconnect (assuming that all inverters installed on permitted and inspected systems are UL 1741 compliant).
Lastly, the language of the code changed slightly. The term "Emergency Responders" has been specified to "Firefighters," and the circuits affected by code have been specified to DC conductors and the output circuits of the inverter that originate from inverters located within the array boundary (referring to microinverters and/or string inverters mounted in the center of, or immediately adjacent to, a rooftop array).
Source: Mayfield Energy
Please consult the Tigo Energy Installation and Safety Manual to ensure that the system is set up and configured properly. While doing this, you may also research our certified products.
Other available online resources:
- NFPA (National Fire Protection Association)
- ANSI (American National Standards Institute)
- UL (Underwriters Laboratories)
- IAEI (International Association of Electrical Inspectors)
For the full details of rapid shutdown and other safety functions with Tigo PV-Safe, click here.