Code compliance with Fronius

Our solutions for compliance

We are committed to make sure that all our solutions are fully compliant with the latest codes and standards. Furthermore, our engineers are pro-actively involved in industry standardization groups.

NEC 2014 – Rapid Shutdown

All Fronius SnapINverters are compliant with the NEC 2014 (690.12) and NEC 2017 (Array Disconnect) compliance code requirements. We are proud to offer a bankable solution to the latest National Electrical Code (NEC) requirements of Rapid Shutdown function (NEC 690.12) on rooftop photovoltaic systems. The Fronius Rapid Shutdown Box ensures NEC 2014 (690.12) compliance code compliance while enhancing rooftop and firefighter safety, quality, reliability and the most seamless solution available on the market.

NEC 2017 – Module Level Shutdown


To offer solar installers an easy plug-and-play solution for the NEC 2017 module level shutdown requirement, Fronius believes that the best solutions are based on an industry standard with Power Line Communication (PLC). The SunSpec Communication Signal for Rapid Shutdown provides this standard. This industry standard is a multi-vendor and multi-device communication specification for inverters, modules, and string combiners to support NEC 2014, NEC 2017, and UL 1741 module-level rapid shutdown requirements. 

For more information about the SunSpec Alliance visit their website: 

Fronius Symo Advanced

The Fronius Symo Advanced comes with an integrated Power Line Communication (PLC) transmitter based on the SunSpec Rapid Shutdown communication standard. Solar installers get a simple and cost-effective solution for module level shutdown.   

Rule 21

“Rule 21” refers to the generator interconnection requirements of each CA Investor-Owned Utility (IOU). A years-long process has been underway to update Rule 21 with “smart inverter” requirements in a phased approach. Rule 21 Phase 1 contains the most important autonomous functions that can be set at installation time, and whose settings wouldn’t necessarily change over time. Phase 2 addresses communications requirements. Phase 3 development is ongoing and would address further autonomous functions and communications-based functions. This document only covers Phase 1 in which the timeline and most details have already been defined. Ongoing discussions with the CA IOUs and other stakeholders are addressing remaining Phase 1 implementation issues.

Rule 21 requires inverters to have new functions and a new certification under UL 1741. Inverters receive a new nameplate label that identifies it as a “Grid Support Utility Interactive Inverter.” Besides new firmware, certification and the label, all else remains the same. The following grid support functions are required:

  • / Voltage and frequency ride-through
  • / Set Power Factor
  • / Volt-var
  • / Soft start ramp rate
  • / Normal ramp rate

For more information about Rule 21 visit