SMA America announced its Sunny Boy-US series is the first residential inverter to achieve Underwriters’ Laboratories (UL) 1741 SA (Supplement A) listing, which has been mandated by California and Hawaii for compliance in September 2017. Most if not all states are expected to follow suit, adopting these so-called smart-grid requirements for inverters.
Under the new rule, UL specifies test methods for grid support that allow distributed-generation (DG) devices to remain online and adapt to grid instability by adapting their output and overall behavior to stabilize the grid during abnormal operation rather than simply disconnecting.
California has announced that inverters installed in the state will be required to comply with the Rule 21 grid-interconnection requirements within one year of publication of the UL 1741 SA. Other states are actively considering adopting similar installation requirements, especially in areas with high levels of DG and solar penetration. Rule 21 is the inverter-related revision to the California Electric Tariff Rule 21 made by the California Public Utility Commission (CPUC).
Rule 21 is a Source Requirement Document (SRD) to be used with the UL 1741 SA. SRDs set specific parameter settings to be used with the test methods of the UL 1741 SA. Other SRDs may also be used with the UL 1741 SA as other markets look to build smart-grid functionality into the modernization of their electrical power system, UL notes.
“We are pleased to see SMA making a continued, concerted effort to manufacture inverters that will help meet the needs of the modern utility grid,” said Jeff Smidt, vice president and general manager, UL Energy and Power Technologies division. “The certified models of the Sunny Boy-US line of residential inverters meet the safety requirements and comply with the specifications of UL 1741 SA.”