SMA Solar Technology AG
Installation Guide
SB50US-80US-IUS094030
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1.3 Safety
Anti-Islanding Protection
Islanding is a condition that can occur if the utility grid is disconnected while the Sunny Boy is
operating and the remaining load is resonant at 60 Hz and matches the output of the Sunny Boy
perfectly. This condition is highly unlikely and had never been witnessed outside of a controlled
laboratory. Nevertheless, the Sunny Boy incorporates an advanced active islanding protection
algorithm to ensure that the system will not export power into a balanced 60 Hz resonant load while
the utility is disconnected. The Sunny Boy periodically injects both leading and lagging reactive
current into the utility grid. This method has been proven by Underwriters Laboratories to effectively
destabilize and disconnect from a balanced island condition.
PV Ground Fault Detection and Interruption
The Sunny Boy is equipped with a ground fault detection device. If a ground fault current greater than
1 Amp is detected, the Sunny Boy will shut down and display the fault condition on the user interface
display. Once the ground fault is located and corrected, the ground fault error will need to be
manually cleared and the inverter will then resume normal operation.
PV Series Fusing
Series fusing may be required depending on the type of PV module used in the system. See NEC
690.9
Interconnection Code Compliance
The Sunny Boy has been tested and listed by Underwriters Laboratories to meet the requirements of
UL1741 Static Inverters and Charge Controllers for use in Photovoltaic Power Systems and UL1998
Software in Programmable Components, as well as IEEE-929-2000 Recommended Practice for Utility
Interface of Photovoltaic Systems and IEEE 1547 Standard for Interconnecting Distributed Resources
with Electric Power Systems. The Sunny Boy is also listed under UL1741 for Canadian UL.
FCC Compliance
The Sunny Boy has been tested and shown to conform with all FCC Part 15 A & B EMI/EMC
emissions regulations.
Contact the local utility and/or the authority having jurisdiction prior to connecting the
Sunny Boy to the utility grid.
