SMA SB 2800i - Manual (Page 14)

Device Description Operating Instructions
12 SMA Regelsysteme GmbH SB2800i-11:FE0504
3.3.2 Critical Failure States
Due to a comprehensive safety concept, the number of critical
operating states could be reduced to one:
Input voltage exceeding specification
This is shown with the following blinking code of the yellow LED:
When failure occurs, the yellow failure LED is on for five seconds
and then starts to send the blinking code by remaining off for
three seconds and blinking four times in short intervals. The code
is sent three times. If the failure persists the code is repeated.
Immediately disconnect the PV generator from the inverter! The
Sunny Boy can otherwise be severly damaged.