Operating State Derating
(en) The “Derating” operating state indicates the controlled reduction of the power and is a normal operating state that may occur occasionally and can have several causes.
Derating has no negative effects on the inverter. At first, Derating is indicated as an operating state by the status indicator LEDs and the inverter display. If the inverter remains in this state for more than a few minutes, it issues a “Derating” warning. The inverter continues to display this warning until it shuts down at sunset.
Derating caused by Temperature
Temperature derating occurs when the inverter reduces its power in order to protect internal components from overheating. Once the permissible temperature on the monitored components is reached, the device shifts its operating point to a reduced power level. The power is reduced in steps. In extreme cases, the inverter will shut down completely. As soon as the temperature of the sensitive components falls below the critical value again, the inverter returns to the optimum operating point.
Temperature derating can occur for many reasons, e.g. if the inverter cannot dissipate heat due to unfavorable installation conditions. If the Sunny Boy / Sunny Mini Central frequently switches to this operating state, check the heat dissipation, as described in the device’s installation or user manual. If the inverter has fans (e.g. all Sunny Mini Central and Sunny Boy SB 3300/3800 models), also check whether the fans are functional and not contaminated. This check is described in the device’s installation or user manual.
The installation and user manuals are available to download in the Archive of the Download area at https://www.sma.de/en/service/downloads.html.
Display message “Derating” caused by the commands of an external source of system control
In Sunny Boy and Sunny Mini Central devices with older firmware versions (approx.. before 2010) , the message “Derating” can be caused by commands from an external source of system control (Power Reducer Box or third-party products, such as Solarlog).
Background information: When using an external source of system control, the inverter reduces its active power in accordance with the specifications of the grid operator. For the control commands to be implemented, a compatible firmware status is required in the inverter. In some older firmware versions (rule of thumb: firmware versions before 2010, see compatibility list for detailed breakdown), although the control commands can be implemented to some extent, the green LED flashes continuously and the “Derating” display message is also continuously displayed if the inverter does not reduce its power.
This purely display-related problem can be resolved if desired by installing an up-to-date firmware chip. In the compatibility list “PRB_Komp-PL-de,” which can be downloaded at https://www.sma.de/en/service/downloads.html , the compatible firmware versions are listed in detail. If required, the firmware chips can be ordered for a fee from SMA Service.
Electric current derating, derating ldc
Depending on the module type or the PV array power and circuitry, the PV-side input current exceeds the maximum possible input current. The inverter switches to the electric current derating operating state to protect itself from an overload. If this display appears regularly, the system design and module circuitry should be checked by an installer.
All work on the inverter and the cabling of the PV array must be carried out by an electrically qualified person. SMA accepts no liability for the information and solutions given in the Online Service Center. Additional information can be found in our Online Service Center’s terms and conditions of use.