SMA STP 33-US-41 - Setting SMA Shadefix; Generating the I-V Characteristic Curve

4 Operation
SMA Solar Technology AG
User Manual STP33-62-US-41-BA-en-11 39
4.17 Setting SMA ShadeFix
You can set the time interval in which the inverter has to determine the optimum operating point. If
you do not want to use SMA ShadeFix, you can disable the feature.
The basic procedure for changing operating parameters is explained in another section (see
Section4.11 "Changing Operating Parameters", page34).
Procedure:
• In the parameter group DC-side > DC settings > SMA ShadeFix, set the parameter Time
interval of SMA ShadeFix and set the required time interval. The ideal time interval is
usually six minutes. This value should only be increased if the shading situation changes
extremely slowly.
☑ The inverter optimizes the MPP of the PV system at the predetermined time interval.
• In order to disable the SMAShadeFix feature, in the parameter group DC-side > DC settings
> SMA ShadeFix, set the parameter SMA ShadeFix switched on to Off.
4.18 Generating the I-V Characteristic Curve
During the measurement, the inverter can briefly interrupt the feed-in or feed in with reduced power.
The duration of a measurement is approx. 20 seconds per MPP tracker. To avoid misuse of the
function and thus yield loss, the measurement can be carried out a maximum of 10 times per day. If
more than 10 measurements per day are to be carried out, the inverter must be restarted.
The measuring curve has over 200 measuring points. The display is from 0V up to the maximum
MPP voltage of the inverter. The current is limited by the maximum possible input current of the
inverter.
The data is stored on the user interface until the next measurement.
Further information as well as help for the interpretation of the I-V-characteristic curve can be found
in the technical information "I-V diagnostic function: Determination of the generator characteristic
curve by the inverter for fault detection in the PV array".
Using the function when using external module optimizers is not
recommended.
Using the function when using external module optimizers does not produce interpretable
results and is therefore not recommended.
Requirements:
☐ In order to avoid misinterpretation of the determined characteristic curve at low powers, a
measurement should be carried out at at least 50% of the inverter's nominal power.
☐ In the case of comparative measurements (e.g. at annual intervals), similar ambient conditions
(solar irradiation, shading, temperature) should prevail.
Procedure:
1. Log on to the user interface of the inverter.