Generating the I-V Characteristic Curve

Only the STP 50-41 is equipped with this function.

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: