PV inverter overfrequency derating standard

Does temperature derating affect a PV inverter?

In this case, the maximum DC voltage of the inverter acts more as a technical boundary than a normal operating curve. There is no PV array operating point that requires the inverter to feed in at full power at temperatures above 31°C (at 800 V). On principle, temperature derating has no negative effects on the inverter.

What is derating a solar inverter?

Derating is the controlled reduction of the inverter power. In normal operation, inverters operate at their maximum power point. At this operating point, the ratio between PV voltage and PV current results in the maximum power. The maximum power point changes constantly depending on solar irradiation levels and PV module temperature.

What is a temperature derating inverter?

Temperature derating prevents the sensitive semiconductors in the inverter from overheating. Once the permissible temperature on the monitored components is reached, the inverter shifts its operating point to a reduced power level. The power is reduced in steps. In extreme cases, the inverter will shut down completely.

How to avoid derating at peak PV array outputs?

In order to avoid derating at peak PV array outputs, an inverter with a nominal power of more than 100% of the PV array power could be selected. However, this would shift a larger proportion of partial load yields to a range within which the inverter is relatively inefficient.

What is a derating behavior of an inverter?

This behavior reduces the inverter output power (derating). In this document, the derating behavior of the inverters is shown in graphic form. The derating behavior is given for the minimum MPP voltage, the rated input voltage and the maximum MPP voltage.

How to test a PV inverter?

For “Frequency Shift Test”, this is designed for customers to test PV inverter if it has the overfrequency derating function, which is not necessary for customer to set. Customers can set any frequency value more than 50Hz for test. For example, input 51Hz in “Set Test Frequency” then check the PV inverter AC output power.