Background:
1. The customer purchased a SUN2000-20KTL-M0 for testing in a lab environment. The input voltage was 530 V DC. The customer reported that the current dropped intermittently after the inverter was connected to the grid.
Problem analysis:
1. Analyzed the 5-minute SUN2000 logs and found that the PV current frequently dropped and rose.
2. Generally, the input source of a PV inverter is a PV module or PV simulator with module characteristics. The inverter can work properly only after the maximum power point is determined based on the input source characteristics (MPPT tracing algorithm).
When the input source is a constant voltage source, the MPPT tracking algorithm cannot determine the maximum power point of the input source. As a result, the SUN2000 cannot work properly.
Suggested measures:
3. The onsite input power source does not support PV module features. You are advised to purchase a DC power source with the PV simulator function for testing.
