Cause of occurrence：

(1) The output voltage of the module or string is lower than the minimum working voltage of the inverter.

(2) The input polarity of the string is reversed. The DC input switch is not closed.

(3) The DC input switch is not closed.

(4) One of the connectors in the string is not connected properly.

(5) A component is short-circuited, causing the other strings to fail to work properly.

Solution:

Measure the DC input voltage of the inverter with the DC voltage of the multimeter, when the voltage is normal, the total voltage is the sum of component voltage in each string. If there is no voltage, test whether the DC circuit breaker, terminal block, cable connector, component junction box, etc. are normal in turn. If there are multiple strings, disconnect them separately for individual access testing. If there is no failure of external components or lines, it means that the internal hardware circuit of the inverter is faulty, and you can contact Renac for maintenance.

Cause of occurrence:

Mainly because the grid impedance is too large, when the PV user side of the power consumption is too small, the transmission out of the impedance is too high, resulting in the inverter AC side of the output voltage being too high!

Solution:

(1) Increase the wire diameter of the output cable, the thicker the cable, the lower the impedance. The thicker the cable, the lower the impedance.

(2) The inverter is as close as possible to the grid-connected point, the shorter the cable, the lower the impedance. For example, take 5kw grid-connected inverter as an example, the length of the AC output cable within 50m, you can choose the cross-sectional area of 2.5mm2 cable: the length of 50 – 100m, you need to choose the cross-sectional area of 4mm2 cable: length greater than 100m, you need to choose the cross-sectional area of 6mm2 cable.

Cause of occurrence:

Too many modules are connected in series, causing the input voltage on the DC side to exceed the maximum working voltage of the inverter.

Solution:

According to the temperature characteristics of PV modules, the lower the ambient temperature, the higher the output voltage. It is recommended to configurate the string voltage range according to the inverter datasheet. In this voltage range, the inverter efficiency is higher, and the inverter can still maintain the start-up power generation state when the irradiance is low in the morning and evening, and it will not cause the DC voltage to exceed the upper limit of the inverter voltage, which will lead to the alarm and shutdown.