PV Solar Panel

I install 26 PV Solar Panel of 255 Watt, VOC 34 Volt, SC Current 7.3 Amp, Application Water Pump, 3phase Motor with inverter, 13 Panel use in series (02 Strings use in Parallel).

Voltage at inverter terminal are 414 VDC. When run 3 Phase motor, unloaded motor run normal till 50 Hz. When put pump load after achieving 35 Hz, load increased, and DC input voltage of inverter decreased speedily toward 300 VDC. Inverter tripped at protection under volt.

Please suggest me its problem of PV panels or Pump? All PV Panels SC current normal 7.3 Amp and VOC 34 VDC.
All such installations require suitable batteries that the PV panel maintains the charge between uses...
You left out the most important information:

1- what is the HP of the motor
2- what is the kVA rating of the inverter

A motor when starting will draw 10X it's rated current for a few cycles.

You need an inverter rated for that and a battery bank to provide that short duration peak surge.

good luck