VFD for Solar Pump system


World is growing and growing faster. Energy needs are growing alongwith. Fossil energy sources such as Coal, Oil, and Gas are going to exhaust soon. According to a serve Oil will last for next 80 years, Coal for next 150 years and gas for next hundred years. So now humans are finding new energy sources to survive. Solar energy is one of them. In near future you will find that most things will depend on solar energy. With the technology growing we now have solar AC drives. With this solar drives you can run most of the variable torque application such as Submersible water pump.

Application Overview

In this application solar energy generated through PV (Photo voltaic) Cells is given to Solar VFD.

The idea is to run the pump at the maximum possible frequency depending on the solar Cell output and sunlight . This means that when the sunlight  is maximum the speed of the motor (output frequency of VFD) must be the highest, but when the Sunlight decreases the speed of the pump should be decreased accordingly, and make sure that VFD does not shut off or go in low voltage fault due to less input voltage. This function is called as MPPT.



MPPT Means Maximum Power Point Tracking. 


So, how this Maximum Power point tracking is achieved. Here is the brief algorithm behind it.

DC Power generated through Solar cells is given to input of VFD. Through rectifier of VFD this DC supply goes to DC bus capacitors of VFD. Here VFD checks the DC bus voltage to Drive and accordingly adjust the output frequency of VFD. Once VFD is started it not stop until Input voltage goes too much low.

Now when sunlight increase Solar panel cell will give maximum output Voltage. At this time dc bus voltage of drive will increase accordingly and VFD will run motor at full speed(50Hz). But when sunlight decrease DC bus voltage will drop, so VFD will decrease the speed of Pump.






This solar inverter with MPPT  VF drive will give maximum torque even at minimum sunlight.

There is no need of any battery, directly connect the panel to the inverter and the output of the inverter can be connected to a three phase motor.

The DSP will track at which point the maximum power can be extracted from the

panel by varying the PWM and modulation frequency so the motor will run always extracting the maximum power from the panel and at a constant torque for the wide range of intensity of sunlight – morning till evening.




With the below  diagram you will understand the Basic Wiring diagram Of Solar VFD System.




With the application needs we can design wiring systems like Bypass systems for Generators or Mains 3 phase input. As per needs we should add Protections such as MCB, Contactors interlocks for bypass systems Etc.


Recommended Brands for Solar VFD system:


Delta, Hitachi, INVT and ABB




If you have any queries related to Solar Pump VFD systems you can email us call us. WE will be glad to help you. We can design system for you. also if needed we can arrange a trial at your site. So please feel free to write us @ info@solims.com



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