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Does solar panel current affects inverter output current?

cizera

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Aug 19, 2021
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-My 18 x 330w Canadian solar produces 8.8A
-VFD Inverter maximum - 17A
-3 phase 4kw pump requires 9.8A
Are the panels going to drive the pump with their output current of 8.8 A
 
Current is largely irrelevant when you are changing voltage like that. Wattage can be converted as needed to different voltage which will then dictate your availability of current.



Based on your numbers you have 5940 watts of solar. Assuming you get 80% of the rated output you'll have 4752w to run with.

However, your inverter will have efficiency losses. If it's the "typical" 85% then a 4000w pump will need 4705w from the panels/battery.

What you need to do at this point is know how long the pump needs to run, whether it has startup surge or if that vfd inverter can do a soft start, and whether you'll have battery storage.


Also, is this system installed ready or are you still planning?
 
Still pla
Current is largely irrelevant when you are changing voltage like that. Wattage can be converted as needed to different voltage which will then dictate your availability of current.



Based on your numbers you have 5940 watts of solar. Assuming you get 80% of the rated output you'll have 4752w to run with.

However, your inverter will have efficiency losses. If it's the "typical" 85% then a 4000w pump will need 4705w from the panels/battery.

What you need to do at this point is know how long the pump needs to run, whether it has startup surge or if that vfd inverter can do a soft start, and whether you'll have battery storage.


Also, is this system installed ready or are you still planning?
Still planning but
VFD Inverter ,pump ,and 14 solar panels are available
 
You may wish to post a list of what components you'll be using for folks to give you a better idea.

I'm guessing so far that what your original post states will be insufficient, but that depends on a lot of things.

Powering something isn't a matter of just applying voltage and meeting the current needs. It depends on run time and frequency of stop/starts.
 
You may wish to post a list of what components you'll be using for folks to give you a better idea.

I'm guessing so far that what your original post states will be insufficient, but that depends on a lot of things.

Powering something isn't a matter of just applying voltage and meeting the current needs. It depends on run time and frequency of stop/starts.
Ok it's for water pumping
130 m from a borehole and 200 m lateral to the reservoir .I want to use a 3 phase 4 kW AC PUMP using solar panels and VFD pump drive .

#PUMP Parameters 400v ,9.8 A. 4 KW
#Parameters for Solar Variable Frequency Drive
- 0.75 - 7.5 kW
- 380 - 450 v AC output
DC input 750 , maximum 800v
INPUT CURRENT 20.5A
OUTPUT CURRENT 17A

#SOLAR PANEL parameters -
14 x 330w
Voc 45v
Operating 37.5
 
14 panels is insufficient for full pump power. You will almost never see rated wattage out of them and the inverter losses push the full load demand above what you'll have.

However. It may be able to run if you can cut the power requirements back by slowing down the pump with the VFD. That would be a question for someone wiser than me. My experience with VFDs has never been for the purpose of power saving.

Looks like the vfd is designed for pumps and should provide soft start?
 
14 panels is insufficient for full pump power. You will almost never see rated wattage out of them and the inverter losses push the full load demand above what you'll have.

However. It may be able to run if you can cut the power requirements back by slowing down the pump with the VFD. That would be a question for someone wiser than me. My experience with VFDs has never been for the purpose of power saving.

Looks like the vfd is designed for pumps and should provide soft start?
yes more panels are coming to make them 18
 
No batteries?

What’s the VFD make and model? I imagine you’d run each panel in series to try and get 700VDC? Be careful of string voltages this high, much different insulation class in this range.
 
According to your drive specs
1643315616887.png
max input voltage is 800. 18 panels in series with Voc 45v will give 18x45= 810v - a little bit over the limit.
18 panels in 2S2P with Vmp=37.5 will give operating voltage 37.5x9=338v and Vmax=405V - which is good for the drive.
In this configuration, assuming panels do produce 8.8 amps, you will have 17.6 amps at 338v, almost 6kW - enough to run the pump.
In reality, even on a good day, output will be about 75% of rated power or about 4.5kw - still enough to run the pump.
And according to the manual, the VFD starts at 35Hz (about 50% speed) to check sun conditions. Reducing speed 2 times reduces required pump power 4 times if this is a centrifugal pump. For that there will plenty of power even in a cloudy day to start the pump . Your pump will start slow and then VFD will bump the speed up to available sun power ( or so they say in the manual).
 
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