Inverter output power and the loads

SYKSolar

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Can someone explain this:
I watched Will Prowse's video and elsewhere that they cut a 12awg extension cable to connect to the inverter output terminals. We can buy a 12 awg extension cord with 1-3 outlets. I asked Signature Solar what was the AC output and the answer was 120V 20A. That would mean a maximum power of 2400W only and that would mean the max power the load/loads can draw simultaneously, correct?.
I just pre-order the SPF 3K LVM-ES Growatt inverter. I don't see the specs said about the voltage or correct stted individually. My questions are:
Q1: Even you have a 5K inverter, how would you get a 3K or 5K power from the inverter assuming you have enough solar panels to generate that power if output voltage is about 120V? The amps would have to be greater.
Q.2: Assuming you get an output power of 3K of power, I would think the voltage would vary and not 120V maximum where as the amperage would be around 20 amps,. Otherwise, the output wire from the inverter has to be a smaller awg r(bigger wire) to satisfy the rating.
Please comment and educate me.
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Thanks
 
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Supervstech

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Can someone explain this:
I watched Will Prowse's video and elsewhere that they cut a 12awg extension cable to connect to the inverter output terminals. We can buy a 12 awg extension cord with 1-3 outlets. I asked Signature Solar what was the AC output and the answer was 120V 20A. That would mean a maximum power of 2400W only and that would mean the max power the load/loads can draw simultaneously, correct?.
I just pre-order the SPF 3K LVM-ES Growatt inverter. I don't see the specs said about the voltage or correct stted individually. My questions are:
Q1: Even you have a 5K inverter, how would you get a 3K or 5K power from the inverter assuming you have enough solar panels to generate that power if output voltage is about 120V? The amps would have to be greater.
Q.2: Assuming you get an output power of 3K of power, I would think the voltage would vary and not 120V maximum where as the amperage would be around 20 amps,. Otherwise, the output wire from the inverter has to be a smaller awg r(bigger wire) to satisfy the rating.
Please comment and educate me.
Thanks
The wattage divided by the voltage gives the amperage.
So, the 5000W inverter has around d 42A...
So that would need a #6 copper wire feeding a distribution panel.

The 3000VA actually 2400W at 120V will output around 20A max...
 

SYKSolar

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The wattage divided by the voltage gives the amperage.
So, the 5000W inverter has around d 42A...
So that would need a #6 copper wire feeding a distribution panel.

The 3000VA actually 2400W at 120V will output around 20A max...
I know W =IV.
I don't think you answered what I asked.
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Can someone answer whether the voltage or amperage output vary and how much each varies. Thanks
 
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WYtreasure

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As long as an inverter receives enough power, the output power should remain within the tolerances specified by the manufacturer.

Volts and Amps should be relatively constant coming from the inverter.
 

SYKSolar

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Ok, I guess I don't understand.

Voltage shouldn't vary unless amperage is exceeded...
I believe in my case that I have a 3000W inverter, the output voltage is 120V , the amperage would be about 25 amps max ( 25 x 120 = 3000K). Then a 10 awg copper wire to the load center is more than enough. Agree?
 

WYtreasure

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I agree, as long as the 10 awg is rated for more than your inverter can produce in Amps.
Are you considering your inverter "surge" rating?

I have a 3000W inverter and am using 8 awg rated @ 55 Amps, to my AC panel just to be on the safe side.
 

SYKSolar

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I agree, as long as the 10 awg is rated for more than your inverter can produce in Amps.
Are you considering your inverter "surge" rating?

I have a 3000W inverter and am using 8 awg rated @ 55 Amps, to my AC panel just to be on the safe side.
Make sense to consider. I follow your lead. Thanks for the suggestion. And the inverter specs said:
1652297312009.png
And I don't agree with Will Prowse using a 12 awg extension cable to connect to the output terminals.
Signature Solar just told me he gave the wrong amps for the 3K inverter. It is 25 amps not 20 amps!
 
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Supervstech

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Keep in mind it isn't a 3000W inverter...
It is a 3000VA inverter.
So most continously output is going to be around 2400W which is 20A.
Check the rating plate to confirm.
 

SYKSolar

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Keep in mind it isn't a 3000W inverter...
It is a 3000VA inverter.
So most continously output is going to be around 2400W which is 20A.
Check the rating plate to confirm.
Man, You confused me. Isn't 3000VA=3000W. Look at the specs I posted earlier. It said 3000VA/3000W Inverter!
 

Supervstech

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Man, You confused me. Isn't 3000VA=3000W. Look at the specs I posted earlier. It said 3000VA/3000W Inverter!
That’s cool.
VA usually equals watts, but not with AC… power factor and real power, etc offset the output unless it is a pure resistive load. Motors/inductors have a power factor that eats into the output.
 

timselectric

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My inverter can share the loads with the grid. So my AC out wiring is sized for the total output of both. While my AC input wiring is sized for the grid pass through amount.
 

WYtreasure

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In this case it probably will be fine. Since the surge is only for about a second. Then the inverter starts screaming "Danger Will Robinson, Danger ". lol
There ya go @SYKSolar, someone who really does know has answered your question and received a thumbs up from another someone who knows. Listen for the robot 🤖 or smoke alarm. ;)
 

SYKSolar

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Thanks all for the comments and discussion.
I am not using a cut extension cable anyway. The inverter suggests 8 AWG.
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I go with it.
 

SparkyJJO

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Keep in mind it isn't a 3000W inverter...
It is a 3000VA inverter.
So most continously output is going to be around 2400W which is 20A.
Check the rating plate to confirm.
No, it will be 25A. 3000VA / 120V = 25A.

Lagging waveforms from out of sync amperage vs voltage is what gives you a lower overall power output. But you can still have the higher amperage if that's the case.

Example - two computer power supplies are identical except one has active PFC and the other does not. Both provide 500W of power, at 80% efficiency, so 625W from the wall at that output level. The PFC unit pulls 5 amps. However, the non-PFC unit is pulling closer to 8 amps due to a poor power factor of 0.65.
 

740GLE

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Correct poor PF reduces watts capacity of the inverter, but the VAR demand still needs to be supplied by the conductor, and conductors are limited by current/heat.
Best case scenario the inverter can supply 3000w of resistive load so continually, IMO size the conductor for surge rating such that voltage drop will be negligible.

The run from the inverter to a distribution panel should be pretty short so even if it’s #6 it shouldn’t be that expensive.
 
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Supervstech

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No, it will be 25A. 3000VA / 120V = 25A.

Lagging waveforms from out of sync amperage vs voltage is what gives you a lower overall power output. But you can still have the higher amperage if that's the case.

Example - two computer power supplies are identical except one has active PFC and the other does not. Both provide 500W of power, at 80% efficiency, so 625W from the wall at that output level. The PFC unit pulls 5 amps. However, the non-PFC unit is pulling closer to 8 amps due to a poor power factor of 0.65.
You are absolutely correct, I don't know what I was thinking...
 

SYKSolar

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Correct poor PF reduces watts capacity of the inverter, but the VAR demand still needs to be supplied by the conductor, and conductors are limited by current/heat.
Best case scenario the inverter can supply 3000w of resistive load so continually, IMO size the conductor for surge rating such that voltage drop will be negligible.

The run from the inverter to a distribution panel should be pretty short so even if it’s #6 it shouldn’t be that expensive.
You are right, the distribution panel should be located just next to the inverter. Two feet of #6 should be long enough.
 
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