EG4 6000EX running on rectified / converted DC input

[galstaf]

Hey all,
I am breaking off this discussion into a separate 6000EX thread as we kinda went down a rabbit hole with this topic. This thread is *specifically* for using the 6000EX with a rectified DC input on one of the solar input feeds.

Scenario: I have a boondock barn with 120VAC from a small 120V Honda Generator. I want to install a EG4 6000EX to charge 48V batteries and provide me with 240VAC split phase output suitable for large motor loads in one unit.
I realize the 6000EX can do this with solar charging from PV panels from 120VDC to 480DC, but winter is upon us, and some days won't have enough solar available. However I can make my own DC current with rectification of the generator input (similar to how a car makes 12VDC voltage from an AC alternator).

• So I want to convert the 120VAC to 120-170VDC from the generator (taking the RMS into account), have it charge the batteries thru one of the existing solar inputs. (i.e. the 120VAC from the generator is converted to 120-170VDC, then put in as if it were a solar DC charging input)
• Can the inverter tell the difference between rectified (converted) DC and solar created DC?

It seems to me that given solar inputted DC power is notoriously intermittent and massively variable with weather, clouds, time of day and year etc... a rectified/converted AC to DC source coming along the DC input would be a lot more stable that photon generation; especially when there are no photons available.
Would the Rectified DC need to be smoothed or would the 60Hz "wobbles" be an issue?
Biggest question: Has anyone actually ever used or tried this?

Cheers all!
Gal

 

[timselectric]

I plan on doing the same thing.
I believe it would work fine. As long as there's no other connection (electrically) between the two AC systems. (Other than ground)
That being said, be mindful that you will be voiding the warranty. By using in a way that it was not intended for.

 

[galstaf]

The rectification can be "lumpy" (bottom graph dotted line) or "Smoothed" with a capacitor. Either way it puts out about 170VDC from 120VAC (again RMS), which is well within the charging range of the 6000EX unit (120VDC to 480VDC charging range).
The 6000EX shouldn't care where the DC is coming from, right?
I have seen posts from others about other less capable inverters not being able to handle the 170VDC but this unit should be fine to charge the batteries, correct?

 

[Quattrohead]

In theory it should work fine.
However, I would be concerned about the MPPT not being smart enough to not pull so much current that it blows itself up.
Easy solution to test this is wire in a standard 120v bulb of say 60w and see how it responds, then up the bulb to 100/150/250w etc.
Variac would be the professional tool if you happen to have one
BTW MPPT circuits have capacitors on their input anyway so no need to add any more after the bridge.

 

[galstaf]

I plan on doing the same thing.
I believe it would work fine. As long as there's no other connection (electrically) between the two AC systems. (Other than ground)
That being said, be mindful that you will be voiding the warranty. By using in a way that it was not intended for.

I tried to google EG4 as a company, and they are their two distributors are apparently a house brand of Sig Solar.. all of it is run by the same folks. Is that correct anyone?
It is totally fine with me .. I like they are taking existing units and making improvements!

However I know from fairly extensive reading today I am not the only person needing this feature. So it would be great if they could have their inhouse R and D confirm this works and it *should* be a supported feature. (obviously as long as the user actually rectifies the power correctly!!).
So according to the videos @EthanFromSignatureSolar and Marcus(?) may be the experts on setting up the 6000EX so perhaps they could help?

Thanks all!

 

[galstaf]

In theory it should work fine.
However, I would be concerned about the MPPT not being smart enough to not pull so much current that it blows itself up.
Easy solution to test this is wire in a standard 120v bulb of say 60w and see how it responds, then up the bulb to 100/150/250w etc.
Variac would be the professional tool if you happen to have one
BTW MPPT circuits have capacitors on their input anyway so no need to add any more after the bridge.

When you say to wire in a 60W bulb, what exactly are you referring to? Where in the circuit? DC or AC?
Could you do a quick wiring diagram, take a pic and post it please?

 

[timselectric]

all of it is run by the same folks. Is that correct anyone?

Yes
EG4 is a offshoot company under Signature Solar.

 

[galstaf]

In theory it should work fine.
However, I would be concerned about the MPPT not being smart enough to not pull so much current that it blows itself up.
Easy solution to test this is wire in a standard 120v bulb of say 60w and see how it responds, then up the bulb to 100/150/250w etc.
Variac would be the professional tool if you happen to have one
BTW MPPT circuits have capacitors on their input anyway so no need to add any more after the bridge.

Actually I do have a variac that inputs 120VAC and outputs from 60VAC to 280VAC. Totally forgot about that guy!

I wonder if that would work? I will ask on the other thread.

 

[timselectric]

I'm getting lost between the threads. lol

 

[Quattrohead]

When you say to wire in a 60W bulb, what exactly are you referring to? Where in the circuit? DC or AC?
Could you do a quick wiring diagram, take a pic and post it please?

Inline between your 120v source and the bridge or after the bridge. You are just using it as a large resistor.

 

[Quattrohead]

Actually I do have a variac that inputs 120VAC and outputs from 60VAC to 280VAC. Totally forgot about that guy!

I wonder if that would work? I will ask on the other thread.

Yes that would work, but I like the bulb better because it is a higher resistance and you will see by the light given off what the MPPT is up to

 

[galstaf]

Yes that would work, but I like the bulb better because it is a higher resistance and you will see by the light given off what the MPPT is up to

I am a neophyte with these solar inverters. What exactly would be the effect on the MPPT of the 60W vs 250W incandescent bulb?
Would the MPPT be able to tell the Variac is only 2000W capable and limit itself? Could the software of the inverter be told not to draw more than a certain amount?
Would adding an appropriate breaker help (perhaps 10A)?

 

[galstaf]

I'm getting lost between the threads. lol

haha.. sorry. I was trying to keep the AC input and DC input method threads separate. I am trying to be creative, but it sure is getting confusing. ;-)

 

[Mithril]

In theory it should work fine.
However, I would be concerned about the MPPT not being smart enough to not pull so much current that it blows itself up.
Easy solution to test this is wire in a standard 120v bulb of say 60w and see how it responds, then up the bulb to 100/150/250w etc.
Variac would be the professional tool if you happen to have one
BTW MPPT circuits have capacitors on their input anyway so no need to add any more after the bridge.

Not sure what you mean here. Only thing I can think of is if you don't add enough capacitance/inductance on the DC side causing the MPPT to draw enough amps that as the voltage rises faster than it can respond it goes over total wattage capacity. Unlike solar DC there's no risk here of a AC-DC converter "pushing" too many amps. But I don't know if MTTP can deal with such fast voltage changes.

While an MTTP *might* have some input capacitors, you'd need a LOT to smooth out 10 or so amps at 120HZ!
My suggestion is would to (safely!) build the AC - DC circuit, with a PROPER DC circuit breaker rated appropriately, at minimum an inrush and noise suppression on the AC side and test with a purely resistive load, like a heater without a fan, and put a properly rated scope on the DC side to see if you've got remotely enough capacitance.