Voltage back feed. Am I toast?

MikeinIdaho · Aug 16, 2022

Switching back from off grid power to on grid, we accidentally switched on the main before switching off the dedicated solar breaker. I think my parallel EG4 6500-ex 48's are toast. One won't power up at all, even on solar power. The other will power up on solar, but gives a "6P" error. Neither working with the Lifepower4 batteries. In fact, the battery fuses trip when trying to power the "working" inverter on.

Am I out $3k, or is there an internal fuse that has tripped?

crossy · Aug 16, 2022

Oops!

Well it can do no harm to pop the lids off and look for blown fuses, although from your description of what happens when you try to power up I'm afraid you could be right. Feeding the mains up the output of an inverter not intended to grid tie is very likely to let the Magic Smoke out.

It might be worth contacting the manufacturer, some can be very helpful, particularly if you are capable of obtaining parts and making the necessary repairs yourself.

Whilst your new inverters are on order please invest in a proper transfer switch (and get it installed by a professional) so that you can't make the same mistake again.

400bird · Aug 16, 2022

crossy said:
Whilst your new inverters are on order please invest in a proper transfer switch

Seconded!
A lockout on the breakers would work too, if they are in the same panel.

sergea · Aug 16, 2022

MikeinIdaho said:
Switching back from off grid power to on grid, we accidentally switched on the main before switching off the dedicated solar breaker. I think my parallel EG4 6500-ex 48's are toast. One won't power up at all, even on solar power. The other will power up on solar, but gives a "6P" error. Neither working with the Lifepower4 batteries. In fact, the battery fuses trip when trying to power the "working" inverter on.

Am I out $3k, or is there an internal fuse that has tripped?

do you know murphy law ;-) . I hope you didn't kill your batteries too. ask your vendor the cost for a board replacement, there's nothing you can do.

RV10flyer · Aug 16, 2022

My Ronk 7205A 200A manual transfer switch is around $700 and is aluminum and well built.

chess-equality · Aug 17, 2022

The inverters got double whooped with solar and grid power?

crossy · Aug 17, 2022

RV10flyer said:
My Ronk 7205A 200A manual transfer switch is around $700 and is aluminum and well built.

Not exactly cheap, but still rather less expensive than 3 grand's worth of inverter.

upnorthandpersonal · Aug 17, 2022

crossy said:
Whilst your new inverters are on order please invest in a proper transfer switch

Thirded.

crossy said:
and get it installed by a professional

^ this.

rogerdw · Aug 26, 2022

sergea said:
ask your vendor the cost for a board replacement, there's nothing you can do.

Who are you people? Doesn't anyone make an effort to fault find before they condemm thousands of dollars worth of equipment to the bin.

Nobodybusiness · Aug 26, 2022

crossy said:
Oops!

Well it can do no harm to pop the lids off and look for blown fuses, although from your description of what happens when you try to power up I'm afraid you could be right. Feeding the mains up the output of an inverter not intended to grid tie is very likely to let the Magic Smoke out.

It might be worth contacting the manufacturer, some can be very helpful, particularly if you are capable of obtaining parts and making the necessary repairs yourself.

Whilst your new inverters are on order please invest in a proper transfer switch (and get it installed by a professional) so that you can't make the same mistake again.

Or an interlock.

Nobodybusiness · Aug 26, 2022

rogerdw said:
Who are you people? Doesn't anyone make an effort to fault find before they condemm thousands of dollars worth of equipment to the bin.

If you ran mains into an Inverter output while it was running odds are very good they are toast.

Might not be but we have seen it enough to say pretty sure.

Especially with what he is describing.

A Transfer or Interlock keeps this from happening.

OzSolar · Aug 27, 2022

So what happened here? Doesn't the the inverter have and AC Out and AC in? So rather than install a sub panel dedicated to the inverter the OP was backfeeding the main panel after he turned off the main breaker? Yikes...

Nobodybusiness · Aug 27, 2022

OzSolar said:
So what happened here? Doesn't the the inverter have and AC Out and AC in? So rather than install a sub panel dedicated to the inverter the OP was backfeeding the main panel after he turned off the main breaker? Yikes...

That’s what it appears to be..

RCinFLA · Aug 27, 2022

This is an example of HF inverter four H-bridge sinewave PWM IGBT's that had grid applied with async phasing to its AC output when inverter was active. It often also takes out the IGBT gate opto isolator drivers on backside of PCB.

Nobodybusiness · Aug 27, 2022

RCinFLA said:
This is an example of HF inverter four H-bridge sinewave PWM IGBT's that had grid applied with async phasing to its AC output when inverter was active. It often also takes out the IGBT gate opto isolator drivers on backside of PCB.

View attachment 108819

If that was the only damage probably an easy fix.
Hard to tell what else got hammered in that exchange.

Burned traces would be hard to see especially on a multilayered board..

Danke · Aug 27, 2022

RCinFLA said:
This is an example of HF inverter four H-bridge sinewave PWM IGBT's that had grid applied with async phasing to its AC output when inverter was active. It often also takes out the IGBT gate opto isolator drivers on backside of PCB.

View attachment 108819

A little nail polish and duct tape oughta do it.

crossy · Aug 27, 2022

RCinFLA said:
This is an example of HF inverter four H-bridge sinewave PWM IGBT's that had grid applied with async phasing to its AC output when inverter was active. It often also takes out the IGBT gate opto isolator drivers on backside of PCB.

View attachment 108819

Did it actually live after the repair attempt??

OzSolar · Aug 27, 2022

Biasjo said:
That’s what it appears to be..

I've been called out to troubleshoot a few projects installed by others over the years. Original installers magically went MIA when problems started. Poof... Bumped into this around 5 times if memory serves me correctly. What I learned from the factories is that it's very clear to them what happened to the product and they don't warranty it.

A few times the end user already had the repaired or replacement unit back and "just needed me to hook it up". Of course I walked away from the those projects because the owners refused to do it right.

Side note: I bet $1 the OP never returns. It would interesting to see the stats on the "one and done" posters some day.

edit to fix typo

Voltage back feed. Am I toast?

MikeinIdaho

New Member

crossy

Solar Addict

400bird

Solar Wizard

sergea

Solar Enthusiast

RV10flyer

Solar Wizard

chess-equality

Solar Enthusiast

crossy

Solar Addict

upnorthandpersonal

Administrator

rogerdw

New Member

Nobodybusiness

Collecting the leftovers of the Great Sky Reactor.

Nobodybusiness

Collecting the leftovers of the Great Sky Reactor.

OzSolar

Whatever you did, that's what you planned.

Nobodybusiness

Collecting the leftovers of the Great Sky Reactor.

RCinFLA

Solar Wizard

Nobodybusiness

Collecting the leftovers of the Great Sky Reactor.

Danke

Solar Wizard

crossy

Solar Addict

OzSolar

Whatever you did, that's what you planned.

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