What size Breaker in your AC Panel fed from Solar Inverter

I am totally off grid.  With my current old system the inverter feeds the main 100 Amp breaker in the cabin panel via #6 conductors in conduit.  I am upgrading my solar system and my new 6000W Inverter will limit output current to 42A continuous (–90A surge).  I know the 100 Amp breaker in my panel is oversized. My panel is a Federal Pioneer (Canadian - not the same as the US version with issues) the 100 Amp main breaker cannot be swapped out.

I would still like to get the breaker in the panel to the correct size which I believe should be a 60 Amp breaker but would need to do a panel upgrade to go to either a 60 Amp main breaker or a 60 Amp backfeed breaker.  The new 100 Amp panels allow you to swap out the main breaker so could put a 60 Amp there.

Wondering how others off grid have their panel and breakers wired?

Jon Bee wrote:I am totally off grid.  With my current old system the inverter feeds the main 100 Amp breaker in the cabin panel via #6 conductors in conduit.  I am upgrading my solar system and my new 6000W Inverter will limit output current to 42A continuous (–90A surge).  I know the 100 Amp breaker in my panel is oversized. My panel is a Federal Pioneer (Canadian - not the same as the US version with issues) the 100 Amp main breaker cannot be swapped out.

I would still like to get the breaker in the panel to the correct size which I believe should be a 60 Amp breaker but would need to do a panel upgrade to go to either a 60 Amp main breaker or a 60 Amp backfeed breaker.  The new 100 Amp panels allow you to swap out the main breaker so could put a 60 Amp there.

Wondering how others off grid have their panel and breakers wired?

It's the breaker at the inverter that needs to be sized correctly not the one in the panel. Leave the 100 amp in place and make sure the inverter breaker is small enough to trip at less than 80 percent of 60 amps (6 gauge wire) or the inverter cannot put out more than that. You have to have a sized breaker but the ESA is looking for it at source not at destination. That is based on all the installations I have ever done in Ontario.
Cheers, David

David Baillie wrote:

Jon Bee wrote:I am totally off grid.  With my current old system the inverter feeds the main 100 Amp breaker in the cabin panel via #6 conductors in conduit.  I am upgrading my solar system and my new 6000W Inverter will limit output current to 42A continuous (–90A surge).  I know the 100 Amp breaker in my panel is oversized. My panel is a Federal Pioneer (Canadian - not the same as the US version with issues) the 100 Amp main breaker cannot be swapped out.

I would still like to get the breaker in the panel to the correct size which I believe should be a 60 Amp breaker but would need to do a panel upgrade to go to either a 60 Amp main breaker or a 60 Amp backfeed breaker.  The new 100 Amp panels allow you to swap out the main breaker so could put a 60 Amp there.

Wondering how others off grid have their panel and breakers wired?

It's the breaker at the inverter that needs to be sized correctly not the one in the panel. Leave the 100 amp in place and make sure the inverter breaker is small enough to trip at less than 80 percent of 60 amps (6 gauge wire) or the inverter cannot put out more than that. You have to have a sized breaker but the ESA is looking for it at source not at destination. That is based on all the installations I have ever done in Ontario.
Cheers, David

The guys doing my solar installation said pretty much what you did.  They will be limiting the current the inverter generates so technically it's safe but I thought code would still want to see the breaker in the panel sized for the #6 conductor coming in from the inverter so would need a 60 Amp breaker in the panel.  I have some other new wiring in the cabin that I will be getting a permit for so an inspector may flag that.  And to complicate things I would need to get the old Federal Pioneer panel changed out to go to a 60 Amp breaker because the 100 Amp main breaker in there now cannot be changed.  Might be simplest to leave the old panel in and skip the permit for the new wiring that I did.  I am in Ontario as well.

If you can do it yourself, a panel change is not difficult, especially in a small cabin with hopefully not a ton of circuits. The cost then is ~the price of the panel & breakers plus a day of work in the dark (by flashlight usually). If you have some basic tools and some knowledge of how to wire a panel it’s pretty easy, actually kinda relaxing and fun.

Of course, if you don’t know how to do it and don’t feel confident you could learn, then don’t, as it could be dangerous/hazardous.

Ned Harr wrote:If you can do it yourself, a panel change is not difficult, especially in a small cabin with hopefully not a ton of circuits. The cost then is ~the price of the panel & breakers plus a day of work in the dark (by flashlight usually). If you have some basic tools and some knowledge of how to wire a panel it’s pretty easy, actually kinda relaxing and fun.

Of course, if you don’t know how to do it and don’t feel confident you could learn, then don’t, as it could be dangerous/hazardous.

Twenty five years ago I had a cabin built and I wired the whole thing plus installed the panel and mast myself. Manitoba Hydro inspected it and passed it. Sold that place two summers ago and got this new cabin we are in near Kenora.  With this new (40 year old) cabin, I had an addition built last fall and I wired all of the new circuits for it.  Now I figured I'd get an Electrician to get a permit and do the panel replacement and get my wiring inspected at the same time.  I'm going that route to make sure I never have any issues with the insurance company (and piece of mind - mostly for my wife).  But I also don't want to have an inspector looking at any existing wiring (not that I anticipate problems).  

So I either leave the old panel and just add breakers for my new circuits and not worry about the 100 Amp breaker being over-sized or go the other route with permit/electrician/new panel with 60 Amp breaker.  Or the third option, do the panel myself (and tell my wife an electrician did it).

Jon Bee wrote:

Ned Harr wrote:If you can do it yourself, a panel change is not difficult, especially in a small cabin with hopefully not a ton of circuits. The cost then is ~the price of the panel & breakers plus a day of work in the dark (by flashlight usually). If you have some basic tools and some knowledge of how to wire a panel it’s pretty easy, actually kinda relaxing and fun.

Of course, if you don’t know how to do it and don’t feel confident you could learn, then don’t, as it could be dangerous/hazardous.

Twenty five years ago I had a cabin built and I wired the whole thing plus installed the panel and mast myself. Manitoba Hydro inspected it and passed it. Sold that place two summers ago and got this new cabin we are in near Kenora.  With this new (40 year old) cabin, I had an addition built last fall and I wired all of the new circuits for it.  Now I figured I'd get an Electrician to get a permit and do the panel replacement and get my wiring inspected at the same time.  I'm going that route to make sure I never have any issues with the insurance company (and piece of mind - mostly for my wife).  But I also don't want to have an inspector looking at any existing wiring (not that I anticipate problems).  

So I either leave the old panel and just add breakers for my new circuits and not worry about the 100 Amp breaker being over-sized or go the other route with permit/electrician/new panel with 60 Amp breaker.  Or the third option, do the panel myself (and tell my wife an electrician did it).

Does your inverter have an over current breaker for AC out? If not install a 60 amp disconnect near the inverter and leave the 100 amp panel in place and add circuits to it. if you pull the permit as a homeowner in ontario and the ESA inspects it and approves it there is legally no difference than if an electrician did it. For resale and relationship peace of mind I would pull the permit. I've never had grievances with the ESA guys and have had them flag some major boo boos along the way.  

David Baillie wrote:

Jon Bee wrote:

Ned Harr wrote:If you can do it yourself, a panel change is not difficult, especially in a small cabin with hopefully not a ton of circuits. The cost then is ~the price of the panel & breakers plus a day of work in the dark (by flashlight usually). If you have some basic tools and some knowledge of how to wire a panel it’s pretty easy, actually kinda relaxing and fun.

Of course, if you don’t know how to do it and don’t feel confident you could learn, then don’t, as it could be dangerous/hazardous.

Twenty five years ago I had a cabin built and I wired the whole thing plus installed the panel and mast myself. Manitoba Hydro inspected it and passed it. Sold that place two summers ago and got this new cabin we are in near Kenora.  With this new (40 year old) cabin, I had an addition built last fall and I wired all of the new circuits for it.  Now I figured I'd get an Electrician to get a permit and do the panel replacement and get my wiring inspected at the same time.  I'm going that route to make sure I never have any issues with the insurance company (and piece of mind - mostly for my wife).  But I also don't want to have an inspector looking at any existing wiring (not that I anticipate problems).  

So I either leave the old panel and just add breakers for my new circuits and not worry about the 100 Amp breaker being over-sized or go the other route with permit/electrician/new panel with 60 Amp breaker.  Or the third option, do the panel myself (and tell my wife an electrician did it).

Does your inverter have an over current breaker for AC out? If not install a 60 amp disconnect near the inverter and leave the 100 amp panel in place and add circuits to it. if you pull the permit as a homeowner in ontario and the ESA inspects it and approves it there is legally no difference than if an electrician did it. For resale and relationship peace of mind I would pull the permit. I've never had grievances with the ESA guys and have had them flag some major boo boos along the way.  

Thank you David and Ned for the great feedback.  This is exactly the kind of information I was looking for.  Having only owned this cabin for one full summer and new to all things off grid, I am on a steep learning curve.  What I am finding is knowing how to do AC wiring is only half the battle (or less).

No, my inverter does not have an over current breaker for AC out.  This is the solution (seems obvious now ).  I will get the Solar guys I have hired for my solar upgrade to install a 60 amp breaker on the output of the inverter and leave the 100 amp panel in place and add circuits to it.  I will also pull the permit for the new circuits I installed in the new kitchen.  Having the ESA inspect those is worth it to me.  As you said, peace of mind, insurance and resale reasons.  That's valuable feedback, hearing the ESA guys are good to work with.

I'm also still considering replacing the panel and spinning it 180 degrees in the same stud bay onto the wall directly behind it's current position.  That would take it out of the new kitchen and put it into a small utility room on the wall directly on the other side.  Then I could also get rid of the 40 year old Federal Pioneer Panel.  After taking another hard look at it, I think I would do it myself and add it to the permit.  Like I said, I have done it before and although that was 25 years ago, I am confident in doing it again, especially if it gets inspected (my boo boos get caught).  I have three quotes from electricians for that job that range from $3K to $5K all quoting it as a one day job, so there's that too.

So, if I do the new panel, do I still use a 100 Amp main breaker in the new panel if I get the 60 Amp breaker installed on the output of the inverter?  Seems like the 100 Amp main breaker really does nothing at that point.  Or I could put the 60 Amp breaker in the new panel as the main breaker and not do the one at the inverter.

Jon Bee wrote:So, if I do the new panel, do I still use a 100 Amp main breaker in the new panel if I get the 60 Amp breaker installed on the output of the inverter?  Seems like the 100 Amp main breaker really does nothing at that point.  Or I could put the 60 Amp breaker in the new panel as the main breaker and not do the one at the inverter.

First means of disconnect should be outside the cabin, not in your main panel which you’ve said is in the kitchen/will be in a utility room. Whether you keep a main breaker in the panel might be a convenience or budgetary choice, or something to decide based on off-grid expertise that I personally don’t have, but I do think your first means of disconnect needs to be outside, at least if the latest codes up there are anything like they are down here in the US.

Ned Harr wrote:

Jon Bee wrote:So, if I do the new panel, do I still use a 100 Amp main breaker in the new panel if I get the 60 Amp breaker installed on the output of the inverter?  Seems like the 100 Amp main breaker really does nothing at that point.  Or I could put the 60 Amp breaker in the new panel as the main breaker and not do the one at the inverter.

First means of disconnect should be outside the cabin, not in your main panel which you’ve said is in the kitchen/will be in a utility room. Whether you keep a main breaker in the panel might be a convenience or budgetary choice, or something to decide based on off-grid expertise that I personally don’t have, but I do think your first means of disconnect needs to be outside, at least if the latest codes up there are anything like they are down here in the US.

Yup I think that is code too in Ontario.  Will get that 60A breaker done too in the solar shed next to inverter. Then leave the 100A in the new (or old) panel.

Last piece of the puzzle - figure out what gauge wire is on the 50' run from inverter in solar shed to AC panel in cabin.  I think (hope) it's #6.  Might be #8 so may have to go with 50A breaker.  Can't get out there to confirm on that.  Still too much snow on the 5Km access road.  

Ok one more panel question. Sorry this has snowballed.  If I change out the panel, do I need to buy AFCI (Arc Fault) breakers for all bedrooms and living areas as per the code now or can I just buy new standard 15A breakers to match what was in my old panel.  Or will the ESA Inspector fail that?  

I'm sorry I am not yet a walking wire gauge calculator and my code book is not on me at the moment...my gut does tell me that you are going to need thicker wire than #6 for a 50' outdoor run, especially since you'll probably want to do it in aluminum SER cable for cost and ease-of-bending purposes.

Are you doing it in buried PVC conduit?

As for the snowball question (it's fine, keep'em coming!) assuming our codes are the same, you'll need AFCIs.

A common service call is "Hey, we just had a permitted renovation in our house that included electrical work. It passed inspection, but now we get a lot of nuisance trips of our circuits. Can you please come swap the old breakers back in?" So, hold on to your receipts and packaging for the AFCI breakers and try not to scuff them up, wink wink.

Jon Bee wrote:

Ned Harr wrote:

Jon Bee wrote:So, if I do the new panel, do I still use a 100 Amp main breaker in the new panel if I get the 60 Amp breaker installed on the output of the inverter?  Seems like the 100 Amp main breaker really does nothing at that point.  Or I could put the 60 Amp breaker in the new panel as the main breaker and not do the one at the inverter.

First means of disconnect should be outside the cabin, not in your main panel which you’ve said is in the kitchen/will be in a utility room. Whether you keep a main breaker in the panel might be a convenience or budgetary choice, or something to decide based on off-grid expertise that I personally don’t have, but I do think your first means of disconnect needs to be outside, at least if the latest codes up there are anything like they are down here in the US.

Yup I think that is code too in Ontario.  Will get that 60A breaker done too in the solar shed next to inverter. Then leave the 100A in the new (or old) panel.

Last piece of the puzzle - figure out what gauge wire is on the 50' run from inverter in solar shed to AC panel in cabin.  I think (hope) it's #6.  Might be #8 so may have to go with 50A breaker.  Can't get out there to confirm on that.  Still too much snow on the 5Km access road.  

Ok one more panel question. Sorry this has snowballed.  If I change out the panel, do I need to buy AFCI (Arc Fault) breakers for all bedrooms and living areas as per the code now or can I just buy new standard 15A breakers to match what was in my old panel.  Or will the ESA Inspector fail that?  

8 gauge copper is 40 amps. Ned is absolutely right you will need an Ac disconnect outside.

David Baillie wrote:

Jon Bee wrote:

Ned Harr wrote:

Jon Bee wrote:So, if I do the new panel, do I still use a 100 Amp main breaker in the new panel if I get the 60 Amp breaker installed on the output of the inverter?  Seems like the 100 Amp main breaker really does nothing at that point.  Or I could put the 60 Amp breaker in the new panel as the main breaker and not do the one at the inverter.

First means of disconnect should be outside the cabin, not in your main panel which you’ve said is in the kitchen/will be in a utility room. Whether you keep a main breaker in the panel might be a convenience or budgetary choice, or something to decide based on off-grid expertise that I personally don’t have, but I do think your first means of disconnect needs to be outside, at least if the latest codes up there are anything like they are down here in the US.

Yup I think that is code too in Ontario.  Will get that 60A breaker done too in the solar shed next to inverter. Then leave the 100A in the new (or old) panel.

Last piece of the puzzle - figure out what gauge wire is on the 50' run from inverter in solar shed to AC panel in cabin.  I think (hope) it's #6.  Might be #8 so may have to go with 50A breaker.  Can't get out there to confirm on that.  Still too much snow on the 5Km access road.  

Ok one more panel question. Sorry this has snowballed.  If I change out the panel, do I need to buy AFCI (Arc Fault) breakers for all bedrooms and living areas as per the code now or can I just buy new standard 15A breakers to match what was in my old panel.  Or will the ESA Inspector fail that?  

8 gauge copper is 40 amps. Ned is absolutely right you will need an Ac disconnect outside.

In addition to the 40 Amp breaker, I could also add an AC disconnect switch at the inverter (which I was told is code) but I think that is overkill.  If I add the breaker there I can power down by turning the breaker off.  For the breaker, ChatGPT told me I needed a 50 Amp breaker for 8 gauge copper on a 50 foot run and would need a 60 Amp breaker for 6 gauge copper on a 50 foot run.  But I don't trust ChatGPT.  Need to look for a code book.

Ned Harr wrote:I'm sorry I am not yet a walking wire gauge calculator and my code book is not on me at the moment...my gut does tell me that you are going to need thicker wire than #6 for a 50' outdoor run, especially since you'll probably want to do it in aluminum SER cable for cost and ease-of-bending purposes.

Are you doing it in buried PVC conduit?

As for the snowball question (it's fine, keep'em coming!) assuming our codes are the same, you'll need AFCIs.

A common service call is "Hey, we just had a permitted renovation in our house that included electrical work. It passed inspection, but now we get a lot of nuisance trips of our circuits. Can you please come swap the old breakers back in?" So, hold on to your receipts and packaging for the AFCI breakers and try not to scuff them up, wink wink.

The wire is already in place between the solar shed and the cabin. It is a Teck cable inside of a buried PVC pipe.  It is either #6 or #8.  I can't get out there yet to confirm because of the snow.  I have attached 3 photos here of my old panel and you can see that wire going to main breaker (red, black, blue).  Not sure I can change it out if it needs to be #4 because re-trenching would be a huge job - unless I can pull a new one in the same PVC pipe.  

Thanks for confirming I would need the AFCIs in the new panel to meet code.  I figured that was the case.  I also wondered if that would trigger nuisance trips.  That would be not good.  That's another reason to maybe just leave my old panel in place and add breakers for my new circuits I ran.  Hopefully my old panel would pass inspection with the new circuits if I go that route.  I've got room for about 12 new circuits in the old panel once I clean up the decommissioned ones.

I have a new question related to my original post.  Any input on this one would be greatly appreciated.

The question is on bonding.  I am trying to understand if there is a neutral to ground bond either internally in the Inverter or somewhere else in the Solar System in my solar shed.  If there is a bond there then I will need to remove the ground bond that currently exists in my AC panel in the cabin to adhere to code requirements at the panel.  

Do Solar Systems typically have a bond at the inverter?  Then not in the AC panel?

From what I understand, it is incorrect (and potentially dangerous) to have two bonds.  So if there is a bond at the Solar equipment end, then the panel in the cabin should not have a bond.  In the photo I posted above of my panel, you can see the bond strap from ground to neutral in the upper left corner.

Also, regarding my earlier question, I was able to confirm that the Teck cable running from the shed to the AC panel in the cabin has three 18 gauge wires that feed the 100Amp breaker in the panel (the cable is labelled).  So I will be installing a 50Amp breaker at the output of the inverter to protect the wire.  The cable is about 58 feet from Inverter to panel in cabin.  Thanks again for the feedback on that.

I am treating the inverter as I would the power coming from the utility, in which case you should have a disconnect immediately downstream from that but upstream from your main panel, and it is at the point of disconnect that your grounds and neutrals should be bonded. But caveat: I am not familiar with solar inverters, so my reasoning might be flawed.

But you're correct that if there is a bond at the first means of disconnect and that means is upstream from your panel, then you should remove the bonding strap in your panel.

I was able to confirm that the Teck cable running from the shed to the AC panel in the cabin has three 18 gauge wires that feed the 100Amp breaker

Did you mean 8 gauge? They look thicker, like maybe #6 or even #4, though I am not positive just from your photos. I hope they aren't 18 gauge!

PS you should take white electrical tape and wrap it around that blue wire at both ends where it terminates; neutrals should always be identified with white or gray. Even just a few rings would do the trick. Same for that second ground wire that appears to be wrapped in black (?) tape--wrap it with green electrical tape instead.

Ned Harr wrote:I am treating the inverter as I would the power coming from the utility, in which case you should have a disconnect immediately downstream from that but upstream from your main panel, and it is at the point of disconnect that your grounds and neutrals should be bonded. But caveat: I am not familiar with solar inverters, so my reasoning might be flawed.

But you're correct that if there is a bond at the first means of disconnect and that means is upstream from your panel, then you should remove the bonding strap in your panel.

I was able to confirm that the Teck cable running from the shed to the AC panel in the cabin has three 18 gauge wires that feed the 100Amp breaker

Did you mean 8 gauge? They look thicker, like maybe #6 or even #4, though I am not positive just from your photos. I hope they aren't 18 gauge!

PS you should take white electrical tape and wrap it around that blue wire at both ends where it terminates; neutrals should always be identified with white or gray. Even just a few rings would do the trick. Same for that second ground wire that appears to be wrapped in black (?) tape--wrap it with green electrical tape instead.

Thanks Ned.  Sounds like yours is done right.  I was able to talk to the installers coming next week to do the solar upgrade for me and they confirmed, the inverter being installed has a ground relay that can automatically create a neutral-to-ground bond when inverting.  This can be disabled but they will look at my panel and set it all up correctly for me.  I'd like the bonding done in the inverter - like you said, at the point of disconnect that your grounds and neutrals should be bonded.  My new 50Amp breaker at the new inverter will be my new disconnect.

They are arriving next week to install new inverter, new battery and 6 new panels with new racking.  Very excited to finally get set up properly.

Yup I goofed.  The wire is #8.  So the installers will be adding a 50Amp breaker in the solar shed at the output of the inverter to protect that wire.  

Good tips on taping those neutral and ground wires.  It confused me at first when looking at that panel.  

#8 might be a size small for a 50 ft run fused at 50A, I wonder if you could upsize, at least as a near-future project, if you can tug new through the existing pipe...but check with the installers when they're there.

Ned Harr wrote:#8 might be a size small for a 50 ft run fused at 50A, I wonder if you could upsize, at least as a near-future project, if you can tug new through the existing pipe...but check with the installers when they're there.

yeah I mentioned it to them already. They seem to think it’s OK. We’ll have another chat when they get here. The other alternative is move the entire system inside the cabin. But that would be a lot more work.

It's still good to have first means of disconnect outside, so if you're gonna move it (to shorten the wire run?) I would want to move it to the outside of an exterior wall in a weatherproof box.

Ned Harr wrote:It's still good to have first means of disconnect outside, so if you're gonna move it (to shorten the wire run?) I would want to move it to the outside of an exterior wall in a weatherproof box.

Yes I meant shorten the run by moving the batteries, inverter and controller to the inside of the cabin instead of in the solar shed that is 50 feet away, which is where my old system being replaced is located.  I would put it in a small utility room.  But again, that would be a ton more work and cabling that I don't want them to do if they say the #8 wire is fine for that run with a 50Amp breaker at the inverter.