Help Understanding the diagrams. Schneider BCS and XW Pro Wiring..

[IdiotJeff]

I'm trying to understand how the BCS works and is wired. From what I'm gathering the BCS is a 200amp pass through for your main panel as well as the relay itself to tell the inverters grid is off and disconnect / isolate from the grid. The load however for the inverters are not handled by the BCS, but through separate wiring correct?

Looking at the diagrams I took from Schneider docs:

• Home Loads is NOT #14 right? Home loads is the output of the breakers to whatever you chose your loads to be. (Main Panel, Sub panel)
• #14 is grid pass through and power to send to inverters (Output (L1/L2) wiring to XW Pro inverter(AC1) and main AC panel) but then I thought power was being sent to the inverter from #12. Or is that only for the relay?
• Why would the right pic (Wiring Overview) show such large gauge wire going to the inverter(s), but only one of the Inverter is getting power on the right (Wiring Diagram)? Do both inverters need power supplied?

 

[IdiotJeff]

Ok stared at it a bit longer. I see that the output of the inverter AC1 go back to #14 so when the grid is off, the relay disconnects from the grid and AC1 from the inverter runs your load panel.

@Brucey are you using a BCS in your setup or off grid only?

 

[scrubolio]

I have this question to that I'd like to get confirmed by another member who has finished their system install.

According to the manual and the rep I talked to at Schneider over the phone.

There are 2 ports for both L1 and L2 at the BCS labeled in your screenshot as #14.

Port 1 of both L1 and L2 goto AC1 (GRID) of your inverter.

Port 2 of both L1 and L2 goto the Load panel.

Then the Master XW Pro's AC2 (GEN) is connected #12 in your screenshot.

The odd thing is that then the Inverter's AC OUT goes unused. The manual specifically states this in the "XW Pro Multi Unit Guide" commissioning section, but my installers would like it to be confirmed (as Schneider's manuals sometimes leave much to be desired).

 

[blerpaderpa]

I just finished my install of bcs with 1 xw- happy to answer any q’s.

 

[blerpaderpa]

I'm trying to understand how the BCS works and is wired. From what I'm gathering the BCS is a 200amp pass through for your main panel as well as the relay itself to tell the inverters grid is off and disconnect / isolate from the grid. The load however for the inverters are not handled by the BCS, but through separate wiring correct?

Looking at the diagrams I took from Schneider docs:

• Home Loads is NOT #14 right? Home loads is the output of the breakers to whatever you chose your loads to be. (Main Panel, Sub panel)
• #14 is grid pass through and power to send to inverters (Output (L1/L2) wiring to XW Pro inverter(AC1) and main AC panel) but then I thought power was being sent to the inverter from #12. Or is that only for the relay?
• Why would the right pic (Wiring Overview) show such large gauge wire going to the inverter(s), but only one of the Inverter is getting power on the right (Wiring Diagram)? Do both inverters need power supplied?

#12 is only there to tell your inverter (ac2) that the grid is on or off and maybe for voltage qualification. If grid goes out, ac1 has no way of knowing when to reconnect.

 

[Brucey]

Ok stared at it a bit longer. I see that the output of the inverter AC1 go back to #14 so when the grid is off, the relay disconnects from the grid and AC1 from the inverter runs your load panel.

@Brucey are you using a BCS in your setup or off grid only?

No BCS in my intended configurations.

 

[IdiotJeff]

I just finished my install of bcs with 1 xw- happy to answer any q’s.

Awesome, could you post some pics of your wiring and confirm my 2nd post? Meaning the inverters load side is feed back to the BCS? When the BCS sees no grid (#12) the relay opens which then puts the load on the inverters and the grid is disconnected.

Do you have one or two XP? If two, how did you wire them together to go back into the BCS.

 

[IdiotJeff]

I have this question to that I'd like to get confirmed by another member who has finished their system install.

According to the manual and the rep I talked to at Schneider over the phone.

There are 2 ports for both L1 and L2 at the BCS labeled in your screenshot as #14.

Port 1 of both L1 and L2 goto AC1 (GRID) of your inverter.

Port 2 of both L1 and L2 goto the Load panel.

Then the Master XW Pro's AC2 (GEN) is connected #12 in your screenshot.

The odd thing is that then the Inverter's AC OUT goes unused. The manual specifically states this in the "XW Pro Multi Unit Guide" commissioning section, but my installers would like it to be confirmed (as Schneider's manuals sometimes leave much to be desired).

I took it as AC1 from both inverters as the output (Load side). Otherwise why would 'home loads' be part of that circuit.

I don't know if that diagram supports showing all of the wiring possible on the XP Pros. I found much better docs from Schneider from 2019 for wiring the Inverters. However, the BCS came out in 2022 I believe and does not do as good of a job showing the wiring in my opinion.

Signature Solar did a good video on the BCS when it first came out. Explains about how the inverter backfeeds into the BCS.

 

[IdiotJeff]

#12 is only there to tell your inverter (ac2) that the grid is on or off and maybe for voltage qualification. If grid goes out, ac1 has no way of knowing when to reconnect.

I missed this. So that diagram I posted is not all of the wiring for suppling power to the inverter right? I don't see it anywhere. So my assumption is that it is being supplied via a 60amp breaker from your normal main panel? If the grid goes down, no AC input which is fine.

Also if you have two XP, do you need to supply with only one 60amp breaker from the panel? Or does each inverter get it's own 60amp breaker to feed power to each inverter?

 

[BentleyJ]

Been following this post today. Not sure exactly if there is a question here or exactly what it is. On one hand its mentioned Sig Solar did a good video but then there was a question of how to feed 2 inverters with 1 breaker when the diagram shows 2, one 60A breaker for each inverter. Also what did you mean by Panel? The breaker panel or the BCS. The inverters are fed from the BCS.

Is there going to be a PDP?

I believe I can help if specific questions are asked.

 

[IdiotJeff]

Been following this post today. Not sure exactly if there is a question here or exactly what it is. On one hand its mentioned Sig Solar did a good video but then there was a question of how to feed 2 inverters with 1 breaker when the diagram shows 2, one 60A breaker for each inverter. Also what did you mean by Panel? The breaker panel or the BCS. The inverters are fed from the BCS.

Is there going to be a PDP?

I believe I can help if specific questions are asked.

For me, I'm trying to understand how the Load side of the inverter is wired to the BCS and how the GRID side is wired to the inverters from the BCS the two diagrams I posted. I "think" I have the load side figured out.

When I read the two different diagrams I posted, I believe the load is shown in the Wiring Diagram. But I do not see how the supply (grid) from the BCS to the inverter is shown in either diagram, wiring or overview.

No PDP.

Those are two different diagrams I made into one pic as they seemed to have the best documentation.

 

[IdiotJeff]

@FilterGuy posted his potential setup. Did you ever end up going with a BCS?

Post in thread 'Schneider BCS and XWPro'

May 24, 2023

1: assume this is really only needed or good practice if you need more than one XW Pro. Assume you can use start with one XW and grow with BCS over time.

3: Seems to really simplify wiring since only AC1 input is wired up from inverter(s) to main or backed up panel depending on solution.

There is a potential gotcha of landing the inverter in the main breaker box.
1) What is your main breaker box rated for?
2) Do you have any existing solar already going into your main breaker box?

The reason I ask is that it is possible to hit the 120% rule on the main breaker box...

• FilterGuy

 

[blerpaderpa]

Their diagrams are pretty incomplete- you basically have the 2 best diagrams of how the connections work. if you read the BCS manual, the little fused L1/L2 wires from the BCS are called 'AC Sense Wires' and are connected to AC2.

The XW AC1 port goes to a 60A breaker, and then can land directly on the BCS bus at #14. These wires are how the XW charges the batteries from grid and how it backfeeds when doing grid sell or backup power. It's the line and the load for the XW. It's bidirectional. AC Out does not get used. Personally, i went XW AC1 -> 60a breaker in MiniPDP panel -> 60A breaker in critical loads panel (essentially bidirection breaker in the panel). You have to make sure your critical load panel can handle grid +backfed breaker (120% rule) in this situation.

No additional connection from the critical loads panel to the BCS for my situation. I think the easiest way to wire it would be going BCS directly to both the backup panel as well as the XW's as they show in their picture.

I'm not sure on the wiring of the multi-unit setup, but @BKY2003 did one recently.

 

[blerpaderpa]

There is actually one more diagram in the multi-unit design manual and some good info on commissioning in multi-unit setup (I also used their checklist for the single-unit setup)

https://solar.se.com/us/wp-content/uploads/sites/7/2022/09/XW-Pro-Multi-Unit-Guide-990-91373B.pdf

 

[IdiotJeff]

Their diagrams are pretty incomplete- you basically have the 2 best diagrams of how the connections work. if you read the BCS manual, the little fused L1/L2 wires from the BCS are called 'AC Sense Wires' and are connected to AC2.

Thank you so much! I'm a picture guy! Reading ?!

At least I've confirmed they are incomplete in someone else's mind!

 

[IdiotJeff]

You have to make sure your critical load panel can handle grid +backfed breaker (120% rule) in this situation.

Can you elaborate more on this? I think i get the rule on the breaker 80%, but grid + backfeed 120%? So what your saying is the BCS is passing the GRID through and at the same time, the inverter is also passing 60amps through at the same time in normal Grid on operation? I thought the 60amps from the inverter only came on when the relay switched based on the inverter sensing no more GRID from the BCS (ATS)?

My Critical load panel is going to be my entire 200AMP house panel. Why I have a 200AMP panel on my little 2000 sqft house is beyond me, but it is what is there.

Reading Filterguy post above, if I use the BCS the 120% rule wont apply.

 

[blerpaderpa]

going to the bcs is probably the best way but you have to observe the feeder tap rule because that wire from the bcs to the 60a xw breaker to the xw is unprotected between the bcs and 60a breaker and is capable of 200a.

If you go direct to your panel, you need to make sure the 120% rule is observed even if you only use backup mode. I think the way around that is to use an interlock on the panel that only allows either grid or inverter. My 200a panel is rated for 225a which is fine dor the additional 60a from the xw

 

[WireMania]

If you use the BCS as service entrance will you be able to back-feed the noncritical panel with excess power and not feed the grid?

 

[blerpaderpa]

if you're backfeeding while the grid is up, you can always have spikes of power going back out to the grid- you need to have an interconnect when yo'ure doing grid sell with the BCS. If you're using the BCS WattNode, and it's wrapped around the incoming service conductors, your non-critical loads panel will be included in the zero-sell loads that your inverter is powering. If the power goes out, your non-critical loads panel will not be energized.

If you use the BCS as service entrance will you be able to back-feed the noncritical panel with excess power and not feed the grid?

 

[IdiotJeff]

..

 

[IdiotJeff]

if you're backfeeding while the grid is up, you can always have spikes of power going back out to the grid- you need to have an interconnect when yo'ure doing grid sell with the BCS. If you're using the BCS WattNode, and it's wrapped around the incoming service conductors, your non-critical loads panel will be included in the zero-sell loads that your inverter is powering. If the power goes out, your non-critical loads panel will not be energized.

When you say interconnect, you mean the agreement with the poco right? I have that already for my current solar setup (enphase).