Schneider BCS and XWPro

Just watched the @SignatureSolarJames video on the BCS and have a few questions:

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.

2: Trying to understand how the self consumption works for those of us not allowed to sell to grid. Is there a different wattnode than others have tired in the past to make sure sell back can never occur?

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. What happens with a generator input on the XWPro or how is a generator used?

4: Assume batteries can still be charged from
Grid when low and no Solar with this solution since there is a connection to AC1 Input
.
5: Seems the cutover time between grid and inverter is slower than what the XW can do if using it in a non BCS install.


Link to video:

ChrisG said:

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.

Click to expand...

ChrisG said:

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.

Click to expand...

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. (NEC requires the total input into a box to be 120% of the box rating (or less). If you have a 200A box and no other solar, your total input is 228.3A, and that is fine. However, if you have existing solar fed into the box, you may go over the allowed 240A.

If you do hit the 120% problem, you can solve this by landing the inverter power in the BCS (there are lugs to do it in the BCS).

I am currently investigating the Schnider and BCS for a place that has an existing string inverter and I ran into the 120% rule.

I am in the design phase and am still looking at options but currently looking at something like this:


Notice I draw two seperate 'outputs' on the BCS. Internally they are tied together, but each having their own set of lugs.

Like I said, I am still in design phase and working on figuring out all of the NEC rules so this may have some tweaks before I start the install.
I also need to study up on the Xanbus and the battery closed loop to make sure that is correct.

One thing I really like is that I am able to keep the XW PRO in the garrage but keep the BCS at the Panel & meter on the other side of the house (and outside). The BCS also solves the 120% problem for me.

Another thing I like about this set-up is that I don't have to move any of my existing circuits. If the power goes down I will be able to run anything I want.... but maybe not everything at once. If I have to, I'll stack a 2nd XW Pro in the future, but I really don't think it will be needed.

ChrisG said:

2: Trying to understand how the self consumption works for those of us not allowed to sell to grid. Is there a different wattnode than others have tired in the past to make sure sell back can never occur?

Click to expand...

I am on a sellback plan so I have not really looked into that. However, I believe there are CTs and it can be programed for zero export.

If you do need a Wattnode, you will probably need to use the insight facility (not insight home) for the extra ports.

ChrisG said:

What happens with a generator input on the XWPro or how is a generator used?

Click to expand...

When the BCS is in use, the XWPro Gen port gets repurposed as a voltage sense so it can detect the grid voltage at the BCS properly. Consequently, the Gen port is not available for generators when the BCS is used. I don't plan on getting a generator, so that is no big deal to me. (I would spend the money on more solar and batteries before I spent it on a gen set). I guess if a Generator is needed, there would need to be a transfer switch between the meter and the BCS.

ChrisG said:

4: Assume batteries can still be charged from Grid when low and no Solar with this solution since there is a connection to AC1 Input

Click to expand...

Yes.

Thank you @FilterGuy. The transfer time between grid and inverter in the BCS puzzles me a bit. Think it’s listed at 50ms but does it really matter since both grid and inverter are powering loads at the same time anyway in normal state, meaning that it would be seamless to any loads when the grid contacts open up in BCS unless AC is charging batteries via XW. It’s then the ms for the XW transfer time.

Some will need to make the choice on what to power and many need a non-critical load panel (funny we’re talking the opposite here). For example in my primary residence I have a 5 ton A/C, 4 ton A/C, 1.5 hp pool pump, and two hot water heaters. That’s a lot of power needs that would not be cost effective to try to build and power from Battery/Inverter. Same issue with Sol-Ark or EG4 18kPV.

I think you are correct, The transfer time shouldn't matter..... but I am going to have to think about that to see if there is something I am missing.

ChrisG said:

The transfer time between grid and inverter in the BCS puzzles me a bit. Think it’s listed at 50ms but does it really matter since both grid and inverter are powering loads at the same time anyway in normal state, meaning that it would be seamless to any loads when the grid contacts open up in BCS unless AC is charging batteries via XW. It’s then the ms for the XW transfer time.

Click to expand...

FilterGuy said:

I think you are correct, The transfer time shouldn't matter..... but I am going to have to think about that to see if there is something I am missing.

Click to expand...

There are two cases to consider:

1) The inverter is already supplying power to the critical load. In this case, I don't think transfer time matters. The inverter will disconnect from the grid but there is no transfer.
2) The inverter is not powering the loads when the grid goes down. In this case, the inverter has to detect the failure and spin up power. This is the transfer time that matters. It is driven completely by the inverter electronics and firmware and is unrelated to the disconnect relay.

FilterGuy said:

There are two cases to consider:

1) The inverter is already supplying power to the critical load. In this case, I don't think transfer time matters. The inverter will disconnect from the grid but there is no transfer.
2) The inverter is not powering the loads when the grid goes down. In this case, the inverter has to detect the failure and spin up power. This is the transfer time that matters. It is driven completely by the inverter electronics and firmware and is unrelated to the disconnect relay.

Click to expand...

Good point on #2 and I believe the transfer time <10ms for XW which would seamless.

So with the BCS you get:
1. Compliant disconnect
2. Compliant Transfer switch to completely bypass inverter(s)
3. Wattnode or similar to deal with sellback or not allow sell for my case and only consume(no interconnect agreements and sell back allowed)
4. Monitoring of above with insights
5. Much less complicated wiring for inverters

FilterGuy said:

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. (NEC requires the total input into a box to be 120% of the box rating (or less). If you have a 200A box and no other solar, your total input is 228.3A, and that is fine. However, if you have existing solar fed into the box, you may go over the allowed 240A.

If you do hit the 120% problem, you can solve this by landing the inverter power in the BCS (there are lugs to do it in the BCS).

I am currently investigating the Schnider and BCS for a place that has an existing string inverter and I ran into the 120% rule.

I am in the design phase and am still looking at options but currently looking at something like this:
View attachment 150337

Notice I draw two seperate 'outputs' on the BCS. Internally they are tied together, but each having their own set of lugs.

Like I said, I am still in design phase and working on figuring out all of the NEC rules so this may have some tweaks before I start the install.
I also need to study up on the Xanbus and the battery closed loop to make sure that is correct.

One thing I really like is that I am able to keep the XW PRO in the garrage but keep the BCS at the Panel & meter on the other side of the house (and outside). The BCS also solves the 120% problem for me.

Another thing I like about this set-up is that I don't have to move any of my existing circuits. If the power goes down I will be able to run anything I want.... but maybe not everything at once. If I have to, I'll stack a 2nd XW Pro in the future, but I really don't think it will be needed.


I am on a sellback plan so I have not really looked into that. However, I believe there are CTs and it can be programed for zero export.

If you do need a Wattnode, you will probably need to use the insight facility (not insight home) for the extra ports.


When the BCS is in use, the XWPro Gen port gets repurposed as a voltage sense so it can detect the grid voltage at the BCS properly. Consequently, the Gen port is not available for generators when the BCS is used. I don't plan on getting a generator, so that is no big deal to me. (I would spend the money on more solar and batteries before I spent it on a gen set). I guess if a Generator is needed, there would need to be a transfer switch between the meter and the BCS.


Yes.

Click to expand...

What was does your final layout look like now? Is it similar to what you have laid out in your diagram? I am considering doing something similar with the BCS in an off grid situation with a back up generator.

FilterGuy said:

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. (NEC requires the total input into a box to be 120% of the box rating (or less). If you have a 200A box and no other solar, your total input is 228.3A, and that is fine. However, if you have existing solar fed into the box, you may go over the allowed 240A.

If you do hit the 120% problem, you can solve this by landing the inverter power in the BCS (there are lugs to do it in the BCS).

I am currently investigating the Schnider and BCS for a place that has an existing string inverter and I ran into the 120% rule.

I am in the design phase and am still looking at options but currently looking at something like this:
View attachment 150337

Notice I draw two seperate 'outputs' on the BCS. Internally they are tied together, but each having their own set of lugs.

Like I said, I am still in design phase and working on figuring out all of the NEC rules so this may have some tweaks before I start the install.
I also need to study up on the Xanbus and the battery closed loop to make sure that is correct.

One thing I really like is that I am able to keep the XW PRO in the garrage but keep the BCS at the Panel & meter on the other side of the house (and outside). The BCS also solves the 120% problem for me.

Another thing I like about this set-up is that I don't have to move any of my existing circuits. If the power goes down I will be able to run anything I want.... but maybe not everything at once. If I have to, I'll stack a 2nd XW Pro in the future, but I really don't think it will be needed.


I am on a sellback plan so I have not really looked into that. However, I believe there are CTs and it can be programed for zero export.

If you do need a Wattnode, you will probably need to use the insight facility (not insight home) for the extra ports.


When the BCS is in use, the XWPro Gen port gets repurposed as a voltage sense so it can detect the grid voltage at the BCS properly. Consequently, the Gen port is not available for generators when the BCS is used. I don't plan on getting a generator, so that is no big deal to me. (I would spend the money on more solar and batteries before I spent it on a gen set). I guess if a Generator is needed, there would need to be a transfer switch between the meter and the BCS.


Yes.

Click to expand...

What was does your final layout look like now? Is it similar to what you have laid out in your diagram? I am considering doing something similar with the BCS in an off grid situation with a back up generator.