Adding Schneider XW Pro

[GXMnow]

I don’t know anything yet about configuring the system, planning to order the PV panels the end of the month, batteries month after that.
So I expect to start it sometime in Summer 2021.
I have read GXMnow about some kind of problem with charging, but don’t understand it.

If I use my system “off grid”, I would expect there is some configuration that would cause the batteries to charge automatically, when the PV panels are receiving enough energy.

If I connect to the grid (no sell back) to obtain AC battery charging, I would expect the batteries to charge from the grid when there is no energy received by the PV panels.

But I’m just guessing here, no idea how the thing works / does not work due to software issues.

The XW-Pro is mostly an inverter. That is what it wants to do. It can charge, but it needs to be forced to charge, it won't do it on it's own. When I read all about it online before buying one, I didn't believe this limitation. I figured it was some odd setup issue. But now that I have owned it for over 8 months, I can say without a doubt that the current software mine is running will never start a charge on it's own while it is on grid. There is a setting called "Recharge Volts" The battery voltage needs to fall below that for it to start a charge cycle. But here is the problem with that. The inverter stops inverting 0.5 volts ABOVE the recharge volts setting. In my system, I set it to 50.5 volts. My AC solar is back feeding through the unit, and I turn on grid sell and load shaving at 4PM. The XW-Pro takes over from the solar as the solar fall below the power needed to run my house and it provides all of the power for my backup loads panel, plus pushing 3 amps back to my main panel which not only runs the rest of my loads over there, it is actually exporting about 500 watts out to the grid. At 9pm I have it block the grid sell, but it still keeps running all my loads in the backup panel. Depending on how much the furnace runs, it will go to about 1 am when the battery bank drops to 51 volts, and then the inverter goes into standby mode. At this point, grid power runs the house. I have the charger blocked until 8 am when sun starts hitting my solar panels again, but nothing happens. The battery voltage is still above "Recharge Volts" and it just hangs there at 51 volts. Recharge was set at 50.5 so nothing happens. Now if the grid failed, it would kick back on and run do to "Low Battery Voltage Cutoff" which I have set down to 46 volts. But obviously it won't be charging without the grid. If it does run the battery down below the recharge volts setting, it will start a charge cycle when the grid returns. This was one idea I had, just have a controller take the unit off grid each night to run down the battery. Kind of a brute force kick start. The bad part is needing to operate a 60 amp contactor all the time.

When the system is off grid, it can charge if you have AC coupled solar running into the output side of the inverter. If the solar makes more power that you are using, it will see the extra current on the output and start drawing that current to run as a charger into the batteries. I did do a short test and saw it charging at 600 watts, while my solar array was down to just making 1100 watts, and my backup loads panel was drawing the other 500 watts.

What I have been doing for now is just going into settings, and clicking on "Force Charge State (BULK)" each morning after the sun is up. I have found the Modbus command to do this, and I hope to get my PLC microcontroller to send this command for me each morning. I am hopeful that Schneider may someday fix this issue. It should be no problem to add that function in the gateway. It already has time settings for "Charge Block Start" and "Charge Block Stop". I am asking them to add a check box so when check block stop happens, you can select if you want to force it to start a bulk charge.

But the more I am looking into it, I think I am going to break down and install some DC coupled solar panels to do the battery charging. Each day, I am having to put about 7.3 kwh into the battery bank. I get over 5 sun hours most days. So I would need about 1,500 watts of solar panels. I have room for 6 panels, and I found some good deals on 305 - 370 watt panels. Best price per watt right now is on 355 watt units. 355 x 6 = 2,130 watts. 5 sun hours makes over 10 KWH. I could run the battery a bit lower each night and still get it topped up each day, and I would not be taking away from my grid tie solar, so I would be selling more power back to grid during the day, or having my grid tie help run my air conditioner more rather than charging the battery. My battery has a rated capacity of 360 AH at about 3.6 volts x 14 cells = about 18 KWH so using 10 KWH each evening would still leave a bit in reserve for a grid failure. And if the battery does run down during a long grid outage, the DC solar can charge the batteries and get me back running again.

 

[pvdude]

Thanks very much for the great explanation!
(I understood most of it)
There is an electronics surplus place here, pile’s of contactors of all types & sizes.
(I used one for a step-start circuit for a HAM radio amp I built, long ago)
So if I have to interrupt the grid/inverter connection to get charging going, I’ll build a circuit to do it.

 

[GXMnow]

My idea was to take my XW-Pro off grid from midnight until the battery voltage falls to 50 volts, below the 50.5 setting for the "Recharge Volts" so that when the charge block time ends at 9:00 am, it will start a charge cycle. There is no solar going then, so it should not cause any fault with the Enphase gear.

 

[400bird]

Exciting news!
Sorry this is just tell, no show...

I ordered a battery this morning!

When I started this project in 2020, the Bolt packs were plentiful (I called one company and there were 4 packs to choose from locally). When I was ready to purchase a month ago there were none in my nation wide search.

One just came up. The vehicle had 4 miles on it. It does have to ship freight, so it should be here late next week or early the week after.

 

[400bird]

This was one idea I had, just have a controller take the unit off grid each night to run down the battery. Kind of a brute force kick start. The bad part is needing to operate a 60 amp contactor all the time.

I believe you could use the onboard outputs of the Schneider to control this. I haven't looked into it, but that was Schneider's suggestion to me.

 

[pvdude]

Great idea about using the Auxiliary Output relay!
Looks to have many configuration options, and might be a solution to operating
a contactor.
Only 250 mills source current, but that just means I will have to operate a small relay to operate a big contactor, not a problem.

 

[400bird]

Yeah, a small relay is still less expensive than a controller.

Schneider had suggested something more like disconnecting based on low battery voltage (or maybe high batt voltage) and keeping the loads off-grid at other times. This would allow all excess AC coupled PV to charge the battery.

 

[GXMnow]

I am still on Firmware 1.03 on the XW-Pro. I just looked at the Auxiliary Relay settings, and one of the choices is (Time Of Day) So I could just have it turn off the grid input for an hour overnight. That should be enough to get the battery bank below the Recharge Volts setting. I was thinking of using a high quality SCR type solid state relay. They only need about 50 ma to turn on. If I do this, I would like to do it will an inverter though. So if it is not getting voltage from the Aux output, the grid is on. So in most possible fail conditions, the grid would be connected.

The other choices are
Low Battery Voltage
High Battery Voltage
Low Battery Temperature
High Battery Temperature
Fault
Bulk Exit
Absorption Exit
Heat Sink Over Temperature
Battery Low State Of Charge

But you can only use one of them at a time. State of charge control requires either the Battery Monitor, or a compatible BMS, which I don't have. But even that will only turn on when the state goes below a level, and back off when it goes higher again. Same issue with Low Battery Voltage control. Ideally, I want it to turn on at a time, and off at a given battery voltage. That is what I was thinking with my logic controller. But using the Time of Day function, I can use this to trigger the PLC and not have to worry about my clock going out of sync. So this is still a help.

This makes the PLC state machine very easy.
Wait for rising edge from AUX relay, set to go high at 1 am. Aux goes back low at 1:15 am
Set output to disconnect grid
Monitor battery bank voltage.
When voltage falls below 50.4 volts, Clear output to turn grid connection back on.
Go back to waiting for AUX relay input.

 

[pvdude]

I’m going to try one of these Solid State relays to control the grid connection on/off.
It is not 60A, so it is an experiment.
Hoping the inverter does not sink 60A, might draw less, will see if this thing melts.
I spent time searching through Mouser, Digikey, Allied, Newark for a SPDT SSR, but did not yet
find one that can be operated w/ 12vdc 250mills.

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[GXMnow]

In most installations, including mine, this one would work fine. The internal contactor and the maximum pass through current is 60 amps, so I would like to match that rating, but I do have mine setup and breakered down to just 20 amps now as that is my maximum back feed to the main panel. And being Crydom brand, this one will even handle it's rating, unlike the cheap ones on Amazon.

 

[pvdude]

Plan “B” is to run two of these, so as to get dual poles.
Control circuits in parallel.

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[400bird]

Ha, I had not thought of it until you mentioned running two relays to cut both legs. I would guess that cutting one leg would force the XW off grid and to open it's internal transfer relay to disconnect from the grid.

GXMnow, in firmware 1.11 there is a setting that appears to be maximum export power. The abbreviation is EPC. I need to play with it some to verify it works as I expect, because I haven't found anything about it in my reading that actually explains the function. This may help you so you don't have to power the entire critical loads/sub panel through a 20 amp breaker

 

[GXMnow]

It is a tricky matter of legality. Because I only have a 100 amp panel, and still have the 100 amp main breaker, I am limited to a back feed breaker of just 20 amps. I could set the XW-Pro (by accident) to push up to 28 amps, and the solar could push another 16 amps. That would not be good. The 120% is there for safety because it is just too easy to enter a bad value. I have the settings such that the XW only pushes back 3 amps, but the solar can still hit 16 amps. The XW is smart enough, that it only helps push any current if the back feed to the grid from the solar falls below 16 amps. But when I have heavier loads in the backup loads panel, the XW can push it's full 28 amps, I have it breakered at 30 amps. I probably should up that a little more, because I could pull the 20 from the main panel as well and get 48 amps into the sub panel from the XW. And the solar can also push 16 amps into the sub panel, bringing the total to 64 amps. This is all fine as it is a 100 amp rated panel and I am still well short of that.

 

[400bird]

I forgot about how your system was set up. I agree that you have to watch the limits of both your electrical panels and breaker.
I am back feeding into a 200 amp panel with only a 150 amp main breaker, so I have lots of headroom.

On another subject, it appears there is absolutely no hysteresis built into the battery voltage thresholds. The system spent 3.5 hours bouncing the system off the 50.5 volt limit. I need to work to integrate battery voltage to show that. But this is my energy usage while it was happening.
My normal overnight use is just under 400 watts depending on ceiling fans or whatever else might be on.

You can see on the left edge of the graph where the XW is providing all but about 60 watts of my home energy use.
Then at 10:55 the battery voltage finally fell below 50.5 volts when loaded.
Once the load was removed, all 400 watts were coming from the grid and the battery voltage recovered to a high enough level that the XW decided to pull from the battery again. And again. And again! Over and over for more than 3 hours.

You can see the 3 times last night where the XW decided to disconnect from the grid (midnight, 1:10, and 1:15 am) and the resulting qualification time.
I have not figured out where the XW will tell me why it disconnected from the grid, nothing under the "Events" tab.

I currently have the recharge voltage set to 50 volts and grid support voltage set to 50.5 volts
I am going to separate these further and see if it helps with the condition tonight.

 

[400bird]

I almost forgot, every just before it switched back to attempt grid support, it would charge the battery with 15-60 watts (from the grid) just before pulling 300.

 

[GXMnow]

To see what caused the grid disconnects, click on the green bar at the top of the Insight Local page where it says "Events". Then on the left click "Historical". My last event at the top is id25 "AI Over Frequency" on February 23 at 18:45 (6:45 PM). AI is "Anti Islanding" And over frequency claims the grid went above 62 Hz. But at the same time, the Enphase inverters did not see that. There was not enough sun, so they were not communicating anyways. But a few days later, they did see "Grid Instability" but the XW was charging at the time and did not report any error.

It appears your battery has a bit more bounce back than mine. I have seen that a few times where it is pulling a decent load and hits low voltage cut off. It will recover and go back to inverting, but if the draw is fairly low, mine won't do it. Last night, my house load at 1:30 am was only pulling 13 amps at the battery. So when it shut off at 51 volts, it stayed off. In fact, it was still right at 51 volts all the way until I started it charging again at 9:20 this morning. I also see the 0.6 amp fluctuating from + to - while it is in "Stand By" between when it is done charging, and it starts inverting to feed power to my house. Here is my battery summary from yesterday.

The night before, it ran to just after 12:30, and it stayed off until I triggered the Bulk charge at 9:15 am. After 3 PM it did a very short absorb cycle and then waited for the solar to fall below my house load. After 5:30 pm is started pushing out power. I have never figured out why I see those little spikes in the charge current, but they are real. I have heard the hum of the inverter, pulse once in a while, and when I look back, I see one of those. The two current spikes after 7 pm are the microwave oven. The current cycles where you see a bit more power for 20 minutes seems to be when the blower in the furnace runs. That is the low speed mode, when it kicks to high it pulls a bit more. At 9 pm I stop feeding back to the main panel, and it just powers the backup load panel until the battery hits 51 volts, 0.5 above the recharge volts setting. I agree, I would like to see a larger dead zone where it needs to recover further before it turns back on.

Back on March 11, I did find a time when the XW shut off while it was pulling almost 30 amps when it hit 51 volt shut down. It rebounded and turned on again after 8 minutes. Ran power at 24 amps for 2 minutes and shut off again for over an hour, and came back on again at 20 amps for 22 minutes. Then it finally quit for the night. The rebound (Hysteresis) value should be adjustable, and it is for other settings in the XW. But I have never seen anything like the cycling you are seeing. What are you seeing on the Battery Summary from the Gateway?

 

[400bird]

Wow, an actual power outage!

Funny, because I am running on some temp cells that I don't really trust so I had "back-up" mode disabled.
Power went out and I had to take a laptop out to the garage to get close enough to connect the the gateway access point.
What a pain, now I understand what you are saying!

But, the house is running on battery only right now for the first time!

As part of that the solar ramped back up after the 5 minute qualification. But the cells were already at 4.1 volts, so the pack quickly exceeded the max pack voltage and the XW disconnected (more like disabled).
In that process, trying to get the XW to resume and power the house, I cleared the fault logs. So, I have no idea why it disconnected last night.


The battery summary smooths out a lot of the noise and hours of the attempts and bouncing off the voltage limit.
But, it does still show 3 attempts in just a few minutes.

 

[GXMnow]

What is your battery setup now? 50.5 volts is my recharge setting, but I could run down to 46 without hurting anything at all. That is my storm reserve. I have 14S NMC cells. The cells are good from 3.0 to 4.2 volts. x 14 that is 42 to 58.8 for the entire pack.

If it was topping up the cells, the XW-Pro should star upping the frequency. For that to work though, you need to have the "AC Coupling" check box selected. On mine, that is on the "Advanced Features" page in the menu.

While I am in here taking screen shots, here is my events/historical page

All of the DC under volt errors were from when my BMS shut off from the bad wire on a cell.

 

[400bird]

My temporary pack is 2x 14s1p cells from an LG resu home battery/ESS. From what I have read, these are similar to the cells in the bolt. It has been a while since I did my research, I can pull up some old information if you're curious.

But, these cells were very low when I got them. I recovered them nice and slowly, they test at just over 50ah each. So I've got about 100-110 ah of storage out there. But, I am only willing to charge them at 30 amps. Discharge should be fine we'll over the 60 amps I currently have set as the limit.

The issue today was that the cells just charged to 4.1 volts and would have been at about 4.09 volts.
Then the solar kicked in and would have tried to push 80 amps into an already full battery. I am pretty sure the XW needs more time than 5 seconds to frequency shift the PV, it didn't even have the chance to smash the frequency so high it caused a disconnect

My Solar Edge inverter should do frequency shifting, I just updated the firmware and followed their directions to get everything set for rule 21.


But, I want to redo the test. Maybe tomorrow morning. The cells will be more like 3.5-3.6 volts, sun lower in the sky with my west facing panels not producing much at all. I think the cells can take some punishment if it hits max amps for a short time I am not too worked about it.

 

[GXMnow]

I have not done a long enough off grid test to see it fill up the batteries. Half my iQ7 micros went offline and the sun was dipping after 4 pm also. Next time I shut down all of the PC's (4 running now) and the Dish Hopper, the WD-TV 1T hard drive, 3T hard drive on my router, etc. I will try another power fail simulation and try to log it all.

Yes, Schneider does warn that under an AC coupled off grid situation, it will try to push all of the extra AC power into the battery for a bit before it can start adjusting. I can see that being a problem with a smaller battery bank. If they were new 100 Amp Hours of LG, cells, thy should be good, but if you are not sure, it could be trouble. My system should be fine. Even if my 360 amp hour bank is at 4.09 volts, it should still take my full 3,900 watts for a few minutes without a problem. That works out to just over 68 amps if there is no load at all in my house at solar noon on a cool day. It would take about 20 minutes to push the cells to 4.2 volts.