Schneider XW PRO Settings – fine tuned

[Philip53]

As I have said in previous posts, I was continuing to work on my 'Pro' settings to reduce sell cycling & such. Unfortunately, I have had very few sunny days where I could get repetitive results from my settings. I really appreciate everyone's input in this and other similar threads, but I think I am done at this time - at least for a while. Here is a screenshot of my best day yet. Also I have listed some other data from this day, along with settings for my CC's. I have one XW6848 Pro, 3 - 100/50 CC's, 430ah lithium battery bank, 10.4kw PV.

This is a hybrid set up, grid connected and I am aiming for as high a sell to grid as possible. I have the inverter set for max sell amps. The inverter powers my home critical loads through a sub panel, with about an 800 watt load during most of the day. Routinely, during most of the day, I see in slight excess of 6kw selling back to the grid (including of course, the current critical loads).

EDIT: I see that I neglected in include here that my Grid Support Voltage is set at 53.6v. This setting guarantees that the battery voltage never reaches the 55.5 volts that the CC's are set for, but these settings do allow the CC's to continue to operate at their max output watts (dependent upon sun irradiance, of course).

Battery Summary chart below.
Total PV produced 53kwh
Battery chg. 1.9kwh
Battery discharge .268kwh
Batt chg/PV output 3.6% (cycled 3.6% PV production through battery bank - mostly, I think to bring up resting batt voltage to CC charging specs, very little sell cycling through the day)


CC settings
Bulk 55.5v
Absorb 55.5v
Float 55.5v

Resting battery voltage 53.55 (average)

There was a tremendous amount of trial and error to arrive at what appears to be 'random' settings. If the CC settings were any less, the output from the solar panels would be reduced from full capacity. I had adjusted the settings to allow as much charge time as possible through the day, with float only happening on some days near the end of solar radiance. The 55.5v float still allowed some some current to be sold to grid.
This day was sunny all day, no clouds.

 

[hogback]

Seems high for float....

 

[Philip53]

Seems high for float..

Yes, it does, but remember this is for the charge controllers. I have adjusted the system settings so that on most days it does not even go into float (stays in absorb), and if it does go into float, it is only for a short time. My system is grid tied, and I can still get some sell PV under float, with this setting.

 

[hogback]

I see. I think.

 

[GRMRC]

Yes, it does, but remember this is for the charge controllers. I have adjusted the system settings so that on most days it does not even go into float (stays in absorb), and if it does go into float, it is only for a short time. My system is grid tied, and I can still get some sell PV under float, with this setting.

Do you understand what condition the CC needs to see with the batteries for it to enter float?
My guess is no, based on some of the explanations above.
I would suggest taking the others advice about float being too high.

 

[Philip53]

Do you understand what condition the CC needs to see with the batteries for it to enter float?
My guess is no, based on some of the explanations above.
I would suggest taking the others advice about float being too high.

Hey, thanks for your comments. In this case, my proven & observable results show that float only activates after the max time limit that I set in the CC's for the absorb charge. On most every sunny day to this date, the float does not activate, or if it does, as I stated above, it is for a very short time. My goal is to have as much grid sell as possible. With a lower float level setting, no grid sell activates after float has been activated. I can see no 'harm' in having my float set at the same level as my bulk and charge. If you think this is bad, I really would like to hear why. With these settings, during the charging day, the direct battery reading with max solar PV is 54.6v, for approx. 4 hours. For the balance of the charging day, the battery reading is 54.3v. The resting battery voltage 4 hours after last PV charge is 53.5. I am a believer in not charging to 100%, nor going below 25%, although not everyone thinks this lower battery 'use' is necessary, or prudent.

These CC settings give me a very stable charge/grid sell during the day. I would love to hear any suggestions that I could use to improve on this.

FYI: I do not have my inverter charger activated, and it is set at 2-stage, for the rare occasion when it will be used.

 

[GRMRC]

Hey, thanks for your comments. In this case, my proven & observable results show that float only activates after the max time limit that I set in the CC's for the absorb charge. On most every sunny day to this date, the float does not activate, or if it does, as I stated above, it is for a very short time. My goal is to have as much grid sell as possible. With a lower float level setting, no grid sell activates after float has been activated. I can see no 'harm' in having my float set at the same level as my bulk and charge. If you think this is bad, I really would like to hear why. With these settings, during the charging day, the direct battery reading with max solar PV is 54.6v, for approx. 4 hours. For the balance of the charging day, the battery reading is 54.3v. The resting battery voltage 4 hours after last PV charge is 53.5. I am a believer in not charging to 100%, nor going below 25%, although not everyone thinks this lower battery 'use' is necessary, or prudent.

These CC settings give me a very stable charge/grid sell during the day. I would love to hear any suggestions that I could use to improve on this.

FYI: I do not have my inverter charger activated, and it is set at 2-stage, for the rare occasion when it will be used.

From the SCC Operating Manual.
<snip>
The charge controller transitions to the float stage if either of the following two
conditions are met:

The charge current into the batteries falls below the exit current threshold, which is
equal to 2% of the programmed battery capacity (for a 500 amp- hour battery bank,
this would be 10 amps), for one minute.

The charge controller has been in absorption for the programmed maximum
absorption time limit. The default is three hours, but the time limit is programmable
from one minute to eight hours.
<snip>

 

[Philip53]

Yes, my absorb is set for 8hrs.

Several folks here, in an effort to continue grid sell capability after going into float, have set their CC recharge voltage high, in order to trigger a new charge cycle. My 'high' float voltage has the same result, except it is immediate - not waiting for the batt voltage to drop to trigger a new charge cycle. Before I had gotten to my current CC settings, and with a more 'conservative' float voltage setting, and while watching my three CC's when they transitioned into float, the CC's output wattage dropped dramatically. By increasing this float setting higher (to 55.5v, I was able to observe the CC output wattage increase to it's maximum (allowed by sun irradiance). Granted, I do achieve very little increased sell watts due to this being late in the day, but compounded over many days and years, it will make a difference. And, I just could not stand having some sun out there, with very little to no capture of it.

 

[GRMRC]

Yes, my absorb is set for 8hrs.

Several folks here, in an effort to continue grid sell capability after going into float, have set their CC recharge voltage high, in order to trigger a new charge cycle. My 'high' float voltage has the same result, except it is immediate - not waiting for the batt voltage to drop to trigger a new charge cycle. Before I had gotten to my current CC settings, and with a more 'conservative' float voltage setting, and while watching my three CC's when they transitioned into float, the CC's output wattage dropped dramatically. By increasing this float setting higher (to 55.5v, I was able to observe the CC output wattage increase to it's maximum (allowed by sun irradiance). Granted, I do achieve very little increased sell watts due to this being late in the day, but compounded over many days and years, it will make a difference. And, I just could not stand having some sun out there, with very little to no capture of it.

Given that your bulk, absorption and float are the same voltage it doesn’t really matter how many hours you set the absorption time out for.
Bulk is constant current.
Absorption transitions from constant current to constant voltage.
Float is constant voltage.

 

[lopezv]

Yes, my absorb is set for 8hrs.

Several folks here, in an effort to continue grid sell capability after going into float, have set their CC recharge voltage high, in order to trigger a new charge cycle. My 'high' float voltage has the same result, except it is immediate - not waiting for the batt voltage to drop to trigger a new charge cycle. Before I had gotten to my current CC settings, and with a more 'conservative' float voltage setting, and while watching my three CC's when they transitioned into float, the CC's output wattage dropped dramatically. By increasing this float setting higher (to 55.5v, I was able to observe the CC output wattage increase to it's maximum (allowed by sun irradiance). Granted, I do achieve very little increased sell watts due to this being late in the day, but compounded over many days and years, it will make a difference. And, I just could not stand having some sun out there, with very little to no capture of it.

Enhanced Grid Support DOES work when using a Schneider MPPT charge controller that can communicate with the XW inverter via zanbus. It will NOT work if you are using equipment which does not communicate with the XW.

The inverter needs to run a TEST in standard grid support mode BEFORE it will switch to ENHANCED GRID SUPPORT MODE and allow the MPPT controller to manage the SELL voltage and amps to sell to the grid.

That test is conducted by the inverter at MAX SELL AMPS.

What happens in some systems that have small battery banks is that the batteries cant sustain voltage (big voltage drop occurs) when the inverter tries to push full sell amps to the grid. The voltage drop triggers the inverter to STOP SELLING and start to recharge the batteries. This cycling is endless due to the test never completing and the inverter NEVER switching into Enhanced Grid Support mode.

What people have been doing as a work around is lowering the sell voltage to just above the battery bank resting voltage and using all available PV watts, regardless of where the MPPT controller is in the charge cycle, to sell to the grid. While this works, it is NOT ideal. (NOTE: This is the only option if your WX and MPPT controller do not communicate).

What people with smaller battery banks should TRY is the following:

- Set MPPT FLOAT to 54.4v (for 48v LiFePO4)
- Set Absorption to 56.8+ v (or whatever you prefer for charging) and limit TIME to prevent over volt shutdown risk on BOTH the MPPT charger AND the inverter (the absorption setting MUST be the same in order for the inverter to switch to enhanced grid support)

- Set the SELL AMPS LOW... maybe around 5-10A.
- Set inverter SELL VOLTS to 65v (all this does is tell the inverter to use enhanced grid support)
- Set SELL BLOCK START to some time just after sundown
- Set SELL BLOCK END to some time just after sunrise
- Start the system and LET IT RUN.
- It may help to run the initial SELL test during max PV availability
- After the inverter sells power to the grid at its max for some time (I dont know how long) you should start to see the power being sold to the grid to become aligned with what yhe PV is providing and the use of the batteries will slowly taper down to no draw. AT THAT POINT, youre in ENHANCED GRID SUPPORT MODE.

Afterward, you can try increasing the MAX SELL AMPS on the inverter (AC) to whatever your MPPT CHARGE CONTROLLER can provide (DC output) at max PV.

From that point on, the inverter should work as follows:

- Sun comes up, batteries get charged up.
- INVERTER SELLS excess DC output from the MPPT controller to grid if excess DC output from PV is available to first manage loads, complete bulk, absorb charge and maintain float of the batteries.
- Once charged, the batteries should only be discharged in very small amounts to stabilize the AC sell function throughout the day once in FLOAT.

KEY TAKAWAYS:
- If you do not match the Absorption voltage settIngs between the inverter AND the MPPT charge controller, the inverter will NEVER swichb5\ to Enhanced Grid Support. (SEE PAGE 101 of the 2023 release of the XW OPERATION GUIDE)
- If you have a small battery bank and set the sell amps too high, the inverter may never go into Enhanced Grid Support mode.
- If you do not set the sell voltage in the inverter to 65v (or at least above the "Equalize" volts setting (as per manual)), the inverter may never go into ENHANCED grid support mode.
- If the XW isnt able to sell to the grid at MAX amps for a sufficient amount of time before dropping below sell voltage/SOC the XW may never switch to Enhanced Grid Support mode.

The sell function may work if you set the sell voltage just above float/rest voltage, but it is operating in BASIC GRID SUPPORT which is NOT the sam3 as ENHANCED GRID SUPPORT.

 

[GRMRC]

Enhanced Grid Support DOES work.

The documentation on how to correctly set it up SUCKS.

The inverter needs to run a TEST in standard grid support mode BEFORE it will switch to ENHAMNCED GRID SUPPORT MODE and allow the MPPT controller to manage the SELL voltage and amps to sell to the grid.

That test is conducted by the inverter at MAX SELL AMPS.

What happens in some systems that have small battery banks is that the batteries cant sustain voltage (big voltage drop occurs) when the inverter tries to push full sell amps to the grid. The voltage drop triggers the inverter to STOP SELLING and start to recharge the batteries. This cycling is endless due to the test never completing and the inverter NEVER switching into Enhanced Grid Support mode.

What people have been doing as a work around is lowering the sell voltage to just above the battery bank resting voltage and using all available PV watts, regardless of where the MPPT controller is in the charge cycle, to sell to the grid. While this works, it is NOT ideal.

What people with smaller battery banks should TRY is the following:

- Set MPPT FLOAT to 54.4v (for 48v LiFePO4)
- Set Absorption to 14.2+ v and limit TIME to prevent over volt shutdown risk on BOTH the MPPT charger AND the inverter (the absorption setting MUST be the same in order for the inverter to switch to enhanced grid support)

- Set the SELL AMPS LOW... maybe around 5-10A.
- Set inverter SELL VOLTS to 65v (all this does is tell the inverter to use enhanced grid support)
- Set SELL BLOCK START to some time just after sundown
- Set SELL BLOCK END to some time just after sunrise
- Start the system and LET IT RUN.
- After the inverter sells power to the grid at its max for some time (I dont know how long) you should start to see the power being sold to the grid to become aligned with what yhe PV is providing and the use of the batteries will slowly taper down to no draw. AT THAT POINT, youre in ENHANCED GRID SUPPORT MODE.

Afterward, you can try increasing the MAX SELL AMPS on the inverter (AC) to whatever your MPPT CHARGE CONTROLLER can provide (DC output) at max PV.

From that point on, the inverter should work as follows:

- Sun comes up, batteries get charged up.
- MPPT switches to FLOAT
- INVERTER SELLS available DC output from the MPPT controller to grid (after supporting loads).
- The batteries will only be used in small amounts to stabilize the AC sell function throughout the day.

KEY TAKAWAYS:
- If you do not match the Absorption voltage settIngs between the inverter AND the MPPT charge controller, the inverter will NEVER swichb5o Enhanced Grid Support.
- If you have a small battery bank and set the sell amps too high, the inverter will never go into Enhanced Grid Support mode.
- If you do not set the sell voltage in the inverter to 65v, the inverter will never go into ENHANCED grid support mode.

The sell function may work if you set the sell voltage just above float/rest voltage, but it is operating in BASIC GRID SUPPORT which is NOT the sam3 as ENHANCED GRID SUPPORT.

We all trust that you have provided feedback to Schneider about your “process” so they can update their documentation.

 

[Philip53]

Very interesting @lopezv, and thanks for the post.

I finally have my setup working very good, but I will try your method/instructions soon.

You have mentioned that the inverter charger and MPPT's must have the same charge settings. Is that necessary even when the inverter charger remains off - I have not used the inverter charger since I replaced my original XW with the Pro several months ago? Or is it simply necessary to allow the Enhanced feature to 'work'.

 

[BentleyJ]

Thanks for posting, good information. Hope one of the other forum members that had issues with Enhanced Grid Sell can verify these settings will work as described.

 

[lopezv]

Very interesting @lopezv, and thanks for the post.

I finally have my setup working very good, but I will try your method/instructions soon.

You have mentioned that the inverter charger and MPPT's must have the same charge settings. Is that necessary even when the inverter charger remains off - I have not used the inverter charger since I replaced my original XW with the Pro several months ago? Or is it simply necessary to allow the Enhanced feature to 'work'.

Hi Philip53,
I dont know if it matters if the inverter charger is set to "off" or not. I suspect the settings need to be the same regardless since it appears to merely be a parameter used by the programming.

All I found in some schneider supplemental documentation was a single statement indicating that the absorption settings need to be the same in order for Enhanced Grid Support to work.

Would be interested to hear if your able to get the enhanced grid support function to work for you after trying the process above.

 

[lopezv]

We all trust that you have provided feedback to Schneider about your “process” so they can update their documentation.

done. thanks for the suggestion.

 

[GRMRC]

Thanks for posting, good information. Hope one of the other forum members that had issues with Enhanced Grid Sell can verify these settings will work as described.

I believe the OP has given feedback to Schneider on his “process”. I would anticipate if Schneider deems it useful they will surely update their documentation. Until then….

 

[lopezv]

All,

I just learned that some of the information noted in my initial post IS stated in the latest version of the XW operation manual (eg, the need to have absorb voltages identical in both the XW and MPPT controller).

Available on the Schneider website:
Release date: July 2023
Version: 990-91402D
Page 101 of the manual explains Enhanced Grid Support as per the post above (now slightly edited to highlight this)

Please note, however, that the issue with sell/charge cycling due to small battery bank size is not addressed in the operation manual and is supposedly being explored by Schneider support.