XW Pro Grid Support limitations?

[JBertok]

I have a pair of XW Pro 6848 in sync with the whole house on their load side.
The desire is to power the loads with prioritized available DC, and use the grid to make up the difference when batteries fall below Grid-Support voltage.
It is desired to have zero draw from the grid (AC1) when DC is available and to never back-feed to the grid.
Schneider calls this running in "Self-Consumption" mode.

The XWs are configured with the following settings:
- GRID SUPPORT is "Enabled" on both
- MAXIMUM EXPORT SELL AMPS that's supposed to throttle all export is set to "0" on both
- SELL ENABLED/DISABLE is set to "Disabled" on both
- CHARGER set to DISABLED to prevent battery charging from grid on both
- BACKUP MODE for gid-forming is set to "Enabled" on both

Any time DC voltage is high enough to enable grid support, the XWs always draw between 100 and 200 watts from the grid. It never sits at zero.
They don't seem to be able to independently regulate both phases of the output to independently reach "zero" on each leg. The result is perpetual mis-handling of export. This is a big deal since exporting without utility blessings can trigger some nasty-grams from code-enforcement.

Here are some screen shots depicting what I'm talking about:
1. despite my export being set to "0" and Sell disabled, that is apparently not enough to prevent actual export (AC L1 Current)


2. Grid current is NEVER zero. It's always taking 100-200 watts, but what's worse is that it often spikes to 700+ watts of export depending on loads:

3. Sell is set to disabled and Export current set to a maximum allowable amperage of 0.0, these number should never grow. but they always do:


Based on my understanding of the architecture of the XW's block-diagram and principles, I imagine only two possible solutions to the problem:
A. Run all loads through a 240-240/120 center tapped transformer
B. Take the XWs off-grid and use an external battery charger

Either option would be expensive in both cost and power efficiency. Anyone got a better trick up their sleeve?

 

[pvdude]

Mine also seem to "leak" some energy towards the grid.

Backup mode, grid support: enabled.
XW Pro Chargers off. (MPPT controllers charge the batteries)
Sell amps=0

I opened a case w/ Schneider tech support.
First suggestion from Schneider was to upgrade the firmware, now running Build Number 1.11.01bn49

No effect on the leakage.

Next suggestion was:
"Disable the Sell mode or set "Sell amps" at 0A so the system avoid sell back to the grid."

No effect

Next:
"Set Sell Block start at 12:00 am and Sell block end at 11:59 pm.
In this period, the sell function is not going to work.
I am going to check if the inverter always sell back a little bit to the grid no matter if sell is disable. But in this case, this value should not affect for the reason that is not a lot of energy."

No effect

Next:
"The last thing we can try is using Peak Load Shave, we set a value (example: 1amp) and the batteries are going to work without the grid. If the loads are less than 1amp, the grid is going to start operating.

The grid will charge the batteries if the voltage goes below Recharge voltage."

I did not do this, as I don't use the charger in the XW Pro, the battery manufacturer (Rolls Battery Engineering) advised me not to use the inverter for charging the FLA batteries, but to use the three-stage charging available from the Schneider Conext MPPT 100 600V Charge Controller.
This is how it has been configured since installation, works very well.
So the Peak Load Shave option was not available.

Here is what my stats look like after almost 2 years of operation:

 

[400bird]

From what I've read the XW disconnects the neutral on it's transformer when connected to the grid. As such, the grid transformer needs to deal with your imbalanced loads.
Alternatively, you could balance your loads in the breaker box.

If you're pulling 3 amps from the grid on L1 and pushing 1.4 out to the grid, what does your utility meter say is happening? I'll bet is show 1.6 amps consumption. The utility meter just has a single current coil, so it can't tell the difference between -3,+1.4 and -0.8,-0.8. it just seems the total, of 384 watts.

PVdude, I'm curious what it does when you switch to using peak load shave.

 

[JBertok]

Peak Load Shaving, I could give that a go. The battery chargers can be set to lower setpoints than the MPPTs and should accomplish the same functionality I need. I don't think I'd mind the extra work to the batteries if it accomplishes the more concerning goal of Zero-Sell. Thank you, will report back!

 

[JBertok]

Some observations to report...
I enabled both XW Pros
Enabling both battery chargers in the two XW Pros resulted in an imbalance of state condition where one XW chargers goes into absorption mode but the other XW then pushes into AC1 to try to meet the criteria of the Grid Peak Load Shave criteria, which on both XWs is set to 0 amps. So, one of the XWs is working hard to convert DC into AC, and the other one is matching those efforts converting AC into DC, but all they're ultimately doing is making heat and noise in a pointless circle of catch-22 as the battery continues to hover just above LBCO. Since the aggregated metering of both AC1 inputs is used for grid control, it does still maintain the 100-200 load on the grid, and only momentarily goes backwards with load changes or excessive 120v load imbalance.
Disabling the charger on XW Pro 2 prevents the circle of self-gratification, apparently.
Ultimately, enabling Grid Peak Load Shave didn't result in any favorable changes in functionality.

It could be accomplished in firmware with this inverter architecture, but I have yet to find a way to achieve what I want with the current 1.11.01b49

What I would ask for is easy to describe:
- Full self-consumption and zero-sell
- inverters allowed create waveform, asynchronously is acceptable, or be synchronous as long as true 100.00% net-zero
- 3 definable time windows with different priorities for each timeframe setpoints
- Off-Grid unless batteries reach recharge setpoint (5% SOC for LiFEPO4 or 50% SOC for FLA) if during top tier TOU meter rate
- Off-Grid unless batteries reach recharge setpoint (10% SOC for LiFEPO4 or 55% SOC for FLA) if during middle tier TOU meter rate
- Off-Grid unless batteries reach recharge setpoint (15% SOC for LiFEPO4 or 60% SOC for FLA) if during lowest tier TOU meter rate
- when not charging, and immediately after charging complete, disconnect from grid, or maintain true 100% net-zero
- do not arbitrarily draw 100-200 watts when battery above LBCO - I want 0.00 watts

I'm not holding my breath for this dream to come true. In the mean time, I am making plans to augments my system with external battery chargers. This utterly sucks obviously because I lose all the cool metrics of power flow data. Frustrating.

 

[Allgood-Energy]

I have a pair of XW Pro 6848 in sync with the whole house on their load side.
The desire is to power the loads with prioritized available DC, and use the grid to make up the difference when batteries fall below Grid-Support voltage.
It is desired to have zero draw from the grid (AC1) when DC is available and to never back-feed to the grid.
Schneider calls this running in "Self-Consumption" mode.

The XWs are configured with the following settings:
- GRID SUPPORT is "Enabled" on both
- MAXIMUM EXPORT SELL AMPS that's supposed to throttle all export is set to "0" on both
- SELL ENABLED/DISABLE is set to "Disabled" on both
- CHARGER set to DISABLED to prevent battery charging from grid on both
- BACKUP MODE for gid-forming is set to "Enabled" on both

Any time DC voltage is high enough to enable grid support, the XWs always draw between 100 and 200 watts from the grid. It never sits at zero.
They don't seem to be able to independently regulate both phases of the output to independently reach "zero" on each leg. The result is perpetual mis-handling of export. This is a big deal since exporting without utility blessings can trigger some nasty-grams from code-enforcement.

Here are some screen shots depicting what I'm talking about:
1. despite my export being set to "0" and Sell disabled, that is apparently not enough to prevent actual export (AC L1 Current)
View attachment 125027

2. Grid current is NEVER zero. It's always taking 100-200 watts, but what's worse is that it often spikes to 700+ watts of export depending on loads:
View attachment 125028
3. Sell is set to disabled and Export current set to a maximum allowable amperage of 0.0, these number should never grow. but they always do:
View attachment 125029

Based on my understanding of the architecture of the XW's block-diagram and principles, I imagine only two possible solutions to the problem:
A. Run all loads through a 240-240/120 center tapped transformer
B. Take the XWs off-grid and use an external battery charger

Either option would be expensive in both cost and power efficiency. Anyone got a better trick up their sleeve?

Like I Have Said These Guys Are not the sharpest pencils in the box.
They need to have a Class action Law Suit to get their attention. I have spent over two weeks talking to their techs and get answers from them that make no sense and if what they are telling is true, their programmers and engineers need to go back to school.
Earlier this week they told me that you cannot use the Lithium Ion Battery selection with SOC because it doesn't work with Kilovault Hab 4 Batteries. Their answer to my problem of getting F75 on the Inverter was to switch to open loop mode, and select 2 stage and turn off SOC.
When all that was needed was to go to the Battery Management Systems Menu and Change the Over Voltage Offset to 3 Volts. My question is why do you need to have an over Voltage Offset at all; Unless you are patching an older system designed for Lead Acid Batteries? That's why it exists. The programmers should have written new code specific to Lithium batteries use, instead of patching old programming code.
Now these super techs are telling me the reason I can't sell to the grid is that the grid voltage on my 120/240 line is out of balance by 2.7 to 3 Volts between L1/L2. I hate to give them this revelation but: This is going to be a real problem for anyone connecting to the grid in every town in America. The way it works is that the Pole Transformers that take the voltage down from 35KV to 2.6 KV primary Voltage to home split phase 120/240 Volt are usually limited to 200 KVA or about 10 homes per transformer and these loads are never balanced because you will never know how the loads on those homes are distributed in the loads panels of all these 10 homes. So the Inverter has to match the Voltage Phase and Frequency. If you don't match you can't connect. That means the inverter has to be designed to match these parameters. Including Voltage it's ridiculous to think they would be so stupid to design a Grid Tie Inverter that can't connect to a Grid because it can't adjust the Grid Voltage. The Inverter already has functions that Qualify the Grid and displays the fact in the user interface. What a joke these so called Techs I would bet don't have any training with electrical engineering of any kind. These guys are only script chasers and know nothing about much of anything.
You can really tell that the the programmers are also whiz bang programmers. Just Look at the Way you have to turn on the ability to sell to the grid. Its not in the inverter parameters menu. Its in the Systems Set up Menu buried in another menu called Smart Energy Manager. Also They make it not intuitive. They State "Configure parameters to inhibit power export to the grid" So you have to Disable to Enable Grid Sell. "Idiots" That's My Opinion. As you can tell I am Not a fan of Schneider Electric's XW-pro. Don't get me wrong I like the fact that their products have a good reputation and its ability to power Inductive loads is impressive, but this New XW-pro has NOT been Run through the mill and Really Qualified. Stamped and Shoved Out the Door, Most Likely during the pandemic.
Has anyone you know actually set up a system with Kilovault Hab4 Batteries and connected to the grid and Sold Back Energy?
Please Post if you know of anyone.

 

[Allgood-Energy]

Some observations to report...
I enabled both XW Pros
Enabling both battery chargers in the two XW Pros resulted in an imbalance of state condition where one XW chargers goes into absorption mode but the other XW then pushes into AC1 to try to meet the criteria of the Grid Peak Load Shave criteria, which on both XWs is set to 0 amps. So, one of the XWs is working hard to convert DC into AC, and the other one is matching those efforts converting AC into DC, but all they're ultimately doing is making heat and noise in a pointless circle of catch-22 as the battery continues to hover just above LBCO. Since the aggregated metering of both AC1 inputs is used for grid control, it does still maintain the 100-200 load on the grid, and only momentarily goes backwards with load changes or excessive 120v load imbalance.
Disabling the charger on XW Pro 2 prevents the circle of self-gratification, apparently.
Ultimately, enabling Grid Peak Load Shave didn't result in any favorable changes in functionality.

It could be accomplished in firmware with this inverter architecture, but I have yet to find a way to achieve what I want with the current 1.11.01b49

What I would ask for is easy to describe:
- Full self-consumption and zero-sell
- inverters allowed create waveform, asynchronously is acceptable, or be synchronous as long as true 100.00% net-zero
- 3 definable time windows with different priorities for each timeframe setpoints
- Off-Grid unless batteries reach recharge setpoint (5% SOC for LiFEPO4 or 50% SOC for FLA) if during top tier TOU meter rate
- Off-Grid unless batteries reach recharge setpoint (10% SOC for LiFEPO4 or 55% SOC for FLA) if during middle tier TOU meter rate
- Off-Grid unless batteries reach recharge setpoint (15% SOC for LiFEPO4 or 60% SOC for FLA) if during lowest tier TOU meter rate
- when not charging, and immediately after charging complete, disconnect from grid, or maintain true 100% net-zero
- do not arbitrarily draw 100-200 watts when battery above LBCO - I want 0.00 watts

I'm not holding my breath for this dream to come true. In the mean time, I am making plans to augments my system with external battery chargers. This utterly sucks obviously because I lose all the cool metrics of power flow data. Frustrating.

View attachment 125297

My Guess as a Engineer is that the Load is always out of balance because you neighbors next door loads are out of balance, and anyone connected to your Pole Pig "Transformer"
all these homes are connected in parallel on that transformer. I Noticed My Inverter transformer start to hum loudly intermittently. I can only attribute this to my neighbors turning on and off loads and the Current on the low leg returning on the Neutral. and My Inverter transformer trying to balance the return current. This intermittent Hum even occurs when my system is in pass through and the inverter has no current. Crap Design, The transformer inside I bet is a Auto Transformer and Not a Full Primary and Secondary Transformer that would Isolate these problems. Of Course this saves them money for copper, not having a Primary.

 

[dougbert]

My Guess as a Engineer is that the Load is always out of balance because you neighbors next door loads are out of balance, and anyone connected to your Pole Pig "Transformer"
all these homes are connected in parallel on that transformer. I Noticed My Inverter transformer start to hum loudly intermittently. I can only attribute this to my neighbors turning on and off loads and the Current on the low leg returning on the Neutral. and My Inverter transformer trying to balance the return current. This intermittent Hum even occurs when my system is in pass through and the inverter has no current. Crap Design, The transformer inside I bet is a Auto Transformer and Not a Full Primary and Secondary Transformer that would Isolate these problems. Of Course this saves them money for copper, not having a Primary.

thank you

mine gets that hum now and then (this afternoon for example) and I pondered why, this explains it.

Just got it 5 or so weeks ago, and am learning how to operate it.

My prior inverter was a Xantrex SW+ 5.5kwh 120v that I used for 3 years I think.

still learning this one

 

[dougbert]

@Allgood-Energy

Got that hum again today and went and disconnect from the grid. Hum went away

later turned grid back on and Bypass started.
Shortly there after, hum returned and I got -23 amps on L1 and +3 amps on L2 showing on status.
Nothing in the house was pulling that.

I back flashed firmware to 1.11.00-BN28, after getting those weird grid surges OP mentioned - those surges went away there after

 

[pvdude]

I back flashed firmware to 1.11.00-BN28,

1.11.01bn49 greatly reduced the transformer(s) noise for mine!
Rural area here, 3 houses on the pole pig.

 

[dougbert]

1.11.01bn49 greatly reduced the transformer(s) noise for mine!
Rural area here, 3 houses on the pole pig.

that came with the unit, 400bird recommended the backward flash

this post shows the HUGE draws from the grid in rapid sequence, with the bn49 firmware

Solar house generator I started DIY back in 2000 - My path from Trace to Xantrex (on FLA battery) to XW Pro inverters on Tesla Model S batteries

thanks @jensenq been gone for 2 days for thanksgiving holiday. Got back and am experimenting with the interverter and charger to learn its operational behaviours house has been in a minimal power draw configuration while we were gone due to cloudy day today and yesterday, battery was at 45.6...

diysolarforum.com

btw, I just read your system configuration - sweet setup - thanks for the example

 

[400bird]

that came with the unit, 400bird recommended the backward flash

this post shows the HUGE draws from the grid in rapid sequence, with the bn49 firmware

Solar house generator I started DIY back in 2000 - My path from Trace to Xantrex (on FLA battery) to XW Pro inverters on Tesla Model S batteries

thanks @jensenq been gone for 2 days for thanksgiving holiday. Got back and am experimenting with the interverter and charger to learn its operational behaviours house has been in a minimal power draw configuration while we were gone due to cloudy day today and yesterday, battery was at 45.6...

diysolarforum.com

Now that you've got your set up figured out, feel free to try going to current software.
The intermittent loud hum mine was making was due to fill 6kw sell to grid for no reason. Going back one firmware version fixed it for me

 

[pvdude]

this post shows the HUGE draws from the grid in rapid sequence, with the bn49 firmware

I suspect the reason mine has not shown that issue w/ bn49: no sell back, all DC coupled here.

 

[dougbert]

I suspect the reason mine has not shown that issue w/ bn49: no sell back, all DC coupled here.

I am also all DC coupled
but am using sell back at 0.0 amps, to max out PV product AND have grid for back up
I need another 6k of PV production to get off grid during the winter
during the summer I am 100% off grid

 

[Allgood-Energy]

thank you

mine gets that hum now and then (this afternoon for example) and I pondered why, this explains it.

Just got it 5 or so weeks ago, and am learning how to operate it.

My prior inverter was a Xantrex SW+ 5.5kwh 120v that I used for 3 years I think.

still learning this one

I am also New to this Inverter, But have spent well over a month in the manuals and weeks on the phone with Schneider Electrics Techs. Some of the techs are pretty good and some not so. Having an electronics degree and BS in Computer Science and worked in the Automation Engineering industry for over 40 years, it was pretty hard to swallow some of the BS I was told while working to get my system up and working. Some of the Documentation in the Manuals and Installation Doc's are at best sketchy incomplete. The Tech's have a hard time answering direct questions like what happens when one voltage set point is set above another, they can't answer because it's not in their "if this, then, that trouble shooting tree", and they don't really know anything about how the electronics work. You would think that a Billion dollar company could hire qualified people, but this new world order that China created after the pandemic has created some serious problems for everyone.

 

[Allgood-Energy]

OK another week has gone by and I have figured out where the out of balance is coming from, its not my neighbors causing the imbalance it was my sump pump. It was turning on and off quite frequently, this is a unusually wet winter, we have been in a drought so long I had forgotten about the sump pump. Its a 3/4 HP and pulls 10.8 amps on just one leg, wired 120 Volt. I need to change it to a 240 Volt circuit to balance the loads, and save a little money. The current draw at 240 will be half, but the watts will be the same, might save just a little on the difference in the I²R losses. I hope this will help with that hum. Crazy thing is that the pump is on the grid side loads panel and on even on the critical loads panel side that the inverter supports. I guess you have to remember the inverter does supply current to the grid in sell mode and does support the grid side up to the 6400 watts rating depending on where you have the sell amps set. Although I have never seen the inverter display watts above 2.4 KW. The KW display never shows the KW when I notice the Loud hum only --- on the KW display. MMM don't understand that. I would expect the KW display to show the watts of the max sell. So if you have sell amps set to 13 Amps, I would expect the watts to show a KW above 3.1 KW as long as the PV watts are available. That would show the 13 Amps Sell or 240V X 13 Amps = 3120 watts, plus any loads watts on either side of the loads panels, Critical loads and Grid side. I would expect a display of the total loads watts and what the sell amps are to be combined in PV watts are available, but how do you know what the programmers really did, as far as I know its not documented in the manuals any where. I would hope that the number on the display would be the total watts output by the inverter. There is no way for the inverter to know how many of the excess watts are consumed in your grid side loads panel. So the dash board display only knows the the direction of watts going out above the watts consumed in the critical loads and the fact that if there is excess watts above that it will display watts going out to the AC1 loads connected, it doesn't tell you if you have any excess KW sent to the Grid, only the Net meter will tell you that. If anyone else has a take on how this sell amps and KW display might work chime in please.

 

[400bird]

OK another week has gone by and I have figured out where the out of balance is coming from, its not my neighbors causing the imbalance it was my sump pump. It was turning on and off quite frequently, this is a unusually wet winter, we have been in a drought so long I had forgotten about the sump pump. Its a 3/4 HP and pulls 10.8 amps on just one leg, wired 120 Volt.

Wow, I wouldn't have expected that. Good find.

If anyone else has a take on how this sell amps and KW display might work chime in please.

I feel like you might be overthinking it.
When the kW dot is illuminated, the display shows you how much power the XW is inverting right now.
When the amp dot is illuminated, the display shows you how many amps it is pushing into the battery right now.

 

[GXMnow]

With my XW-Pro and the 16 Enphase iQ7 inverters all pushing at 240 volts, it does make for some odd negative currents from time to time, but when you trace what is going on, the numbers are right.

While on grid, any imbalance between the two legs is always being handled by the utility grid transformer.

I don't know for sure if Schneider supports this, but, what if you configured the two XW-Pro inverters for 120V only operation with the jumper set. Have one drive on each leg. Then they could each zero just the one leg. Each leg would now be able to handle up to a 12,000 watt surge for 30 seconds. Loads on one leg would have basically no effect on the other leg. I know Schneider supports using the 120 volt only mode, when combining 3 units for 120/208 3 phase, but will it work like this in 120/240 split phase?

So far, my power meter does not seem to care at all about my up to 10 amps of imbalance. The worst imbalance we get is running the hair dryer and the toaster at the same time, as they are both on the same leg. I have an NEM 2.0 agreement, so I intentionally have mine biased to export a little power to ensure I am not buying any. I think my export power scheme works about as good as the Watt-Node could. I calculate the power needed back in the main panel, and tell the XW-Pro to sell (that watts + 20) / (L1 volts + L2 volts) = Sell amps x 1000 milliamps. At the moment, I am commanding it to sell 256 milliamps. But since the sun is still blasting on the Enphase AC coupled solar panels, I still have 500 watts going out to the grid. The XW-Pro is pulling just 39 watts from the battery bus, but the DC charge controller is supplying 270 watts, so the batteries are still net charging, but very slowly.

With the XW-Pro sitting idle, the Enphase iQ7's are powering everything in my house, and the extra 600 watts is going to grid right now. But since my loads are a little off balance, I have 4.7 amps going out 1 leg and 3.8 amps going out the other.

If you truly do not want to have an NEM agreement, I think the best bet is going to end up having the XW-Pro running in Load Shave only. But then set it to just 0.2 amps, or something like that. Now it will stay in bypass pass through mode even for up to maybe 300-400 watts before it will pull from the batteries to help power the loads. But then trying to make it also power loads back in the main panel is going to be a problem.

This is not a Schneider issue, it is plain physics. Once it is commanded to push power out the AC1 terminals, the XW-Pro can no longer tell if it is powering things in the main panel or exporting power to the grid. That is where the Watt-Node meter comes in, but it is not perfect or super fast. When the load in the system changes, there will be times when it either consumes or exports for a bit before it can adjust to cover the load change. Again, NOT A SCHNEIDER ISSUE. While it can make very quick adjustments to cover it's output side, the grid side is different. Think in terms of DC to make it easy. Run a 100 foot bare wire pair. Connect a car battery in the middle. Measure anywhere along that pair of 100 foot wires, you will see the battery voltage. Now connect a 12 volt battery charger at one end. The current will flow through half the wire length and then go into the battery. The voltage on the other side went up a little, but there is still no current there. But if you connect a few car headlights, you could reach a point where all of the charger current is being used by the lights, and the battery just stops charging. But now you turn up the charger to a higher current to keep charging the battery at just 2 amps. All good, right? But now you turn off a light bulb. The battery charge current jumps up a bit. The charger is still putting out what it was told to. Now you have to measure the current at the battery, and adjust the charger to get the desired current again. Any time there is a load change, this adjustment has to happen. If the load change is on the output side of the XW-Pro, it has current sensors and it can respond right away. But when the load change is back in the main panel, it has no idea that change happened. The Watt-Node will see it, but then it takes a few adjustment cycles to dial in the ideal current again. Make the change too fast, and it might over shoot and swing up and back a few times, make it too slow and it might take a full minute to zero out the grid power. My setup using my own PLC is able to get it zeroed in about 15 seconds from any moderate load change. A very big current change might take another 5 to 10 seconds for 25 or 30 seconds total. The default settings when using a Watt-Node is 30 seconds per adjustment to increase sell current, and 60 seconds to reduce sell current. Some other hybrid inverters that have the external CT's wired directly in to the control board might be able to adjust quicker, but for most people, the minute of sell or consumption just is not that big of a deal. These small spikes of current happen even without inverters.

If you are truly banned from any export in any way, then you will need to build in an offset towards consuming a bit of power to allow for the power shifts when loads change. I really do not see a way around that.

It is now after 4 pm here, so my system has shifted to using the batteries to cover all my load due to the high time of use rate. The XW-Pro is puling 100 watts from the batteries, but my small DC coupled system is still pushing 200 watts, so the batteries are still charging. The Enphase inverters are supplying the rest of the power the house needs. Solar is falling off fast though, the batteries will be discharging within the next 30 minutes.

 

[Noname142]

I recently opened a "bug report" or "feature request" with Schneider on this subject. For me, I'm using a wattnode to enable zero-sell. With an imbalanced load, there are occasions where one leg is leaking power back to the grid. I suggested they make it a configuarable option..

One configuration: Let it operate as it does (for those that need it)
Optional configuration, have it monitor both legs individually. The XW Pro can't fix the imblance, but what they can do is.. if *either* leg is leaking, stop producing as much power for export. Yes, you may draw from the grid a bit more than you'd like.. but it's a much better option than leaking back (which depending on jurisdiction, may be civil fines, or criminal charges)

I'd rather pay for say.. 500 watthours occasionally, than to pay the fees/fines, and getting now power in return.

 

[ChrisG]

So even with the wattnode, power is still leaking back to grid? I would rather pay for a several KW a day (if enough Solar) than deal with grid-tie agreement.

 

[Noname142]

So even with the wattnode, power is still leaking back to grid? I would rather pay for a several KW a day (if enough Solar) than deal with grid-tie agreement.

Well, I wasn't fully clear. With the wattnode, you can set a limit of how much can leak back, OR a minimum amount you always want to pull from the grid. So, IF you are ok with always pulling "at least X watts" from the grid, you can likely eliminate the leakage.

As an example, I have an air fryer, and a microwave on the same leg (different circuits, same leg)
If I happen to run both at the same time (unusual, but not impossible) I can have somewhere near 15-20 amps of imbalance from my normal loads. If I wanted to, I could set the minimum utility draw to be "-1800" (15a X 120v) and this would make it so that if the power draw from the grid was under 1800w, the inverter would curtail and produce "0w", above 1800w, it'd start producing and selling back to the main panel, but not to the grid.

My feature request above would allow the system to stop monitoring it as "the sum of both legs", and instead monitor that either leg is leaking. if so, curtail to the point where neither leg is pushing back to the grid. This would allow you to set something more like -300, and get much closer to "net zero" without leaking to the grid one one leg because you're pushing it too close.

 

[pvdude]

I'm going to try an experiment.
(Will take a few weeks to get the HW in place.)
Dispensing w/ all the 120v loads on the inverters, converting all to 240v.
Interested to see if there is any effect on the leakage back to grid.

 

[GXMnow]

I consistently have a fair bit of imbalance on my system. Right now it is showing 3.7 amps going out L2 while L1 is drawing in 3.3 amps. The So Cal Edison power meter shows less than 20 watts. And my hourly usage graphs from SCE also agree that it is averaging the 20 watts I am seeing locally. In my case, I have it exporting that 20 watts as I do have a net energy agreement, but it is just a value change to make it importing 20 watts instead. I doubt anyone is going to ever notice the tiny import export swings and they only bother to report the average total for the hour. Starting and stopping a motor could cause some current reversal from time to time, but the long term average is going to stay importing from the grid.

 

[400bird]

My loads are also pretty imbalanced. The grid load normally sits around 80-100 watts from the grid. As in, I'm constantly buying a little power.

Right now, the grid load is 1.7 amps on L1 and -1.6 on L2.

 

[Noname142]

I'm going to try an experiment.
(Will take a few weeks to get the HW in place.)
Dispensing w/ all the 120v loads on the inverters, converting all to 240v.
Interested to see if there is any effect on the leakage back to grid.

I suspect your results will be just like mine. 240v loads will be pretty evenly balanced, and thus.. the only time you would "leak" would be for a second or two after a large load stops, and the inverter scales down the output. That takes a moment.

The "real" leakage we're discussing comes from imbalanced loads caused by 120v loads. It's generally this 120v imbalance that will occasionally see 1 leg importing, and 1 leg exporting a handful of amps.