Adding Schneider XW Pro

[400bird]

Not that schedule, I'm on E1

Nevermind, I'm a lier and had to go check: E-TOU-C

 

[Hedges]

I'm not seeing any peak/off-peak in E1

https://www.pge.com/tariffs/assets/pdf/tariffbook/ELEC_SCHEDS_E-1.pdf

 

[400bird]

I'm going to have to watch this energy shifting, I might be best off to switch to the EV rate plan. But, there's a risk on hot days when the AC needs to run a lot, the battery won't get to charge enough to cover evening AC use.

 

[Hedges]

That may depend on which usage tier you hit now:

Baseline Usage $0.31465 (I)
101% - 400% of Baseline $0.39454 (I)
High Usage Over 400% of Baseline $0.49318 (I)

$0.24 isn't that much less than $0.31, but would be big savings compared to $0.49
$0.56 isn't that much more than $0.49

Would like a low-cost way to make ice off-peak and use it to cool house on-peak.
My first thought was a chest freezer full of water with an air duct through it. But power of compressor is low, and ice is reasonably good insulation.

 

[400bird]

I'm pretty sure I'd be on base line. I'll need some summer data to make sure that doesn't change. That seems more important than my current rate tier.

Here's the past week of grid usage.
It's spring, so best production and lowest energy use. You can see when 4 pm hits (or the battery hits full) and most of the PV is back feed to the grid at peak rates.



I'm pretty sure the chest freezer AC would get vetoed by the SO. To complex and ugly. She'd need to know how to adjust the temp...

We may do heat a heat pump mini split, multi zone. That's about as far as it could go.

 

[GXMnow]

I have So Cal Edison, and under NEM 2.0, I have no choice that is not "Time of Use".

So they have messed with the rates yet again. I think my pay off just dropped 2 years.

My current rate plan now includes $0.35 a day fixed charge. It used to be like 5 cents. So that is $10.50 a month, if I use no power at all.
Then they upped my off peak rate to 33 cents per KWH in Summer, and in Winter it is split to Off peak and Super Off peak 32 and 35 cents. So the cheapest is now 9 pm to 8 am, and goes up from 8 am to 4 pm, then the peak rate to 9 pm again. And the peak rate is differnt on the weekends now. 52 cents on weekdays, and 43 cents on weekends, in winter peak rate stays 46 cents.

The winter EV rate they offer here is a little bit cheaper off peak at 21 cents, but the peak is higher at 50 cents, and the fixed charges is now only $1.50 more per month at 40 cents a day $12 for the month. The summer rate has 2 levels, but different peak rate on the weekend again. 54 cents during the week and only 40 cents on the weekend. Off peak stays at 22 cents.

With the SCE rate comparison tool, they claim I would save $77 a year on the EV rate if my usage stays as it was for the last year. It has not. With the PLC controlling the battery charging, my usage has changed drastically. Since ALL of my consumption is only happening in off peak, I should save even more on the EV rate, since the fixed charge is only $1.50 more per month. At 11 cents less per KWH, I only have to consume 14 kilowatt hours in a month to cover that difference. But I have to really make sure I don't use any peak rate power. Actually, the peak rates are closer now. But I still don't want to use ANY.

but look at this math.....
My current cheapest rate is now 33 cents. My solar panels produce 8,000 KWHs a year. That's $2,640 a year in power I don't have to buy. And even the cheapest tiered rate is now 28 cents. Even that works out to $2,240 per year. my solar install cost me $12,000 out of pocket. My pay off is now under 5 years!!! Why doesn't every single house have solar panels?

 

[Hedges]

but look at this math.....
My current cheapest rate is now 33 cents. My solar panels produce 8,000 KWHs a year. That's $2,640 a year in power I don't have to buy. And even the cheapest tiered rate is now 28 cents. Even that works out to $2,240 per year. my solar install cost me $12,000 out of pocket. My pay off is now under 5 years!!! Why doesn't every single house have solar panels?

That works with net metering, or with batteries.

With net metering, rooftop PV has seen enough adoption to threaten the utilities. Future rate schedule will probably be credit 25% of retail, so you have to install 4x as much PV for any kWh you want to use later.

Your salvage batteries may look economical, but commercial batteries aren't.

 

[GXMnow]

My batteries, inverter, etc., added about $7,000 total to my cost. Yes, buying a packaged battery system is going to cost more. The server rack batteries alone come out to about $12,000 just for the batteries to match my capacity, an then you still need the inverter to handle them.

If I get 7 years out of my batteries, cycling 12 KWH each day, that would be 7 x 365 x 12 = 30,660 KWH cycled in and back out of the batteries. If it then costs me $12,000 to replace them, that is a cost of 39 cents per KWH cycled. About half way between my off peak and peak rates. So not really saving more than doing net metering. But at my actual cost for the batteries, I paid less than half that. And hopefully, I only need to replace the cells. My old bank BMS is even programmable to be able to use virtually any cells, and it will take up to 24S, so I could even do LTO cells, or 16S LFP cells. My second bank is using DUMB BMS units, so they are internally programmed for 14S NMC only. We will have to see what batteries are on the market in 7 to 10 years. If they die quicker than that, then I will need to rethink things. But cycling less than 50% per day, NMC seems to hold up quite well. The big one seems to be not pushing them over 90% charged.

 

[400bird]

Crazy day for production today. Went from a few hundred watts to hitting the programmed 5kw limit on the PV for 2 hours straight.

I only had to program in that 5kw limit to get through permitting because I couldn't convince the city that the XW wouldn't add another 27 amps on top of the 20 something from the PV. The compromise was to limit the PV in software. Now I'm sure the XW's export settings include PV (because it's on the load side in my set up) so I need to head out there and remove the PV limit.

I don't think I'll gain that much PV output, it only clips a few days of the year.

 

[400bird]

It's been a while since my last update.
I removed the PV software limit. The PV inverter will not artificially limit solar production to 5,000 watts. That said it typically maxes out at 5,300 watts when cool and sunny, so no big loss or gain.

It's been hot out for at least a couple days this summer which has given the the battery chiller a chance to shine.

Last summer in some limited testing the pack cell temps were over 100F, from memory it was 110f
Maybe I will run another test day without the chiller, but performance of the chiller has been excellent.

I currently have the chiller set to turn on at 34°c (93°F) and cool the highest cell down to 32°c

On hot days it will run once for 45-60 minutes when it is over 100f. This day was 103°f


We had a couple days over 105f and it had to run twice.
You can see the heat wave carried a lot of heat in the pack overnight. The morning started with the cells around 88°F
That definitely factored into running the AC twice that day. Likely more than the few degree ambient temp increase.



It was hot out for sure, the AC in the house ran at 2:00 am then again starting at 11:00am.




So hot and running the AC so much, the pack went 10 days without fully recharging.
The first couple days I ran the pack lower, then corrected to stop discharging the pack to support loads at 60% soc.
Every one of those flats on the bottom also included purchasing power from PGE. The pack normally made it through Peak rates, but no where near making it through the night.



It's looking like I need more PV. I bigger pack would help somewhat, but if I am not fully charging the pack, more solar is the solution.
I lost all my historical data due to me setting up the database compression incorrectly. I don't have any data from this last winter, but I expect I am short in the winter too.

 

[GXMnow]

Great Update

With my batteries hiding in my garage, I don't have your heat issue. They are up to about 86F (30C) now, with the outside air at 95F in the shade on my north side porch. My other outside air temp sensor is still out of the sun under the eve on the north side of the house. That one shows 102F because it is not far enough under the roof and it seem to be getting some radiated/conducted heat from the bottom of the roof overhang. Have you measure the real watt hours it takes to run the chiller?

I have thought about getting one of those heat pump water heaters. The cold side would chill my garage. But they cost so much more than a gas water heater, it would never pay off.

I am seeing the same trending on the crazy hot days. I have gone over a week without topping up my batteries. I let the 14 cell banks get down to 51 volts. That is 3.643 volts per cell. That works out to about 45% state of charge. On most of these hotter days, it was falling to that at around 11 pm to 3 am the next day. Then I run on grid until the sun comes up. Letting it run lower won't help because it is not getting the battery full. Yesterday was pretty hot, but I still had decent production. Th Enphase app reports that it produced 28.5 KWHs. The A/C came on twice while the sun was still up. It ran for just under an hour before I stop charging at 4 pm. At that point, the battery only got up to 55.72 volts. I let it charge to 56.98 (4.07 volts per cell). That last day it got up there was July 5th. It also maxed out on the 4th. On both of those days, it did make it through the night until the sun started charging again. So the amount I am allowing it to charge and discharge. seems to be good. I just need more solar to be able to get that much charge each day. July 6th was HOT! and the A/C ran for 4 hours, and the battery only made it back up to 54.7 volts. That managed to run the house to just after midnight. The house base load ran off grid power for 8 hours until the solar stated charging again. From June 17 to July 8th (My billing period starts on the 17th or 18th each month) I am still only using 2 KWH per day on average according to the SCE usage chart. So I "need" at least that much more production from solar. June 17th was my worst day so far. We used 18.95 KWH from SCE. Solar production was good that day, producing 28.5 KWHs. So to do that from solar, I would need another 19 KWHs of production. 19 + 28 = 47 KWHs total production. 28 / 4.8 = 5.83 sun hours. 47 / 5.83 = 8 KW of solar panel - 4.8 KW now = 3.2 KW of additional panels. Yeah, that's not going to happen. I am shooting for 2 KW of additional panels. That will cover most days.

But as far as battery capacity goes, it looks like the 36 KWH of battery is just about enough. That is the 4 strings of the Chevy Bolt packs, which is that same as you are running, right? Though, yours are all the newer ones which are a little more capacity. I can see that the new strings I got from you are consistently running 10% more current, on both discharge and charge. That means for the same voltage change, they are pushing 10% more watts. That is over 1.5 KWH more capacity on the new bank vs my older bank. My full cycle, all banks from 56.98 down to 51 volts is using just a bit over 15 KWHs. I am leaving about 14 usable KWHs in the batteries for an evening power failure, and to be nice to the batteries to help them last a good long time. Looking at the cell discharge graphs, that is running to just about 40% state of charge, and the top end is going to 90% state of charge. That means I am using up to 50% of the 36 KWH's, but I really don't. On days it hits full charge, I don't run out. And when I run out, it does not get fully charged the next day. I NEED MORE SOLAR PANELS.

 

[Hedges]

I NEED MORE SOLAR PANELS.

You're using Enphase, correct?
How badly over-paneled are they? How much PV capacity going to waste, in terms of kWh/day?

Perhaps there would be a better way to use them (different panels in a different configuration) and a GT PV inverter or DC SCC that would capture more from the panels you've got.

 

[GXMnow]

You're using Enphase, correct?
How badly over-paneled are they? How much PV capacity going to waste, in terms of kWh/day?

Perhaps there would be a better way to use them (different panels in a different configuration) and a GT PV inverter or DC SCC that would capture more from the panels you've got.

The Enphase inverters are grabbing more power from the panels than most system can. They come on very early in the morning and stay running out late. I am 25% over paneled, but that is only enough to make them clip when it is cool yet sunny in spring. In the hot summer days, it does get close to clip at solar noon, but there is still a tick of headroom. At best, a super efficient DC to DC MPPT charge controller might put 2 to 5% more total energy into the batteries, and then I still lose over half of the gain on the resulting total AC energy back out through the inverter. The night time power would be a little better, the day time power would be a little worse. It is nearly a wash.

DC solar panel rating in, to actual used AC power out is coming very close to the predicted solar insolation tables for my area. Today, I got 28.6 KWH of AC power from the panels. With 4.8 STC KW of panels, that is a solid 5.96 sun hours. In perfect conditions, with ideal panel angle, I could hit 7.1 sun hours of DC energy. I lose 3% through the inverters, and about 4-6% more loss from dirt and morning shading. And a bit more loss from the panels getting stupid hot. If the panels stayed cool, and I had no shading, I should be able to produce 33 KWH with the panels I have. I need more like 40 KWH to zero my power consumption in these hot months. That is the math I have use to come up with needed about 2,000 more watts of solar panel. Five 400 watt panels would be about perfect. It looks like the battery is just going to make it to midnight again. The A/C ran a bit over 3 hours again.

Just the outdoor A/C unit consumed 14 amps x 240 volts x 3 hours = 10.1 KWHs. The fan in the furnace, to circulate the cool air, took another 3 KWHs. If I make an awning of solar panels down the east side of my house, I think I could fit 4 x 400 watt panels, but they will only make power up to 1:30 pm or so, before my second floor totally shades them. But then I don't need the RSD or Arc Fault stuff. I also thought about making a sun shade on my back wall behind the house. I could put another 4 or 5 panels there. But that would need a long wire run back to the battery bank. I know the local electrical inspector would scream, but I could connect the output of a grid tie inverter to the feed going to the A/C unit. It has #8 wire back to the main panel. When the A/C is running, it would greatly reduce the power being drawn from the panel, and when the A/C shuts off, the back feed would only be 1,500 watts max, 6.25 amps. I know it is absolutely not allowed by electrical code, but there is no reason it would not be safe.

 

[Justeric]

My xw8548 has smoked these board. With code F55 and F01. Where could be the problem. The damage was extended to Daly Bms 16s 250amps. The charger is set to about 15% of its capacity. Pv 16pcs of 345w through conext mppt 60amp SCC.

 

[Justeric]

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.

This becomes a problem when the BMS cannot handle the 100amps pushed to it. My scenario it keeps switching of the bms. I had to adjust the percentage downwards

 

[GXMnow]

My xw8548 has smoked these board. With code F55 and F01. Where could be the problem. The damage was extended to Daly Bms 16s 250amps. The charger is set to about 15% of its capacity. Pv 16pcs of 345w through conext mppt 60amp SCC.

Fault F01 means the output voltage was too low. There could be several reasons for this.
The most common cause is an overload situation. The XW is not able to supply enough current.
Do you have the ability to still pull the battery summary for the time that the fault occurred?
What was the battery voltage and current at shortly before the fault?

Once the output FETs failed, it obviously could not longer put out enough power, but was it trying to do more than it's rating, or did it fail for some other reason first?

Fault F55 is an EEPROM memory error. EEPROM is a backup memory for settings. When any settings are changed, the live changes are done in RAM which needs power to hold the values. The XW line periodically writes the RAM settings values into EEPROM which is "Electronically Erasable Programmable Read Only Memory". It has to erase a group of cells, and then write the new values, and maybe some of the old values back to the whole group. The most common cause of the F55 fault is if the battery voltage drops too low while the system is in this process of writing to the EEPROM. Some of the cells may have been written bad values, or some cells may have been left erased. It knows the values are bad. It will load default values, and you may need to go into configuration to put your values back. The default values might be unsafe for some installations. For example, it may have set the charging current too high for your batteries.

When I had my BMS do a shut down, I was lucky it did not cause any other problems. Mine was not running at much current at the time. It was actually a bad cell voltage sense lead that caused the fault, so the BMS did not interrupt a high current. The XW just reported low DC voltage and went into grid bypass mode until I got the BMS working again. Had I been off grid, it would have been a much more serious issue. This is another reason I like having at least 2 battery banks. I now have 3 separate strings. So if a single BMS acts up again, the system can stay running on the other 2 strings.

 

[Hedges]

I am 25% over paneled, but that is only enough to make them clip when it is cool yet sunny in spring. In the hot summer days, it does get close to clip at solar noon, but there is still a tick of headroom.

OK, no opportunity there. It was the severe over-paneling due to undersized microinverters I was thinking of.

I figure SE and SW facing panels, paralleled and connected to an inverter which still isn't over-paneled, could deliver more kWh.
If at a steep angle to each other like 60 degree acute, then 300W || 300W = 300W but for more hours. Such an acute angle would reduce kWh/panel/day more than a 90 degree angle. Smaller footprint than all flat, but can't squeeze a large flat array (crinkling the surface into /\/\/\ panels) without them shading each other. Needs to be a long row of /\, or spread out /\....../\....../\, or / on one roof face, \ on other roof face.

Five 400W panels shouldn't be too hard to squeeze in. One row along the parapet of your garage roof?

How much improvement in efficiency of A/C might you get if still-hot discharge tube coming from outside condenser had a water jacket, further cooled by pool water or similar thermal mass?

You could take wire going to A/C, put it through a smaller breaker panel, one branch for A/C and one for GT PV inverter. If you want to prevent backfeed (current or wattage limits?) add a relay to connect/disconnect AC power of GT PV, controlled by AC power to A/C. Backfeed, if used, should comply with 120% rule and land at far end of main breaker.

 

[GXMnow]

This becomes a problem when the BMS cannot handle the 100amps pushed to it. My scenario it keeps switching of the bms. I had to adjust the percentage downwards

Even having the current dialed down is not good enough.
Schneider warns that under dynamic conditions, when running AC coupled, it will almost certainly have to pull nearly the full solar power and push it all into the battery as charge current. They warn in the AC coupling guide to ensure the battery bank is able to handle the full power of all installed AC coupled solar for this reason. These events are rare, and should only last a fraction of a second, but they can happen.

How much solar are you running? Are you grid tied or off grid? What cells are you using, and how many of them? What is their maximum C rate for charging? Using a single 100 amp BMS is a bit low for an XW inverter. My first single battery bank has a 200 amp BMS, with surge capability to 350 amps. The maximum DC current on your 8548 is 180 amps. And that can be charging or discharging. Even if you set the limit lower, it can spike up when the load change suddenly. It does correct very quickly, but it is not instant. Just last night, when my 6848 was running my home, my A/C compressor cycled off, and the LED lights had a very noticeable bump in brightness. The voltage surged up a bit before it was able to ramp the current down. It was a tiny fraction of a second, and most gear can handle it just fine. But if something causes the charge current to bump up like that, a BMS might react quick enough to trigger a shut off. And if it happens while charging, that can cause the DC bus voltage to jump vey high. That could very well cause other components to fail.

Under perfect sun conditions, my solar array can produce just under 4,000 watts. If my battery voltage was down to 48 volts, that would be up to 83 amps of charge current. Any one of my battery strings alone can take up to 120 amps, so I am good there. But if I do ever end up with just one of my new battery strings working, those Daly BMS units will only hold 100 amps of charge current for 30 seconds before they shut down. There are 2 strings like that. My old string is actually 2 parallel strings of the same cells. So that third string could take 240 amps, and that 200 amp BMS is set for 150 amps of charge current for 30 seconds before it would disconnect. My older high power BMS is a "Smart" unit with live readings and many adjustments. When I added the two new stings, I just went with a pair of dumb BMS units. Knowing what I know now, after 2 years of "learning" I might get 3 more smart BMS units, and make my system into 4 strings that I can monitor. The Daly dumb units look to be working just fine, but since I can't monitor them, all I know is the cells are charging and discharging. I have to use a meter to check cell voltages. Last time I did that, they were balanced within 0.010 volt from lowest to highest. I periodically also check the current in each battery string, even the two separate strings on the one old smart BMS, just to be sure they are sharing the current. I have never seen any string off by more than 5%. The maximum current I have run yet has just hit 107 amps total. No single string of cells was over 30 amps. Each string is 180 amp hours. So that is just 0.17 C rate on cells rated for 1C charge and 3C discharge.

After watching many threads here and watching a lot of videos, I don't think we should push any BMS to more than 50% of it's advertised ratings. It's not that the manufacturers lie about their capability, but in these high power situations, current surges and spikes do happen.

 

[GXMnow]

OK, no opportunity there. It was the severe over-paneling due to undersized microinverters I was thinking of.

I figure SE and SW facing panels, paralleled and connected to an inverter which still isn't over-paneled, could deliver more kWh.
If at a steep angle to each other like 60 degree acute, then 300W || 300W = 300W but for more hours. Such an acute angle would reduce kWh/panel/day more than a 90 degree angle. Smaller footprint than all flat, but can't squeeze a large flat array (crinkling the surface into /\/\/\ panels) without them shading each other. Needs to be a long row of /\, or spread out /\....../\....../\, or / on one roof face, \ on other roof face.

Five 400W panels shouldn't be too hard to squeeze in. One row along the parapet of your garage roof?

How much improvement in efficiency of A/C might you get if still-hot discharge tube coming from outside condenser had a water jacket, further cooled by pool water or similar thermal mass?

You could take wire going to A/C, put it through a smaller breaker panel, one branch for A/C and one for GT PV inverter. If you want to prevent backfeed (current or wattage limits?) add a relay to connect/disconnect AC power of GT PV, controlled by AC power to A/C. Backfeed, if used, should comply with 120% rule and land at far end of main breaker.

The ridge board of my roof is running east to west, with the south face turned about 20 degrees to the west. Putting panels on the other side of the roof would be facing mostly north, turned 20 degrees east. They would make good summer morning power, but then fall off very fast, and winter production would be horrible. Going straight flat horizontal is looking very good though, which is why I keep looking at my garage roof. The east side awning idea also look good for morning production, as it is actually turned 20 degrees to the south. Even in winter, that area would make very good morning production. When my batteries run down too low overnight, it is not a bad idea to have early sun to start charging them up.

Here is my production from yesterday.
You can see my peak output fell at about 1:30 PM. That is caused by the 20 degree turn to the west. The system hit 3,500 watts. That is about 220 watts from each of the 16 inverters. They are rated for 240 watts constant each. In cool sunny weather, they will max out the 240 watts for up to 2 hours. But with the temp coefficient of my 300 watt panels, it just does not happen when it is this hot out.

My breaker panel, Enphase gear, and the XW-Pro battery system are all on the east side of my house, near the south end. The best place to put ground mount panels is the complete opposite corner of my property. The A/C outdoor unit is in the middle of the west wall. If I do replace the safety disconnect with an outdoor rated sub panel, would it actually be legal to back feed solar into that sub panel? I know it is completely safe. No buss bar is going to be stressed with less than 10 amps of back feed. And most of the time the A/C is running, the current is being reduced. But "safe" and "legal" are not always the same thing. And I just can't bring myself to move the A/C load into my backup loads panel. So that brings up another issue. The breaker to the A/C could not go in the bottom slot of the breaker panel. The very bottom slot is the back feed breaker going to the XW and the backup loads panel with the Enphase which both can make back feed current.

The conduit run to the A/C unit is 3/4 inch. I could easily pull another pair of #10 wires in it, and have the solar back feed come back to the Enphase Envoy. But then it really defeats the purpose. Even if it is legal (I don't think it would be) I now have that added solar power going all the way across the house, and then back out all the way across again to feed the A/C compressor.

I am such a procrastinator. I just need to get the panels, and put them on the garage with more Enphase Micros. It is the best overall solution. My only problem ends up being the slight possibility of exceeding the 120% rule for backfeed power. If I line up 4 x 400 watt panels on iQ7+ microinverters, I could possibly produce a peak total solar power of 4,000 watts from the existing solar at inverter clipping + 1,475 watts from the 5 additional panels at 295 watts each at inverter clipping = 5,475 watts maximum. That would be 22.8 amps going back to my main panel if there was no loads in my home at all. I know my base load is always 800 watts. That drops it under 19 amps going back. I just need another 600 watts of dump load I can turn on if the battery bank becomes fully charged before solar noon. And only on a cool sunny day. Also, the 5 flat mounted panels on the garage will have their power peak about 90 minutes earlier than the existing array. That will also help a little.

 

[Hedges]

Having a branch circuit feed a sub-panel, which then feeds two loads (A/C and GT PV inverter) should be perfectly legal.
Obey 120% rule for that panel, and for the main panel that feeds it. Which includes breaker at far end of bus from main breaker. Many panels have two rows of breakers, so two dual breakers at far end would be in compliance.
Small panels without main breaker often have L1 and L2 fed from opposite ends of panel, so no way to do "far end" for 120% rule, therefore select panel to be within 100%. A 70A or 100A panel should do it, just need enough slots for 2-pole breakers.

Does your your PV go through a visible-blade disconnect? If so, additional PV inverter should too. Required when I installed, but utility later gave the option of no disconnect; they would yank meter and leave property without power if necessary to positively disconnect PV.