Adding storage to my Enphase system

[Ampster]

You may already know this but I saw a report on another forum that one of the issues with the LG Chem batteries in Bolts was that the charging voltage was to high.

 

[GXMnow]

I am trying to follow any news I se since I am using those batteries. And if it is true that they are just charging them too high, then I have no worries at all. I am stopping short at just 85% charge now.

 

[400bird]

How's progress on the controller code progress?
And no battery fires ?

I'm still having trouble with inverter choice...
Loving the specs and capacity on the schneider, just struggling to pull the trigger.

 

[GXMnow]

Honestly, I have not worked on the PLC code for about 2 weeks now. My work has actually had me do a few things. So the code is still in limbo. I am manually changing the settings twice a day to keep it time shifting my power.

Having the main house loads on the backup panel has altered the operation a bit. Even outside of the "Grid Support" window, it keeps going in to invert mode to help power the loads, right after it completes the charge cycle. And it still inverts to power loads after my time window as well. I am setting the "Recharge volts" so it has to cut off close to 9 pm, and that is sort of working. I will add that function in the PLC once I actually get it working. Of course, I did not realize it was running on invert even past midnight, and I have now run the battery bank lower than I ever intended. It pulled it down to 20% SoC without a problem, other than it took me 2 days of charging from the sun to get it back up. I could certainly have hit the charge harder, but did not want to use any grid power. Through all of that, the battery temp has still never gone more than 1 or 2 degrees above the surrounding air temp. Touching it, it feels the same temp as the concrete floor. During the power failure, I did see current spikes up to 80 amps when we ran the microwave oven, and that was with the fridge and furnace running and some lights on and a PC etc. So far the battery bank has been rock solid. The Schneider XW-Pro inverter is rock solid and working great. I just wish they could get the software to make it time shift power with AC coupling and grid tie operation. It works great off grid, or with DC charging, but on grid with only AC coupled solar, it has an issue. The inverter won't pull the battery bank down to where it will start another charge cycle.

Knowing what I know now, I am on the fence. The Sol-Ark does look great on paper, but after looking at the manual, it also does not seem to work well with only AC coupled solar. It really is meant to work with DC solar connected through it. The Outback Skybox looks to be the best package at this time, but it is just 5,000 watts and a bit expensive for what you get, but it works and has good support. The Schneider is a well built solid product, but the support is not great and the software has a few holes they need to fix. I truly believe a simple patch in the Gateway could cure the problems, but they are reluctant to even try. They want to sell an MPPT charge controller. I am opening a new service ticket about the issue with it inverting even when I have grid support disabled. Let's see where this one goes. I hope to dig back into the PLC soon. I know that will make it work, but my coding skill is so rusty. I know I can make it work, but I am really trying to make the code modular and efficient. If I just hard code it, it will be tied up doing nothing but my functions to my ip address etc. It will make it a pain for another user to put on their system.

 

[Ampster]

The Outback Skybox looks to be the best package at this time, but it is just 5,000 watts and a bit expensive for what you get, but it works and has good support.

The Skybox inverter capacity is 5kW but AC coupling can add 7 to 9 kWs. The total throughput is 14kW limited by 60Amp breaker and AC coupling dynamics.

 

[GXMnow]

With my current arrangement, the Skybox would provide enough power. It is rare for me to exceed 4,000 watts. Due to how the power is distributed though, I now have my main garage circuit on the inverter output. That put my air compressor on the backup circuit. I need to remember to shut off the compressor if I have a power failure. It is rated at a very optimistic 3 HP but it is actually more like a real 2 hp. It draws 16 amps on a 120 volt outlet now, I want to rewire it for 8 amps at 240 volt, but in either case, it is just under 2,000 watts while it is running. My son was working on a friends car yesterday, and it had to cycle on 3 times. Each time it kicked on, the battery current went to 52 amps going into the inverter. That is pushing about 2,860 watts with the other loads on the inverter. So even then I still have some room to go. Add in the microwave 1,600 watts and it is still not a problem. But I do need to at least add a separate outlet for the welder. Before I moved the garage to the inverter backup panel, I had to be sure the air compressor did not start when I was welding. My small Hobart MIG pulls a solid 16 amps at 120 as well. I had always planned on dedicated outlets for the compressor and welder, but just never got around to putting them in. I want to et a TIG welder, and that will need a 20 amp 240 volt outlet. Since I have now removed 4 circuits from the main panel, I have room for a pair of 240 volt feeds to power them. I just have to add a conduit across the length of the garage. The old garage feed is non metallic "Romex" type wiring. If it was a conduit, I could just pull in the extra pair of wires, but no luck there.

 

[Hedges]

I need to remember to shut off the compressor if I have a power failure.

Mine tended to come back on in the middle of the night when pressure leaked down enough.
I made a short extension cord (wired with 240V/20A plug and socket) with a spring-wound timer in series. That lasts through my car repair task and remembers to turn it off for me.

I also need to run some cat 5 around for load-shed of various load. I plan to get a couple knock-down panels for where the cables run from inverters and between buildings. Then I can do some relay logic for various loads, also power status lights since I don't notice power failures anymore.

 

[Maast]

Rather than a Skybox how about a Outback 8048 Radian that you can stack a 4048 with it bring you up to 12kw of inverter. It does AC coupling just fine but you will need to have some sort of 48v battery.

The way the Radians work is they use 4000w 240v split phase modules internally and then stack them. As it needs more power it turns on more modules but when the demand is gone it turns them back off leaving just a 4kw module running meeting your base loads. Very energy efficient and not burning power keeping a entire 12kw of inverter on and working.

 

[GXMnow]

I did look into the Radian. It is an older design but it does have a decent track record. In a direct comparison to the Schneider XW-Pro that I did get, it was pretty close. The single module 4000 watt was not quite up to handling my 16 Enphase microinverters in AC coupling, so I would need to go to the 2 module 8000 watt, and then the cost was a bit more with no real benefit that I could tell from online research. And then the use of just spring loaded clips for the grid and load wire connections made me nervous. The screw down clamps in the Schneider just seem so much more secure. The required extra support gear was also similar, but the Schneider again seems a little more polished with the new Gateway. But now in hindsight, maybe the Outback would do the energy time shifting without needing intervention?? The Schneider hardware is very well built and it handles the power without any concern. My only complaints are the software limitations and their tech support.

 

[400bird]

Yeah, I also couldn't do the Radian 4048 and the 8048 quickly gets pricy when I need a control panel and distribution/fuse panel. The Radian ends up roughly $1000 more as I need to build the system.

I hate to continue to hijack your thread, GXMNow.

But, I'm thinking of going with the XW pro with a standard install.
Then, after it passes inspection, do like Schneider suggested and install a relay to disconnect from the grid and force the XW to recharge from solar.

This will allow the system to function roughly how I want it until I (you, lol) figure out the controller to force the XW to act as it should.

 

[GXMnow]

My simple fix idea is a bit different. I am thinking of just adding a 2,000 watt charger that will turn on from a timer while the sun is shining. The XW will just stay in either standby pass through or grid support modes and never have to charge. The charger will get it's power from the solar as long as it is producing enough. If solar falls short, it will take from the grid. I'll make sure the timer will never trigger the charger while the XW is inverting, or if the grid is down.

 

[GXMnow]

I already posted in the Heltec BMS thread. About 15 minutes after my inverter started outputting power, the inverter shut off with a low battery warning. It turns out, my JK (Heltec) BMS shut down due to a cell voltage error. But when I checked the cells, they ae all fine and still near perfectly balanced, The BMS is reporting no voltage at all on cells 3 and 4 even though they measure fine even at the BMS connector.

I have done a bit of testing, and I can't find any obvious failed parts, but the BMS is not reading those 2 cells. I am going to try and contact the seller that I bought it from and see if they have any idea or a replacement option. It has been running fine for 255 days, so I am guessing they will not replace, but it is worth asking. I have tried a full reset on the board with no luck. I jumped out the BMS and the rest of my system is working fine. I will not leave it running without a BMS, so I need to get something ordered soon. The cells are measuring perfect on balance, so I will let it run a bit but only while I am home. And I will check it often.

I am a bit disappointed on the JK BMS. I know I talked it up a bit to others, hope they don't all fail like this. There was another on this forum who did mention a similar problem where it stopped reading 2 cells, so I feel bad there is a flaw. I am hoping I can find a failed resistor or something, but so far it all looks good.

 

[GXMnow]

It turns out the actual JK BMS board is fine. The problem is in the wiring harness that was supplied with it. The crimp terminal in the connector that plugs into the BMS is making a poor connection. I got it to connect again and it is working, but I need to repair or replace the pin. There may be more bad pins, so I plan to replace the entire harness.

 

[400bird]

Awesome news! Glad it was an *easy fix.

Easier than dealing with the vendor to warranty the BMS.

 

[GXMnow]

Tonight after 9 pm when the inverter shuts down, I will re-install the BMS system with my repaired balance lead harness. To test the leads, I powered a car tail light bulb through each lead and measure the voltage drop across the wire and connectors at both ends. All 16 wires drop between 60 and 65 millivolts under the load of the bulb. The bad lead was dropping nearly a full volt. It appears the crimp is on insulation and not the stripped wire. It only worked because it poked through and was grazing the wire inside. Just a tiny bit of corrosion and it stopped conducting. While the BMS was out, I added a new heat sink on the inside surface. I also added some thicker thermal pads as only half of the FET's were actually contacting the aluminum case for cooling. Now it has to squish the thermal conductive foam pad to fully close the case. The FET's were typically running about 3-5 degrees C warmer than the battery bank. Hopefully the better thermal connection will keep them a little cooler. Not that it was any problem at 30 amps, but if I load it up to the 140 amp limit of the inverter, it might make a big difference. I'll snap a few pics as I put it all back together.

One funny thing I noticed, even after a full factory reset on the BMS board, it still shows it has been running for 225 hours. The time counter did not reset. But it did clear out the amp hours cycled.

 

[GXMnow]

I finally got an email back today from Enphase. They did send a firmware update to my system on Feb. 10, 2021 that updated my iQ7 micros to image 520-00082-r01-v04.20.03

The email said "Through the firmware upgrade, we resolved the issue that stopped inverters for the day ( Jan 19, 2021) when there was a grid shut down."

I don't plan on doing a power fail test any time soon, but if we do have a power failure, I will make sure to log what happens.

 

[GXMnow]

I did not get my installed last night. By 9 pm it was already down to 50 F in my garage, and my fingers don't like connecting wires while shivering. I need to disconnect the main negative lead from the battery bank to put the BMS back in the circuit. Looks like we may have the cold front here for a few days. I am not worried about the battery bank, checked it again today and all the cells are still balanced within 6 millivolts. Today is very sunny, but still on the colder side. So my solar is doing great. Topped 3,700 watts before noon. My solar noon is not until 1 pm here. The Enphase inverters will clip out at 3,840 watts. Looking at Enphase installer toolkit at 12:19, it is now showing just over the rated 240 watts on all 16 inverters. 3,860 watts at the iQ combiner box. I just kicked up the charging current a bit as I am exporting quite a bit right now.

 

[GXMnow]

I have my JK BMS re-installed in the battery bank and wired to the cell monitoring leads. All I have left to do is re-connect the high current DC line back through the BMS. The cells showed as balanced within 0.007 volt when I powered up the BMS. I set the target down to 0.003 and let it run balance for a bit. It pulled them to within 0.003 in about an hour. I set it back to 0.006 as they only spec it to be within 0.005 anyways. Don't want it working to unbalance the cells. It is cold again tonight, but not as bad as the last 2 days. I did all of the low current wiring before it got below 55F so I was not shivering with my hand around the cell leads. I will shut down the battery current when I move the 2/0 cables to the BMS in an hour. It's down to 53F out now, the garage is a little better.

I really do not miss living north of Chicago at all. 53F is a heat wave up there. My brother in MN had a high of 15F today. No thanks. Here in So Cal we still hit 62F today. The inside of my garage has never gone below freezing, but if we keep getting these cold snap, I may have to add a small heater in the batter cabinet. NMC cells can be charged a little below freezing, but it can still shorten their life. I have the BMS set to stop charge at 0C (32 F) just to be safe.

 

[400bird]

I don't plan on doing a power fail test any time soon, but if we do have a power failure, I will make sure to log what happens.

I don't know how you can do that. I couldn't manage and I would be flipping the breaker at 4pm that same day.

BTW, I just (finally!) ordered my XW pro. I guess I'll have to start my own thread once I get it going.

 

[GXMnow]

The BMS is still working perfect after almost a full day and nearing the end of a charge/discharge cycle. All cells are showing balanced within 0.003 volts and the calculated resistances updated. All are pretty close now. They range from 0.131 ohm to 0.142 ohms. Cell 9 is the lowest and cell 3 is the highest. Before I redid the harness, it was reporting cell 3 at 0.313 ohms (well over double), and the lowest was 0.143 ohms. So I think I am going to use some dielectric grease in the JST connectors.

My problem with doing a power fail test is that I have so many computing devices up and running, that if the system glitches, I have a whole bunch of things to reboot. All of my networking gear is now on the output of the inverter, so it either works and I can monitor it, or it drops out and I can't connect to it. Last time during the real failure, I had to take my laptop out in the garage and hard wire into the system.

Hoe you found a decent deal on the XW-Pro. I dragged my feet for 2 months and lucked out when Real Good put it on sale and offered free shipping. I had to jump, it saved me over $600. And certainly start a build thread. I like to ramble here. Even if people are not talking, I see a lot of views following my progress. Who knows what small thing happened to me that might help someone else out. I watch other people's threads for pearls of wisdom all the time.