Adding storage to my Enphase system

[GXMnow]

I am still fairly new on the forum, tried to answer a few questions as I asked some, and have been talking about my plans and purchases. I figure this is the right place to talk about what I am doing and where it is going.

My existing system is a very typical Enphase setup. I have 2 arrays of 8 panels each. The panels are Sil Fab 300M 60 cell units with an iQ7 inverter on each one. All 16 inverters are combined in the attic and go to an Envoy iQ3 on the wall of my garage near the power meter. I am at the limit of a single run with the 16 inverters. I have space to add more, but my existing main breaker panel is only a 100 amp unit, which limits me to a 20 amp feed in from the solar power system.

The system has now been running for just over a year and has been performing great. My south facing roof is at 210 degrees, so I stretch the usable sun a little into the evening, and the tilt of the roof is about 20 degrees which give very good exposure with the peak power in spring and fall. The 300 watt panels were actually able to clip the inverters for over an hour in May, pushing over 3,840 watts into my breaker panel. My production averages over 25 KwH a day and topped out at almost 32 KwH with all 16 panels making close to 2 KwH each. That is well more than I expected to get out of 300 watt panels. That works out to 6.7 sun hours. In summer (now) the panels are running a bit hot and the sun is higher than my 20 degree tilt, so I am not quite topping out the panels and inverters like it was in spring. Today, each panel was close to 1.7 KwH of production, for 26.4 KwH total. That is still 5.5 sun hours. Peak power was down to 3,460 watts.

During sunny cool days, I am pushing over 10 KwH back on the grid only to buy most of it back at a much higher rate. Even in these hot summer days, I still push over 5KwH out and have to buy much more to run the A/C in the evening. I knew I wanted to do "Time of Use" shifting with storage at some point. I was waiting on the Enphase Ensamble system, and looking into their batteries, but I just could not accept the cost for the rated performance. And the fact I would have to pay the installer almost as much as I did for the original solar gear install. So a few months ago, I really started looking into other storage options. The Tesla Powerwall 2 was looking like a fair deal, but it came with more than a few strings, and few installers would work with my existing system, and my original installer, does not work with Tesla. And trying to get a Powerwall 2 for a DIY install is not going to happen here in So Cal.

I looked into a few other ideas, but for safety reasons, I narrowed it down pretty quickly to Outback, SMA, and Schneider. I looked at Growatt and Sol Ark also, but they didn't have all the features I wanted. The Outback Skybox almost won, and has had some great reviews, but looking over the manuals, I was not totally convinced. The "one box does it all" system sounds great, but in the end, I liked the flexibility of the Schneider a bit better. So today, I placed my order for a Schneider XW-Pro 6848 inverter with the Conext Gateway box. It went on sale for a good price and a free shipping offer, so I clicked go. I should have it here by this weekend.

I have already talked about my battery on a few other posts, but I will summarize it here. Our friends at Battery Hookup had a great deal a few weeks back, so I picked up 3 LG Chem battery modules from a Chevy Bolt. I got 2 of the 10S 3P and one of the 8S 3P. I only had to cut one buss bar to split the 8S into two 4S groups. Then wired each 10S with a 4S and then paralleled the two 14S groups. The end result is 14S 6P of LG 3.7 volt 60 amp hour NMC pouch cells. 51.8 volts at 360 amp hours total or 18,684 watt hours. I figure about 17 KwH useable, but I do not plan to run them below 30% or charge them above 90% unless I am in a power fail condition. That gives me about 11 KwH to use every day for "time of Use" shifting which should just about eliminate any extra solar going to the grid and doing all self consumption. I am using the JK BMS with active cell balancing and the Bluetooth App. I have the 200 amp version that will do up to 24 cells and 2 amps of balance current. These nearly new LG cells are testing very well balanced so far, but without the inverter charger, I have only been able to push and pull 10 amps into the pack. Once the inverter is up and running, I will be able to give the pack a real test.

For the initial setup, I will just do time based control and have it charge at 1 KW for 10 hours while the solar is producing, and then push back 2 KW into my home during the peak rate 5 hour window. I may add a "WattNode" later to have it do true "Zero Sell" and the Schneider "Batt Mon" to give it more acurate battery status for "State of Charge" control of the store and sell as well as more accurate control if I have to run off grid during an extended power failure. Without the Batt Mon, it only uses battery pack voltage. These Li NMC cells have such a flat discharge curve, it can barely tell between 75% and 50% state of charge without measuring the current going in and out of them. My BMS reports a very accurate SoC, but for now, the Schneider inverter can't get the data from the JK BMS. That may happen in the future as the BMS does have both a CAN port and RS485 port for wired communication. I may be able to program an Arduino to read the BMS and report the data as if it is a Schneider Batt Mon.

Since this is the "Show and Tell" area, I will post a few pictures.

I will add a few more soon. I do have a few pics of the array etc. And even a few of the panels going up that I took with my drone.

 

[dougbert]

nice

which features did the sol-ark not have?

looks like you know your system and are doing do diligence with your home work. again nice

 

[GXMnow]

If I was installing DC solar as well, the Sol-Ark does look very good. But for the only solar being my existing Enphase micro inverters, I ran into a bit of a dead end. I could not find any decent instructions or setup examples for a system with only AC coupled inverters. The only mention in the install manual shows them going to the grid tie input, and only with some DC coupled solar as well. This became my biggest issue that took the Sol Ark out of contention. I could not find any examples of an AC coupled only system, or any at all with Enphase, on a Sol-Ark. This did not make me comfortable doing this setup. I am not against experimenting and trying a new setup, but in this case, the cost involved and the fact I could not find any example system that used just AC coupling on a Sol Ark, was just too much risk for me. It sounds like it can work, but their manual and anything else I found online, all says to use the DC solar connection. Does it handle the frequency shift to limit the battery charging when off grid? I can't find that info online either. The unit does sound great and if I didn't already have the Enphase gear, it could be a game changer. Maybe there will be more application notes in the future, but right now, it did not seem to fit what I want. The Outback Skybox looked very good, but there just seems to be a lot more experience with the Schneider / Enphase solution. I have read some issues, but it is documented, and Schneider has updated their software to address them. Both Schneider and Enphase mention each other in their tech notes on AC coupling as well.

While It may be possible to use the Enphase micros on the output of the Sol-Ark, I am not ready to be the beta tester for it. The AC coupling on the Schneider XW-Pro is very well documented and has been well tested with the Enphase micro inverters. Their latest software also made some big improvements in the frequency shift control for better charging when off grid. The battery charging control also seems more flexible for me to setup how it handles my repurposed Chevy Bolt battery modules. The documentation and existing user base with experience online also made me more comfortable with the equipment.

The final decision against the Sol-Ark came down to the cost also. They talk up being a single box solution making for big cost savings. That may be true if you are using all of the features, but it sure did not work out that way for my setup. This also hurt the Skybox for me, with a higher price, and 5,000 watts instead of 6,800. Most places only were listing the Sol-Ark 12K which is a bit over kill for my needs. The few listings I found for the 8K were still asking close to $6,000. I ended up getting the Schneider XW-Pro and the gateway for under $4,000 after taxes and with free shipping.

If I do add some DC solar later, maybe it would have been a better deal gettign one of the al in one solutions, but I doubt I will go that route. If the grid here does end up getting far more unstable with wild fires, earthquakes, etc., I may add 4 panels, and a cheap charge controller to just make sure the batteries always have some charge, even if the inverter has to shut down. But with a stable grid, the Enphase micros are more efficient powering my home with the battery just time shifting some power and waiting for a power failure. The greater round trip loss on energy going through the battery is a small portion of my energy as I am typically using 2/3 of my production as it is generated. I will time shift about 1/3 of production. So the round trip 12% loss vs the 8% loss on the Sol Ark, which only applies when charging from DC solar, is not really a concern. I'll bet the AC coupled round trip loss is about the same.

For now, I am looking forward to my XW-Pro getting here in a few days. I already installed a plywood backer board and the essential loads panel, and ran the conduits from the main panel and the solar disconnect. I still need to identify a few of the existing breakers. I know which loads I want to move to the backup panel, but they were not well labeled, and a few breakers moved when the solar was installed, so the old marker on the plate is wrong. I may also have to go in the attic and split a few things. The feed for the bathroom lights also feeds 3/4 of the main floor outlets lights and ceiling fans. But then the garbage disposal and the dishwasher both have their own dedicated breakers. I guess they probably should not share a circuit as the are rated at 9.3 amps and 12 amps respectively. Not that I would be using the disposal while the dishwasher is running.

 

[GVSolar]

Looks like a well thought out solution. Just a note: I have been using the Schneider Conext SW4024/MPPT 60-150 CC's in a DC coupled off-grid installation for almost 4 years. About 6 months ago I added AC coupled Enphase M215s. All work together seamlessly. One advantage of having the DC coupling along with the AC couple is the ability of the CC's to ramp up or down smoothly to even out frequency shifting - especially when batteries are approaching a fully charged state. Not an issue when you have the grid as a dump load, but something to think about in an outage scenario. I have the Combox/SCP and really appreciate the programming interface and graphing capabilities. Went to LFP from FLA this year. Best.

 

[GXMnow]

Here are a pics of the solar panel arrays



Not the best shots as it was pretty windy trying to keep the drone stable. You can see me with the remote in the back yard. You can also see the shadow of the drone on the roof.

The large area next to the lower array is due to keeping it out of the shadow of the upper floor in the morning. I had only planned on 4KW of solar anyways, so it worked out just fine with plenty of room for the required walk space next to the array. If I do add more panels, I was thinking of 4 at a flatter angle on the flat garage roof. The summer sun here is higher than my panel angle.



The existing solar install is very clean. The guys did a great job. The number of red warning stickers is a bit crazy, but that is our local code here.

All of the wiring to get up to the panels was run inside. The pic of the plywood backer is directly inside the garage behind the outdoor pics. The conduit on the left side is the feed from the solar panels. It is the one that is going into the side of the Enphase combiner box. It goes across the garage into the lower roof attic and then to the upper attic through the same passage as the A/C duct work for the second floor. There is a box in the lower attic where the two arrays combine. I may end up pulling 2 more wires and bringing them as separate feeds, as I am at the 16 iQ7 limit for a single feeder. It is safe and legal, but two 10 amp feeds on #10 wire will have a little less loss.

The sloppy flex conduit on the other side of the wood is the power feed to the A/C compressor. That was here when I bought the house, I may re do it in actual conduit across the garage. The essential loads breaker box is directly behind the outdoor solar disconnect shutoff switch and is connected to it with a 3/4 inch pipe now. This will probably become the disconnect between the new inverter and the main breaker panel. I may need to add another switch to shut down the battery bank and inverter. I have to verify the code on that. My original goal was to have the outside gear look unchanged with the added battery inverter, but that might not meet all the legal codes. As I have the wiring planned now, the disconnect will separate the inverter from the main panel, but the inverter will still be back feeding the solar combiner and the essential loads. At the very least, I need to have a switch out there to shut down the battery inverter. I will also add a small LED lamp that shows when the system is live.

The other box on the plywood is similarly connected with a 3/4 pipe to the existing breaker panel behind it. The existing wires for my essential loads should reach into that box, but will then need a splice to reach to the new breaker panel. I didn't put the breaker box there, as I did not want the splices to just add 5 inches of wire to make it to the breaker. This will look much cleaner when done. I have sen some pretty sloppy generator backup switch panels, with a lot of splices inside the breaker panel, and I wanted to avoid that mess. I also have to check if there are any issues with having my 4 backup circuits going through the existing panel. The only way to avoid it would be to open the wall above the old breaker box and cut the conduits and add a junction box up there. I hope I don't need to do that. I may slip some metal flex conduit over the backup wires so they are fully isolated from the other wires in the old main breaker panel. All 4 circuits I plan to backup go out the top and my pass through to the garage is near the bottom. There was no way I could punch another hole out the back any higher up, I had to go below all the existing breakers.

My battery bank is still in just an open rack. I will move it to an enclosed sever style rack cabinet after it is all tested with the full load so I can verify I don't have any issue with the BMS or other connections when I get up over 100 amps. The cabinet I found is pretty nice, but it does not have good access around the battery pack for checking the temps and voltage drop at all of the connections.



When it is moved into the final cabinet it will have better support braces, and I will clean up the wiring a bit more. The balancer leads are all the same length and fused, which added a bit to the rat's nest. I stuffed most of it between the packs, and notched the buss bar covers so I could have them on with the leads poking out. I am a bit nervous about my connections at the middle of the top 8S pack. The original buss bar looks like it is copper, or at least has a copper plating. My clamp is aluminum, but all of the current is carried by a copper plate that is directly clamped against the copper buss bar. In testing at 10 amps, my connection actually measures less loss than the original factory output buss bars from the cell tab to the stud. The two battery temp sensors are still just laying on top of the battery pack. Once I test at full power, I will try to find the hottest parts of the pack and I will use a thermally conductive glue to attach the temp sensors there. In my 14S 6P configuration, these cells should be able to take 360 amps all day long without a problem. The charger maxes out at 140 amps which is less than 0.5C, and while inverting, the maximum peak of 12,000 watts at 85% efficiency at just 48 volts would be about 294 amps. I have the two 3P banks fused at 125 amps each with a Blue Sea MBRF fuse block. There is a third fuse if I add another bank of cells or a solar charge controller. I plan to add a 200 amp Class T fuse at the inverter.



The two #7 awg wires going in and out of the BMS does concern me a bit. It is high temp fine strand silicon wire, but rating it for 200 amps still seems a bit dubious. The two banks of 3P are wired with #2 cable, and after they are combined, I am running 2/0 cable. You can see the short peices of the 2/0 up the the shut off switch and from the BMS to the negative buss bar. I need to get another black base to make it less confusing. My run up to the inverter will be only about 8 feet total. I am probably going to cut off the extra balancer leads, I will never go more than 14S. That bundle of extra leads is probably the biggest mess on the battery bank.

I will add more pics as the install progresses. If all goes well, I should be time of use shifting in about a week.

 

[GXMnow]

Looks like a well thought out solution. Just a note: I have been using the Schneider Conext SW4024/MPPT 60-150 CC's in a DC coupled off-grid installation for almost 4 years. About 6 months ago I added AC coupled Enphase M215s. All work together seamlessly. One advantage of having the DC coupling along with the AC couple is the ability of the CC's to ramp up or down smoothly to even out frequency shifting - especially when batteries are approaching a fully charged state. Not an issue when you have the grid as a dump load, but something to think about in an outage scenario. I have the Combox/SCP and really appreciate the programming interface and graphing capabilities. Went to LFP from FLA this year. Best.

Sounds like a nice setup. I did look at the SW's. A 4448 is about enough power, and would have saved a chunk of money, but with the amount of energy I may be able to time shift in Spring/Fall, I wanted to be able to grid sell some power at the highest time of use rate, so that took me out of the SW range. I have seen many great setup with the SW and it was one of my first options when I started looking into adding batteries. The only reason it can't grid sell is that they didn't go through all the UL approval for it. That would certainly add cost. I can see why they left it to the XW line.

With your Enphase M215's, I don't think they can smoothly taper power with frequency shift. They will probably just shut off at some point. So I can certainly see where having the DC charge will be a big help. I have iQ7's and I have them set in the rule 21 mode with the frequency watt function turned on. My original installer had left them set to "Default UL 1740" which I don't think is even legal here in So Cal. After the system is all up and running, I will do a light load off grid test and closely monitor how it functions as the batteries top out.

My bigger concern is if it does run the batteries down to "Low Batt Cut Off". If that happens, I will probably have to kick start the system with the generator. My old generator can't be made to use auto start, so I have to plug it in and yank the cord. I did just put a new carb. on it, and it starts in one pull now. I think I have enough battery for my truly essential loads. So when I know I am running off grid, I will be more frugal and watch my state of charge. It will be the surprise late night outage after I grid sold 2/3's of my battery power that could put my battery down too low.

I am looking forward to getting my Schneider inverter. The XW-Pro is not compatible with the Combox, so I am getting the new Gateway instead. The user interface looks very good. I hope it is as nice in reality. I didn't get an SCP at this point. I think I can do all I need to with just the Gateway. I always have a PC powered up on my network, so I didn't see a need for an additional control panel. The only bad thing I heard is if a firmware update goes bad, I might need the conext configuration tool to recover the system where the Combox was able to do it before.

 

[GVSolar]

The SCP can be VERY handy if/when your router/internet connection fails. Which it will, eventually. Whether or not that happens when you want to adjust a setting or check status is another question altogether. It certainly has happened to me, and at that point I was grateful for the xanbus connection and the buttons on the SCP. Best.

 

[GXMnow]

From what I have read on the Conext Gateway, You can log into it local without an internet connection. It will even act as it's own WiFi hot spot during config. It looks like it has a lot of improvements over the ComBox. I can always add the SCP later if it is an issue. I am also debating on the Battery monitor and a WattNode. That is one of the things I liked about the Schneider system, you just buy the modules you need and can add on at any time. The All in One is good if you use it all, but it is also a single item to fail.

 

[GVSolar]

I did not realize that... must work on xanbus only like the combox/scp combination. For some reason I thought it needed a network connection... my mistake. And yes, the single point of failure on an all-in-one can sometimes be an all-points-of-failure. I like being able to mix and match to keep up with any expansion - and new technologies. But I also like Schneider's tight system integration; it keeps my homework assignments to a minimum. Best.

 

[GXMnow]

I got the call from the shipper earlier today. My Schneider XW-Pro, conduit box, and Gateway will be here Tuesday afternoon (12 to 5, nice window)

Once I have them here, I be able to talk a lot more about the connection and setup. I am going to spend some time tomorrow morning making a bit more room in the install area so I can get a few good pictures as I get it mounted up and wired. At first I am just going to get the batteries connected and the input side to the grid so I can go through the config without taking any of my home down. We have at least another week of 100 plus temps so I am not excited about trying to pull all the backup loads through to the new panel in this heat. The door to the outdoor breaker panel was so hot I got a minor burn on my arm just holding it open for a couple minutes. The sun is shining on it for a few hours in the morning up to noon. Good thing the Enphase Envoy is shiny white plastic, it still gets warm, but nothing like that brown painted metal break box door.

 

[ArthurEld]

Thanks for documenting your experience GXMnow. I have been planning to put solar on my house for a long time.
I want to install a new grid tied system with either some or all panels using micro inverters. I'd like to use batteries for uninterrupted power and to withstand outages.
Like you said, the part in the Sol-Ark manual about using some micro inverters didn't seem comforting. They want you to use a certain percentage of micro inverters. And plug the micro inverters in were the generator would plug in. That sounds like some kind of hack. You have to wonder how efficient that would be. I think Outback might recommend plugging micro inverters in where something else would normally go. I am not very experienced with electrical but these kind of instructions don't sit well with me.
I read some people just plug solar into any outlet and it works.
Using an all in one box seems easier to grasp for someone with less experience like myself.
But I see I still have a lot of research to do before ordering my system.

 

[GXMnow]

This heat wave is a killer. It is making my A/C run nearly constant and the solar production is down a chunk. Here are a couple screen shots of my solar production and my SCE power usage for a couple days ago. SCE is a few days behind on their reports, so I don't have the last two crazy hot days yet.

Aug 16 production from Enphase, Not sure what time of day the temp is from, It was up to 100 that day, 86 was like 11 PM.

Aug 16 Usage from SCE

The Enphase is in 15 minute slices, the SCE is 1 hour, but you can see how they line up. On this hot day, I did not export any power to the grid. At 11 AM, I almost hit grid zero. If this kept up, I would not really charge my battery at all. So no power to export, even though the panels made a respectable 23.8 KwH. But thanks to cranking the A/C all day, I still had to buy 35.85 more KwH from SCE. So I used 59.65 KwH in my home, Wow, that is a lot of power. I think my son may have also worked on his car and the air compressor and welder may have run a bit too. I'll have to check if that was the case. A week earlier, it was only in the 80's and we were able to open windows at night as it went into the high 60's to help cool things off.

Here is the Aug 11 production, Again, 66 seems very cool, must have been at end of day.

The cooler conditions helped make 26.4 KwH's
And here is the usage from SCE for the same Aug 11

Here the house didn't get too hot until after noon, so I exported for 4 hours before the A/C started cycling. Funny how it looks like it ran an hour on, and an hour off, but it was probably quicker than that, with just more on time on the odd hours. It still got into the 90's with the A/C running off an on for 9 hours of the day.

On that day the total energy used in the house was 49.6 KwH's which is still more than I would have expected, but 10 KwH's less than this week. here is back from June. I tried to go back to further, but the SCE site is not letting me pull up that data.

June 16 production, we had some clouds move through, but the better sun angle and cooler air sure helps.

27.9 KwH's, and you can see the day before with less clouds it made 29.5 KwH's, 62 is still a night temp. Probably touched 80 that day

And without needing near as much from the A/C to keep cool, here is the usage

I was exporting over 2 kw at 11AM, looks like A/C came on and we had the clouds around 2PM. But then I was still exporting for 2 hours into the peak rate time. I guess we needed some more A/C at 7 PM. Total power used in the house was 35.47 KwH's. Not too bad. Only had to buy 7.57 KWH total from SCE. If I shifted the over production to the evening, I would have to buy a little more due to storage losses, but I would then only buy 15 or 20 cent power, and not buy the 40 cent power. On that day I exported a total of 8.59 KwH's during the cheap rate time. Exported another 1.33 KwH in the peak rate, but then had to buy 4.43 KwH's of peak rate power. I could legally store 8 KwH's and add that to the peak time export, even at 85% efficiency, that would be pushing out 6.8 KwH's more during the peak rate, so not buying any of the expensive power. And they would have to pay me a bit during that time. just like Covid-19, I want to flatten that curve. Get my SCE usage chart as close to zero for as much of the day as possible.

I am documenting this so I can see the difference once the battery is online in a few more days. We have at least another week of 100F weather, so I should get a decent comparison if the install goes smooth. If I can make it respond to the A/C load, I may even be able to get the cycling down. Hopefully we will see by next week.

 

[GXMnow]

Thanks for documenting your experience GXMnow. I have been planning to put solar on my house for a long time.
I want to install a new grid tied system with either some or all panels using micro inverters. I'd like to use batteries for uninterrupted power and to withstand outages.
Like you said, the part in the Sol-Ark manual about using some micro inverters didn't seem comforting. They want you to use a certain percentage of micro inverters. And plug the micro inverters in were the generator would plug in. That sounds like some kind of hack. You have to wonder how efficient that would be. I think Outback might recommend plugging micro inverters in where something else would normally go. I am not very experienced with electrical but these kind of instructions don't sit well with me.
I read some people just plug solar into any outlet and it works.
Using an all in one box seems easier to grasp for someone with less experience like myself.
But I see I still have a lot of research to do before ordering my system.

For "Grid Tie" power, it is just hard to beat all the advantages of the Enphase setup. Especially with the "Rapid Shutdown" requirements, it really does not cost that much more than a string inverter now. But when you want to have batteries as well, it throws a wrench into the whole equation.

When I ordered my system back in May 2019, there was only basic info about the upcoming Enphase Ensemble battery system, and I had hoped it would be what I was expecting. It is an excellent system, and I think it has some great potential, but the actual installed cost is quite a bit more than I was hoping, and from "svetz" experience so far, it seems the peak current from the batteries is not quite hitting the mark. He has had several software updates and the system is working better. He is documenting his system very well on the thread "An Enphase Ensemble Installation". If I had bought new batteries, I would probably be close to the cost of the Enphase batteries. My biggest savings is I am installing the new inverter. The two contractors here who would install the new Empower batteries wanted WAY too much. I almost went with a Tesla Powerwall 2. It is about the best bang for the buck for a complete new storage system, but I ran into issue with wait times, and the certified installers did not want to work with someone else's existing solar install. And good luck buying one to install yourself.

After all the study I did, the Schneider XW hit most of the buttons. When they updated it to the "Pro" version, it greatly improved how it would work with Lithium batteries and Enphase micro inverters. And the programming options make it incredibly flexible for how it will manage my energy. It also has a hug 12,000 watt surge power, so I know it will start anything in my home. Then add in the great deal I was able to get on the surplus Chevy Bolt batteries and my out of pocket cost is quite good.

On the negative side, there are a few things that I do not have yet. The Schneider system is very modular. But that means you "buy" each module. Since I am starting with my existing Enphase micros, I will not have an MPPT solar controller. This is not an issue now, but I may add some DC couples panels to help charge the batteries. The Schneider MPPT units that link to the Xanbus data network are pretty expensive, at about $500 for the cheaper 60 amp 150 volt unit. And I also want to have the output track my current consumption to limit export to the grid while still powering the part of my home that is still in the main panel, but in it's standard form, it only measures the current in and out of the XW box. This can do "grid zero" for the loads in the backup essential loads panel, but not the load in the main panel. Since I have some major loads back in my main panel, it will not know how much power to send back out the input side without another 3rd party box with external current measurement CT's at my breaker panel. That adds another $600 or so. Since it is modular, I can add it later, and I probably will, but for now, I can tell it how many amps to export, but it won't dynamically adjust as loads change. Since I do have a net metering agreement, I am ok with it pushing up to 16 amps out of my house without being in violation, so this is fine, but not ideal. Once I add the "Watt Node" CT box, It can adjust every few second, so if my A/C kicks on during peak energy time, it can send stored battery power back to the main panel to run the A/C and still have zero power coming in or out from the grid, and when the A/C stops again, it will go back to charging the batteries from the solar power, leaving enough solar to still run my minor loads. The Outback Skybox has both an MPPT controller and the external CT inputs included. I almost went to it, and "Ampster" is using one with excellent results. He has some Enphase and Solar Edge both feeding into it. His latest thread on it is "AC coupling my Outback Skybox to a Solaredge inverter". Our systems are a bit different, but we are trying to do the same thing. The main plan is to store power when the solar makes more than we need, and then use that power when the sun goes down. With the basic control built into the Schneider XW-Pro, I hope to reduce what I export now to near zero, and run my house off the batteries for just the 5 hour slot where my utility SCE kicks the rate to $0.40 per KwH and then run on the $0.25 per KwH overnight so I have at least 40% of my battery left in case we have a power failure. I miss my old tiered rate plan when tier 1 was just $0.15, but now I make some of my own power, so SCE wants me to pay MORE!

We don't have many power failures here now, but I expect it is going to get worse. We had one 2 years ago that lasted 3 days when an underground cable failed. And with wild fires and earthquakes, it could get very bad. We have had quite a few glitches during the "Lake Fire", and only a few blocks away, a whole area went dead, cutting power to 300 homes for 2 days. The fire is still burning. Having the batteries will reduce the cost of power a bit with the "Time of Use" rates, but it really won't pay off the cost of the gear, so it is the backup power that makes it viable now. Grid Tie solar is the most efficient way to make sun into AC power, but if the grid goes down, it has to shut down as well. Once you have to shuffle power in and out of batteries, you lose some of the energy. Combining the Enphase micros and an AC coupled battery inverter/charger looks like a very good compromise. If I can get the system balanced well, the only energy I will shuffle on a daily basis with the grid up is just the extra solar that I am basically giving back to SCE for free now. They only pay a net $0.02 to $0.06 for extra pushed back on the grid, and charge up to $0.40 when I need to buy it back as the sun goes down. If I can store 8 KwH that I am now sending back to SCE and then use it during peak time could save me about $3.00 a day. That does not sound big until you do it 250 days of the year, and I could save $750. Being more realistic, I expect to save about $1.00 per day on average, which is decent. Even if it never pays for the batteries, I am still giving SCE less money, and I will have power during a blackout. I have seen my system push over 10 KwH back in Spring and Fall, but with my A/C cranking I sent none back 3 days ago. It all depends on how much sun the panels see, and how much power you actually use.

Under the current California rules, it is not legal to sell back power that you charged from the grid, you can only sell power that the solar panels made. This prevents people from storing a ton of power at $0.15 on the EV owner "Prime" rate, and selling it back during the peak $0.41 rate. But if you can show your solar panels made more than you sell them, it is still legal. in an AC coupled system like I will have with the Schneider and Enphase setup, it is impossible to know which electrons actually went into the battery. But I can easily show that my panels did produce 20-30 KwHs in a day on their report page, so as long as my export is well below the production, I am legal, and they can't say I am cheating. In a perfect world, I would export nothing, and use all my own power. It would be great to only export when the battery reaches full charge, with all my loads being powered, and I have no where else to send the extra power coming in from the panels. This probably won't happen often, but if it does, it means I need a bigger battery. The other issue is getting the XW to adjust it's charge/discharge to exactly follow my generation and usage. Without the WattNode installed, I know for sure it will over and under shoot quite a bit. But as long as I stay within my NEM agreement of less than 16 amps of export current and no more than 900 KwH's a month to the grid, I am legal. But the closer I can get it to follow my load, the more money it will keep me from sending to SCE.

 

[Ampster]

I think Outback might recommend plugging micro inverters in where something else would normally go. I am not very experienced with electrical but these kind of instructions don't sit well with me.

I can clarify from my Outback Skybox experience. I have both micro inverters and a 3.8 kW Solaredge inverter connected to my critical loads panel. This is the only way to AC couple them when the grid is down. The critcal loads panel is disconnected from the grid connection when the grid is down and the Skybox then supplies the AC wave form and other attributes to allow these GT inverters to work. I hope this explanation sits better with you. If not, what are your specific concerns?

 

[Ampster]

Under the current California rules, it is not legal to sell back power that you charged from the grid, you can only sell power that the solar panels made

I think that is more of a contractual restriction per the Permission to Operate. I have asked the same question since I have AC coupled my Solaredge GT inverter to my Skybox. I see the battery discharging at the same time I see power being sold.

I haven't read your post completely but in the context of these rolling blackouts it seems that it would help the grid if thosevofvus with batteries would discharge into the grid during those peak times. Indeed Tesla has an arrangement in Vermont to aggregate Powerwalls to do just that. Tesla has applied to the California Public Utilities Commision for some permission to do something similar. I would hope that there may some day be a tarrif that would accommodate that. I have no desire to wear out my batteries or deplete my reserve capacity without some compensation.

 

[Ampster]

But when you want to have batteries as well, it throws a wrench into the whole equation.

No more so than any GT inverter system. Since anything installed in the past few years is UL 1741 SA compliant (and CA rule 21) any of them can be AC coupled to a hybrid inverter. The way I see the economics, a GT inverter system is the most economical way to harvest energy simply because the components in a GT inverter are fewer and less expensive. Leveraging a GT inverter with a hybrid inverter has to be more cost effective than having one or two hybrid inverters with the same solar panel capacity. The economics may turn on the specifics of an installation.

 

[Ampster]

They want you to use a certain percentage of micro inverters. And plug the micro inverters in were the generator would plug in. That sounds like some kind of hack.

Perhaps I can clarify and demystify. Any hybrid inverter that is AC coupled to a GT inverter (string or micros) will have some constraint on the size of GT inverters it can control. Tesla Powerwalls, my Outback Skybox, SolArk and the Schneider that @GXMnow is installing have their own limits based on how fast their firmware can interact with the standardized GT inverter frequency shift per Watt (as defined by UL 1741 SA). The electrical efficiency doesn't change if they have configured a generator port to be bidirectional or go direct to the critical loads panel.

 

[Ampster]

They only pay a net $0.02 to $0.06 for extra pushed back on the grid, and charge up to $0.40 when I need to buy it back as the sun goes down.

Sorry to make so many comments but your long post was so rich with useful information I thought it more productive to make specific comments individually than make a long response and get distracted.
You may not have been on your NEM agreement long enough for a True Up. The $0.02 that SCE pays is only at the end of the year based on the aggregate net balance accumulated over the year. You are being credited each month at the full TOU rate in effect when you sell it back. Therefore there is no benefit to being a net generator because any year end balance is reduced. Think of two buckets, one accumulating kWhrs and the other accumulating dollars. They don't reduce your kWh balance at year end True Up but you lose 80% of the dollar value because it is only paid out at the $0.02 wholesale rate.

However there is a way to game the system legitimatly. It is easiest if you have an EV but you can also do it with a hybrid inverter. I have been driving EVs as long as I have have had solar and TOU rates. Each year I have a credit balance in the dollar bucket (negative) and a net consumption balance (positive) in the kWh bucket. What happens at True up is the two wash and I just got one or two megaWatthours for free. It is very simple, I store energy i produce at a rate from $0.50 to $0.35 per kWh and charge my EVs at $0.15 per kWh.

 

[ArthurEld]

I can clarify from my Outback Skybox experience. I have both micro inverters and a 3.8 kW Solaredge inverter connected to my critical loads panel. This is the only way to AC couple them when the grid is down. The critcal loads panel is disconnected from the grid connection when the grid is down and the Skybox then supplies the AC wave form and other attributes to allow these GT inverters to work. I hope this explanation sits better with you. If not, what are your specific concerns?

Sorry Ampster, I get frustrated because this stuff is hard to understand. I want to thank you guys for sharing information that I need. It does ease my mind to hear that ac coupling doesn't lose a lot of efficiency.
I have been reading about your system and it sounds like you and GXMnow are successfully doing what I want. I need stop whining and read the manuals. I'm sure I will have questions. I'm curious about that electric VW I heard you mention too.

 

[Ampster]

I'm curious about that electric VW I heard you mention too.

It is a long story that started with buying an inexpensive kit to make my strand cruiser an ebike. Soon, from an online forum I learned how to buy a bigger controller and make bigger batteries.
Then one day while riding at 30 mph to the gym on my shorts with no helmet I realized I was a 65 year old man and needed some sheet metal around me so I could be there for my daughters graduation from graduate school.
An EV was an obvious solution but there weren't many in production them at a price I could afford.
It wasn't long before I found another forum about diy electric cars. I bought an old VW for $500 and starting assembling parts. A classic VW is an easy conversion because 4 bolts hold the motor and you can buy an adapter plate that connects an electric motor to the transmission. I was also inspired by Jack Rickards videos on EVTV.ME. All of that was while I was retired and newly divorced. I found a local distributor for Winston LFP batteries and had a fun extra car that had incredible 0 to 60 times. EVs have incredible torque starting at one RPM and I could beat anyone across the intersection for the first 60 feet. They call that the EV grin and i have purchased or leased a succession of EVs since then.

I continue to learn more as I pursue this hobby and it has been rewarding. I was fortunate to have been given a good formal education so now i have the tools to teach myself informally for the rest of my life.
I made the story as short as I could.