11.8Kw Ground mount and 3-SPF Growatt 5000 ES, Grid pairing and backup Generator. But will it work?

[Jim Lee]

It would depend upon what you are running, the GW 12Kw unit is a low frequency inverter, it has a 36Kw surge capability for several seconds. If you are starting motors, this is an advantage. Surge rating on the SPF5000ES is 10Kw but it is a high frequency inverter and surge capability is much shorter for it.

I've mentioned this before, your amps from PV are over the PV amp rating for SPF5000ES. You will need to add additional SCC's to lessen the amps to the SPF5000ES SCC. With either choice, the GW12Kw or the SPF5000ES, additional SCC will be required and you will have to run series connected panels in single strings.

Edit: I thought your setup and discussion was familiar, I went back and looked and yes, we have had this discussion several times over multiple threads. It basically is that you want to run the SPF5000ES with 2 auto transformers and want someone to tell you that it is perfectly fine with your design because Signature Solar won't do that (red flag) . For that reason, I'm bowing out of this discussion. Many have commented in the multiple threads you have had on the design of your system, many had good advice.

Concerning your edit: The problem is I have asked questions on several sites and could not figure out how to set up my system to work using the individual spot advice from several people. I thought that if I drew up a plan from advice given by several people (some experienced and some maybe not) Someone with some Electrical or Engineering expertise would chime in and help get a system up and running. From what I see, several DIY'ers are trying to do the same thing I am. Wouldn't working on this to help figure out how to get it to work or show that it will not work help a lot of non professional enthusiastic DIY'ers. Isn't that what this forum is for. I've seen your responses on several Threads.(apparently 900 comments)
Please, If I ask you how to cook a steak, Please don't answer "EAT PORK". I'm not looking for someone to say it is perfectly fine. Unless they think it is. I'm looking for potential problems, which I know there are some. example: What make and size of breakers are needed between the IMO disconnects, the batteries and the Growatts and where can I get them. What is the "ac in" on the GW used for. Is it grid battery charging only or is it what is used to " pair with the utility if the solar is not enough to power a load" as I Quoted from the Growatt information sheet. Also , what does that quote even mean. I have my ideas but I'm not sure I have it right. One thing I know is I am extremely tired of not being able to get help before I purchase, then after I make the purchase AVERYONE KNOWS EXACTLY WHAT I DID WRONG AND WANDERS WHY I DID IT THAT WAY.

 

[Quattrohead]

Ask your questions 10 different ways until you get the answer you are looking for.
Wether a professional supply house or an internet forum, eventually they get fed up answering questions that don't have the answer you want.
Sorry and out too.

 

[Struc]

If I switch the Generator interlock switch that would enable Grid only and shut of all power to solar. Both transformers and all 3 inverters will shut down. Am I missing something here? It seems if I put in a 2nd transfer switch, it would do the same thing as the generator interlock. ???

The inverters will not shut down - they will simply be disconnected from the house, and will still be powering the 2nd Subpanel - unless you plan on doing all that manually before switching over to grid? The power for the transformers is the 2nd Subpanel. That Neutral will still be carried through into the 1st subpanel, tied with the neutral with grid power. Breakers don't switch on and off the neutral - only the 2 hot legs.

Will it cause an issue? I really don't know to be honest, but I know that other complicated thread talking about the neutral did not have grid neutral tied to transformer neutral. Seems to me powering the transformer with inverter power and connecting that to grid seems like a bad idea.
Somebody smarter than me should confirm that, though.

 

[Zwy]

The inverters will not shut down - they will simply be disconnected from the house, and will still be powering the 2nd Subpanel - unless you plan on doing all that manually before switching over to grid? The power for the transformers is the 2nd Subpanel. That Neutral will still be carried through into the 1st subpanel, tied with the neutral with grid power. Breakers don't switch on and off the neutral - only the 2 hot legs.

Will it cause an issue? I really don't know to be honest, but I know that other complicated thread talking about the neutral did not have grid neutral tied to transformer neutral. Seems to me powering the transformer with inverter power and connecting that to grid seems like a bad idea.
Somebody smarter than me should confirm that, though.

It starts here: https://diysolarforum.com/threads/d...pf-5000-es-grid-backup-neutral-bonding.29717/

 

[Jim Lee]

The inverters will not shut down - they will simply be disconnected from the house, and will still be powering the 2nd Subpanel - unless you plan on doing all that manually before switching over to grid? The power for the transformers is the 2nd Subpanel. That Neutral will still be carried through into the 1st subpanel, tied with the neutral with grid power. Breakers don't switch on and off the neutral - only the 2 hot legs.

Will it cause an issue? I really don't know to be honest, but I know that other complicated thread talking about the neutral did not have grid neutral tied to transformer neutral. Seems to me powering the transformer with inverter power and connecting that to grid seems like a bad idea.
Somebody smarter than me should confirm that, though.

Thanks, I'll be looking close at that, but really that is above my level of knowledge. Not sure what I'll do. Wait to purchase and build until I know for sure. I'm already building the ground mount. I may just end up with 2 strange looking storage sheds.

Ask your questions 10 different ways until you get the answer you are looking for.
Wether a professional supply house or an internet forum, eventually they get fed up answering questions that don't have the answer you want.
Sorry and out too.

The Only question I have asked is will it work. No one has said it will not work and NO professional Supply house has given ANY advice except DIY. I thought that is EXACTLY what I'm doing here asking these Questions. DIY. Some changes have been made and I'm sure more are needed. I just don't think I am at the point after a couple of negative responses to toss the whole Idea and start over with something different. I WOULD like to see a diagram of your Solar set up and see how you got it to work perfectly.

 

[Jim Lee]

It starts here: https://diysolarforum.com/threads/d...pf-5000-es-grid-backup-neutral-bonding.29717/

I'm collecting parts for a near identical system (I'm only doing 2xGrowatt to start), right down to the NG generator (mine is 15kw). All looks good and is very close to the design in my head, but I have more subpanels I need to feed due to the way my property was set up when I bought it.

My only bit of advice would be to go 6s1p on that last string of panels. Apparently the Growatt inverter will handle more amps, but will only use 18A, so might as well boost up the voltage instead.

Guessing you'll be running 10awg PV or THWN cable from the panels to the inverters?

Engineer775 is a guy on YouTube that builds solar systems for a living.

Thanks, I change the 3s2p to 6s1p. I plan on 10awg from the panels. I'd sure like to see your plans when you get them done. I might be consulting Engineer775 before this is done.

 

[Jim Lee]

The inverters will not shut down - they will simply be disconnected from the house, and will still be powering the 2nd Subpanel - unless you plan on doing all that manually before switching over to grid? The power for the transformers is the 2nd Subpanel. That Neutral will still be carried through into the 1st subpanel, tied with the neutral with grid power. Breakers don't switch on and off the neutral - only the 2 hot legs.

Will it cause an issue? I really don't know to be honest, but I know that other complicated thread talking about the neutral did not have grid neutral tied to transformer neutral. Seems to me powering the transformer with inverter power and connecting that to grid seems like a bad idea.
Somebody smarter than me should confirm that, though.

Newest drawing updates today 12/14/21. I put ? on some breakers, surge protectors and wire sizes that I'm not sure of.

 

[Struc]

Newest drawing updates today 12/14/21. I put ? on some breakers, surge protectors and wire sizes that I'm not sure of.

For the 125A feed between panels you will need at least 2AWG copper. To keep costs down, I'm doing 2/2/2/4 Aluminum from Southwire, found at places like Lowes and Home Depot. It's $1.50/ft in custom lengths, but only good for 100A. Because of the costs, and the distance to my NG Generator, I'm also using it for my transfer switch to the generator disconnect.

 

[Jim Lee]

For the 125A feed between panels you will need at least 2AWG copper. To keep costs down, I'm doing 2/2/2/4 Aluminum from Southwire, found at places like Lowes and Home Depot. It's $1.50/ft in custom lengths, but only good for 100A. Because of the costs, and the distance to my NG Generator, I'm also using it for my transfer switch to the generator disconnect.

Thanks, I'll change it on my plans.

 

[robby]

Ask your questions 10 different ways until you get the answer you are looking for.
Wether a professional supply house or an internet forum, eventually they get fed up answering questions that don't have the answer you want.
Sorry and out too.

And this Jim Lee guy is the same guy now in another thread telling me my Mind is closed to new tech and that he knows of better solutions. In 9 days he has gone from asking for basic advice to being an expert!
Good luck Jimmy with that Transformer and the 5KWh of daily wasted power you will be using just to power those three Growatts and I hope that Transformer breaker never trips or your household items will be toast.

 

[Tony Scott]

So far as I can tell, it'll work. Note that the three inverters also have parallel cables that go between them, which you haven't included in your diagram.

I'd suggest you have your welder and hot water on the solar as well, but I'm sure you understand your needs better than I.

The only thing that needs to be understood and perhaps mitigated is that the two autotranformers only handle 5kW each, and you're generating up to 15kW of power. While exceptionally unlikely, failure in one could lead to a cascade failure in the other if the imbalance is over 5kW, which will result in damaging nearly every 120v device at the same time. Adding a third one would provide some peace of mind. Temperature monitoring which forces the inverters to shutdown might also resolve that - the autotransfromers have temperature sensors in them, but they aren't connected to anything.

It's the same direction I'm leaning towards, though, and I really like the panel that handles those transformers and the inverters together before going to the next panel. Right now I have the autotransformer right on my main panel, but my inverter supplies split phase so it's only meant to help the imbalance in my home.

One transformer would be more than enough you can add 2,3,4 transformer’s if you want but this idea of some catastrophic failure on a transformer, yeah makes no sense. The inverters would fail long before a transformer would ever go bad even signature solar says one is more than enough. Now he has a welder so he may need two transformers if he’s gonna put a welder on there depending on what voltage the welder is pulling. Again use as many as you want too, but I would buy a backup inverter first.

 

[Jim Lee]

One transformer would be more than enough you can add 2,3,4 transformer’s if you want but this idea of some catastrophic failure on a transformer, yeah makes no sense. The inverters would fail long before a transformer would ever go bad even signature solar says one is more than enough. Now he has a welder so he may need two transformers if he’s gonna put a welder on there depending on what voltage the welder is pulling. Again use as many as you want too, but I would buy a backup inverter first.

 

[Jim Lee]

This is my last revision. It is laid out exactly like it is going into my garage. (Hopefully my last revision) I originally planned to get 3 inverter and one extra for future backup. Since then I've learned that I can just hook it up and if I don't need it I can just turn it off with no problems. ( Figured I might as well buy it now with a 26% tax break than wait till later when it cost more and no tax break) Also with 4 inverters I can run all my panels in 4 series with no paralleling. As far as the transformers go, it seems most people don't understand what a split phase transformer is. They think I will be powering through it I think and not just balancing the 120Vac phases. The second one is just for peace of mind. My welder and Hot water 240Vac got moved because I don't have a welder and no electric hot water heater. (Geothermal Heating and Air conditioning preheats my hot water which then goes through a gas on demand Hot water supply) I built my house 6 years ago and those along with 240Vac for car charger which I don't have were put in for future convenience just like I'm doing planning for a 4th, 5th or even a 6th Inverter. Better to plan ahead for very little dollars and not need it than have to tare down walls to add later. If you see any thing that should be changed on my plans, please feel free to cretic it. ALL suggestions are considered and appreciated.

 

[Prefersdirt]

This is my last revision. It is laid out exactly like it is going into my garage. (Hopefully my last revision) I originally planned to get 3 inverter and one extra for future backup. Since then I've learned that I can just hook it up and if I don't need it I can just turn it off with no problems. ( Figured I might as well buy it now with a 26% tax break than wait till later when it cost more and no tax break) Also with 4 inverters I can run all my panels in 4 series with no paralleling. As far as the transformers go, it seems most people don't understand what a split phase transformer is. They think I will be powering through it I think and not just balancing the 120Vac phases. The second one is just for peace of mind. My welder and Hot water 240Vac got moved because I don't have a welder and no electric hot water heater. (Geothermal Heating and Air conditioning preheats my hot water which then goes through a gas on demand Hot water supply) I built my house 6 years ago and those along with 240Vac for car charger which I don't have were put in for future convenience just like I'm doing planning for a 4th, 5th or even a 6th Inverter. Better to plan ahead for very little dollars and not need it than have to tare down walls to add later. If you see any thing that should be changed on my plans, please feel free to cretic it. ALL suggestions are considered and appreciated.

Dude, I am sooo soaking up what you are doing. This is almost exactly what I want to do - except even more battery storage. A question about your arrays. Why are you putting the panels in portrait orientation vs landscape? A comment somewhere talked about landscape helps deal with shading issues - less likely to shade part of a panel.

What did you use to create the diagrams? (Hope this was not earlier in the thread).

 

[Jim Lee]

Dude, I am sooo soaking up what you are doing. This is almost exactly what I want to do - except even more battery storage. A question about your arrays. Why are you putting the panels in portrait orientation vs landscape? A comment somewhere talked about landscape helps deal with shading issues - less likely to shade part of a panel.

What did you use to create the diagrams? (Hope this was not earlier in the thread).

The program I use is a part of "Punch, Home Design and Landscape Pro" called "detail", it works similar to a Generac cadd program I used for years. I've had it for about 7 years and I used it (The 3D Part) to design my house I built 6 years ago. I went to vertical panels for several reasons. 1. I'm 69 years old and do a lot of work myself and no panels in the middle to take out seemed necessary. It would be almost impossible for me to do, but only stacked two high seemed easier to handle if needed in the future. 2. I was out checking my ground mount on December 21 (The lowest sun day) and I didn't have much of a shade problem. I'm on 2.5 acres and could cut trees if needed. To the best of my knowledge the Bi-Facial Half-Cut panels are split into 2 halves and have 3 Diodes to minimize shading problems and allow up to 25% (I think) added solar collection from reflections under the panels. the rear array is taller because I plan to park my tractor under it and it helps with shade problems.

 

[James Showalter]

the drawings here are really good. 2 things would be a good improvement:
-make the output panels a "main breaker" type so that you can shut off all inverters at once
-combine all the AC inputs on a similar main breaker panel before landing on a 125A breaker at the main load panel

If you use the "AC combiner" strategy on you system you will be able to manage it more effectively.

you might consider a 100-125A Bypass switch https://www.homedepot.com/p/GE-100-...ency-Power-Transfer-Switch-TC10323R/100171587 for the AC in and AC out panels, connecting your load panel to the load side, the AC out of the inverters to the Generator side and the AC in to MDLP at your house.

This will allow for easy transfer from inverter back to grid in case of maintenance, upgrade or repair in the future.

We do not do drawings but we sure do comment on them.

 

[PLCdude]

the drawings here are really good. 2 things would be a good improvement:
-make the output panels a "main breaker" type so that you can shut off all inverters at once
-combine all the AC inputs on a similar main breaker panel before landing on a 125A breaker at the main load panel

If you use the "AC combiner" strategy on you system you will be able to manage it more effectively.

you might consider a 100-125A Bypass switch https://www.homedepot.com/p/GE-100-...ency-Power-Transfer-Switch-TC10323R/100171587 for the AC in and AC out panels, connecting your load panel to the load side, the AC out of the inverters to the Generator side and the AC in to MDLP at your house.

This will allow for easy transfer from inverter back to grid in case of maintenance, upgrade or repair in the future.

We do not do drawings but we sure do comment on them.

Hence I added an extra charge controller.
Your 3x inverter diagram is quite complicated and uses transformers that whilst reliable, protecting them with a breaker AS YOU SHOULD means that IF the breaker were ever to trip, you will stress and fry various 120v devises in your home. Its a bodge to make non USA equipment to work here.
Get the proper stuff and do it right.

With little modification you do need to worry about burning anything. I’m electrical engineer and intend to deploy similar system with 3 ea 5k es inverters in parallel. My design for 120v side will be different since I will be using 10KVA transformer with 240VAC primary and 120/240 secondary feeding 120vac panel Instead using auto transformer.

 

[Hedges]

Couple of things, some others have commented on first one.

If you have 240V inverter output and rely on auto-transformers to establish 120/240V split phase, if those auto-transformers go offline you fry some 120V electronics.
I've thought about this issue before, and one solution is to gang the breaker for autotransformer to a breaker feeding the panel. That way, if the 30A breaker on auto-transformer trips it also shuts off 50A breaker feeding panel.
Difficulties with that include you have 2x autotransformers and multiple inverters, may exceed ability to gang. And, spacing between breaker levers may make ganging difficult.

Another possible was to address:
1) Feed inverters to a panel with only 240V loads. No issue with lost neutral.
2) With 30A breaker from 240V panel, feed a sub panel with hardwired autotransformer (no breaker) and multiple 120V loads. If 30A breaker trips disconnecting transformer, loads are shut off and protected. (better to use one 10kW transformer and larger breaker.)

I would like to have a thermal protector on the transformer. Ideally that would work by tripping the 30A breaker remotely. Also fan cool.

All these fancy breaker configurations may be easier to accomplish with DIN rail hardware.

Other possible issue:
240V from grid, L1 and L2, go to Growatt input.
Output of Growatt goes to autotransformer, establishing grounded neutral as midpoint.
If grid goes down, Growatt disconnects from its AC input. Does that only disconnect what it considers Line (your L1)? Or does it disconnect what it considers Neutral as well (your L2).
If It's Neutral remains connected to its output L2, 120V away from grounded Neutral on your sub-panel, it backfeeds 120V into your AC grid connection L2. Trouble is, grid is down so you're now backfeeding grid.

You need to determine if Growatt has a 2-pole disconnect, isolating both AC input wires Line and Neutral.
If you have one on hand, should be able to measure with meter for continuity.

 

[EchoPapa]

Watch this on grounding the 5000es. SS is modifying or having GW modify the internal ground to neutral inside the 5000es

 

[Struc]

Post the thread. Posting just that video is very misleading. Lots of additional information has been posted about that video.

Safety hazard w/ Growatt 5000ES (European version) when connected to American grid

If you're using a growatt 5000es (European model that I don't use in my videos) with an auto transformer, you need to watch this video. The output of the inverter bonds the ground and neutral, which is designed for use with European grid. Conversely, American grid uses center tap transformer to...

diysolarforum.com

 

[solardad]

@Jim Lee what did you end up doing? Thanks

 

[Jim Lee]

@Jim Lee what did you end up doing? Thanks

This is what I ended up doing.