What have I messed up in this 5kW 48v system?

[jar349]

I know that the solar array is pitifully small for the system designed here, but other than that - do you see anything unsafe or outright incorrect here? Am I going to bond ground and neutral in the correct place? Are the cables correctly sized? Am I missing breakers anywhere?

 

[FilterGuy]

I assume you have followed all the controversy about this arrangement....Make sure to remove the screw that enables the N-G bond in the 5000ES (That is what makes it the "US Model"). Even then, if you ever hook to the grid for charging it can be problematic if the inverter goes into pass-through mode.

* The metal case of the transformer should be grounded.

* Yes, the breaker box is an ok place for the N-G bond.

* What is the purpose of the combiner box? With only one string of panels, it is not really needed. Are you planning on adding two or more strings later? (You would need the combiner box if you have 3 or more strings). I did not do the calculations but the 10AWG seems ok for the PV string. If you plan on adding mores strings later the output circuit from the combiner box to the inverter may need to be larger.

Fusing & Wire Sizing guidelines for solar panels

To get the paper, click on the orange'' button at the top of the screen. This resource is intended to help the user understand when they need to add Over Current Protection Devices (OCPDs - Fuses or Breakers) to the solar panel array and what...

diysolarforum.com

* If you want to be to code you will need arc fault protection and that is sometimes built into combiner boxes. Other things that will be needed for code is ground fault protection and rapid shutdown...... but I guess you aren't going for code compliance because growatt is not code compliant.

 

[jar349]

FilterGuy thank you for taking time to respond. Yes, I have been following that controversy. I ordered directly from Signature Solar, so there is no screw to remove - luckily. I had been planning to use the grid to pass through but I'm not going to do that any longer. Honestly, I made that choice before this controversy: the cost of the copper to run to the inverter was so much that it would be cheaper to buy 2 more solar panels instead.

The metal case of the transformer should be grounded

I don't know if it has a place to ground the case, but if it has one I will connect it. (It is still on the way here so I don't have it yet)

Yes, the breaker box is an ok place for the N-G bond

Thank you for confirming this. This has been my greatest fear of getting wrong. I thought for a while that I might bond G&N in the combiner box but that would mess up my SPD, so the service panel was all that was left.

What is the purpose of the combiner box?

I've intentionally chosen components that will permit me to add more panels. I will leave a pull string in the conduit for future PV strings. I just want to know how much I'm going to generate from the 4 I have so that I will know - for sure - how many I need for future plans.

If you want to be to code you will need arc fault protection and that is sometimes built into combiner boxes.

I will have to look into this because I hadn't heard about it before. I thought that the DC breakers are made to suppress the arc when they trip?

but I guess you aren't going for code compliance because growatt is not code compliant

I don't want to feel anxiety over the safety of the system. It will be accessible to my grade-school-aged children, so I need it to be safe but not necessarily up to code. They are old enough that I can tell them what not to touch and they will listen.

 

[Quattrohead]

Double pole breaker on the output of the growatt, will protect everything in the event of a problem. No breakers on battery leads, the EG4 already has those.
Actually move the transformer connection to the breaker box and use your 25A breaker to input from the growatt, will save you a breaker

 

[jar349]

Double pole breaker on the output of the growatt, will protect everything in the event of a problem

Everything? I would think that it would protect the transformer from a misbehaving inverter, but how does the breaker on the output of the growatt protect everything?

No breakers on battery leads, the EG4 already has those.

I'm super-curious to hear more about this? The breaker on the positive terminal of the battery lead was suggested by Signature Solar. This is worth investigating, imo.

Actually move the transformer connection to the breaker box

Please forgive my clear lack of understanding - I'm only 3 months into learning about all of this. I believe that my transformer is already connected to the breaker box via the double pole breaker? You clearly mean for me to connect it to the breaker box in some other way, but I don't know how you mean?

and use your 25A breaker to input from the growatt,

If I put a double pole 25A breaker in between the growatt and the transformer... would I not need to purchase a wholly new service panel for that one breaker?

I am sorry but I am not able to take your feedback, which I value, and picture in my head a new diagram of how things are laid out. Hopefully my questions should clarify where I'm confused.

 

[eXodus]

Wonder why you are using a combiner box? Future extension? For 4 panels in series a box is not needed.
Why did you choose the SPF 5000 ES over the 6000T DVM (which already got Split phase)?


5000 ES = $900 + Split phase transformer $350 = $1250 +wiring and labor.
6000T DVM = $1100-1200
I don't know - with the 6000T and the MPP 6kw products available I don't really see a reason anymore to mess with a Transformer.


Usually ground and neutral are bonded at the main service panel. But I would assume that the autotransfomer or inverter also bonds those. Look up the manual and measure!! if you got bonds somewhere else. I think part of the controversy was that screw that bonds ground and neutral in the 5000 ES. Measure all your devices before you connect them. So you know.

 

[acdoctor]

I would definitely breaker the output of inverter. Transformers have a tendency to burn up. Short out. Breaker will trip. Replace transformer. The current configuration. Transformer shorts overloading inverter. Now replacing both.
If batteries are parallel I would have the 125 amp breaker. If it is two 24 volt in series to get 48 volts then they are 1 battery and no need. Cables like Romex, Tray cable and the like are not supposed to be in conduit.

 

[jar349]

Wonder why you are using a combiner box? Future extension? For 4 panels in series a box is not needed.
Why did you choose the SPF 5000 ES over the 6000T DVM (which already got Split phase)?


5000 ES = $900 + Split phase transformer $350 = $1250 +wiring and labor.
6000T DVM = $1100-1200
I don't know - with the 6000T and the MPP 6kw products available I don't really see a reason anymore to mess with a Transformer.

Combiner box is for future extension and it gives me a place to install a surge protection device (midnite solar).

This is my first attempt at DIY off-grid solar, so it's possible that I chose the wrong inverter. I picked the SPF 5k ES because of its higher PV input voltage, which I thought would make my PV array configuration a lot easier since I can put up to 6 of my chosen solar panels in series. If I were doing it all over again, I would probably not have gone this route. Trying to figure out how to wire the inverter and transformer into a service panel is complicated by how many different ways I've seen it done on youtube. Having it already done for me in the inverter would have been a lot less hassle.

Usually ground and neutral are bonded at the main service panel. But I would assume that the autotransfomer or inverter also bonds those. Look up the manual and measure!! if you got bonds somewhere else. I think part of the controversy was that screw that bonds ground and neutral in the 5000 ES. Measure all your devices before you connect them. So you know.

I think that's what I have done, right? The "main service panel" is the siemens main lug panel in my diagram. It just feels weird to bond it there because it's "downstream" from my whole solar system. Meaning, the combiner box --> inverter --> transformer --> service panel.

Because I purchased the inverter directly from Signature Solar, I can assume that the screw is not present and that ground and neutral are not bonded in the inverter.

Does this seem right to you?

 

[jar349]

I would definitely breaker the output of inverter. Transformers have a tendency to burn up. Short out. Breaker will trip. Replace transformer. The current configuration. Transformer shorts overloading inverter. Now replacing both.

It looks like I could use another of that same exact Siemens service panel to add breakers between the inverter and transformer. Two double-pole 25A breakers. One is a backfeed breaker coming from the inverter to power the panel. The other powers (and protects) the input of the transformer.

 

[Quattrohead]

Line 1 and Line 2 from the inverter right to your breaker box via a 25A dual pole breaker. Transformer L1 to CB box L1, Transformer L2 to CB box L2 at the top of your CB box. Neutral to neutral in breaker box. Connect your ground rod to the ground in the CB box and the neutral by the supplied screw if not already installed. All metal boxes need to be grounded, including the inverter.
The 25A CB will protect everything from overloads, inverter,transformer and even loads. The loads should trip their own CB first though.
You do not need any CD after the batteries, otherwise why did they bother to fit them ?

 

[Quattrohead]

Talking drunk bollocks apparently.

 

[eXodus]

Because I purchased the inverter directly from Signature Solar, I can assume that the screw is not present and that ground and neutral are not bonded in the inverter.

Signature Solar is usually good about that.

Still when in doubt just measure for assurance- Neither the input nor the output of the inverter should have ground and neutral connected.

This is my first attempt at DIY off-grid solar, so it's possible that I chose the wrong inverter. I picked the SPF 5k ES because of its higher PV input voltage, which I thought would make my PV array configuration a lot easier since I can put up to 6 of my chosen solar panels in series. If I were doing it all over again, I would probably not have gone this route.

When I commented I wasn't sure if you already had the components purchased.

It's always the first time for someone. You live and your learn. We all got our fair share of trial and errors on this board.
I built 5 systems in the in 12 years and in retrospective I still find things now I would have done differently. New technology comes around and stuff gets simpler or better integrated. You should see the wall of boxes a Hybrid inverter replaces. Amazing

One way you tried to futureproof with the combiner box - which enables parallel strings - which means you also don't need the high voltage, the 5000 ES can take in. Sure 6 panels in series makes wiring on the roof easy, Yet adding another wire run from the roof isn't much more expense and complex. You can make the autotransfomer setup work, just be very careful, measure loops. and get one of those voltage sensing Screwdriver thingies to check all your cases for voltage when you turn it on. - Be Safe!

 

[Struc]

Actually are you still planning to run 240v appliances ? If not return the transformer.

What are you talking about??

 

[Quattrohead]

Wrong thread haha.