.

realpinochet said:

I generally understand residential power but new to the solar inverter. If what you're saying then why does some inverters like the solark and other HF inverters say they do not have a transformer?

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High frequency inverters don't have transformers.
Low frequency inverters do. And handle surges much better. (Less dips in voltage from a surge)
High frequency inverters are cheaper and lighter, which makes them preferable in a lot of situations. But, low frequency inverters are the better option. If you have the money, room, and a friend to help you get it on the wall.
I chose the best of both worlds. A high frequency inverter, paired with a transformer.
Low cost and highly capable.

I agree 100% that taking out the screw doesn't make it a US version. As I've mentioned before a few times and is mentioned in the video that I posted, the PCB is designed specifically for the us market. It is a completely different part. Just removing the screw from the EU version "could" prevent any issues, but there is no telling over time. The likelihood of failure is much greater when just removing the bonding screw. With the version SS carries, the board was designed to never have had a bonding screw in place. It is much better insulated.

I have no doubt that there are people out there with systems running great with the EU version. If you are completely off grid I doubt you would ever see an issue. If you could save $300 per inverter, I wouldn't argue to stop you. The only downfall would be that you can only get 230V out of a EU version.

With the US version, the transformer is used to balance the output so you get 2 lines of 120V. After rereading some of the previous posts, I don't think that was ever explained. I don't know the application of using a transformer with the EU version, my understanding is that it can't be done. But I have heard that people were doing it. I don't really know for sure as I've never actually had my hands on that model.

timselectric said:

High frequency inverters don't have transformers.
Low frequency inverters do. And handle surges much better. (Less dips in voltage from a surge)
High frequency inverters are cheaper and lighter, which makes them preferable in a lot of situations. But, low frequency inverters are the better option. If you have the money, room, and a friend to help you get it on the wall.
I chose the best of both worlds. A high frequency inverter, paired with a transformer.
Low cost and highly capable.

Click to expand...

Something like the EG4 6000ES is an example of a LF inverter that works well for ppl in various applications as it can output 120V or 240V due to having an internal transformer. IMO LF inverters are great and less hassle, but HF is certainly more cost effective.

BenFromSignatureSolar said:

Please just check out video. First few min should clear this up.

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"Offgrid" as you say in the video?
Or also with utility grid on input? (documentation for auto-transformer shows grid input.)

I watched the first 5 minutes. At normal speed.
A video is not documentation. It can't be referred to for the purpose of connecting hardware, or checking if the installation was as instructed, or if fault currents are handled correctly so no hazardous voltages appear on appliance chassis.

What I would like is a schematic showing grid feeding inverter, with your new transformer and loads on the output.
It needs to show all ground and neutral connections.

On your website I find "Growatt 5kW Split Phase Transformer | ATS 5000T-US" with some documents (data sheet and "Manual", a one-page sheet.)


Of what I can make out of the schematic, when on-grid it uses an auto-transformer to derive a neutral (not separately derived; it is not galvanically isolated from grid.) This neutral is not bonded to ground. To the extent there is a load imbalance, neutral will deviate from ground. Likely up to a few percent of line voltage ("regulation" of transformer). At higher currents, breaker would trip and disconnect. But it would present excessive voltages on neutral for the duration of overload until breaker does trip.

When disconnected from grid and using inverter output, it uses an auto-transformer to derive a neutral, and there does not appear to be a neutral-ground bond.

Other inverters which are UL listed for mobile applications have an all-pole disconnect from grid (including neutral) and create a neutral-ground bond when disconnected from grid. (Many of those are single-phase.) Victron has an auto-transformer for an application similar to yours and it includes both over-load protection (which you provide) and neutral-ground bond (which you do not.)

I don't believe your auto-transformer (even if UL listed), when used with your 240V inverter, and wired according to the schematic provided, complies with NEC.

If you have a schematic showing how to use your equipment in a compliant manner, please post it.
If that auto-transformer is in fact UL listed, I think the usage which complies with UL listing must be documented.

timselectric said:

High frequency inverters don't have transformers.
Low frequency inverters do. And handle surges much better. (Less dips in voltage from a surge)
High frequency inverters are cheaper and lighter, which makes them preferable in a lot of situations. But, low frequency inverters are the better option. If you have the money, room, and a friend to help you get it on the wall.
I chose the best of both worlds. A high frequency inverter, paired with a transformer.
Low cost and highly capable.

Click to expand...

That's what I arrived at from my own earlier research but you said everything had a transformer which made me rethink if I misunderstood HF inverters and how a HF inverter like the solark could have split current without a transformer.

BenFromSignatureSolar said:

I agree 100% that taking out the screw doesn't make it a US version. As I've mentioned before a few times and is mentioned in the video that I posted, the PCB is designed specifically for the us market. It is a completely different part. Just removing the screw from the EU version "could" prevent any issues, but there is no telling over time. The likelihood of failure is much greater when just removing the bonding screw. With the version SS carries, the board was designed to never have had a bonding screw in place. It is much better insulated.

I have no doubt that there are people out there with systems running great with the EU version. If you are completely off grid I doubt you would ever see an issue. If you could save $300 per inverter, I wouldn't argue to stop you. The only downfall would be that you can only get 230V out of a EU version.

With the US version, the transformer is used to balance the output so you get 2 lines of 120V. After rereading some of the previous posts, I don't think that was ever explained. I don't know the application of using a transformer with the EU version, my understanding is that it can't be done. But I have heard that people were doing it. I don't really know for sure as I've never actually had my hands on that model.

Click to expand...

"The only downfall would be that you can only get 230V out of a EU version"

You do realize people bought watts247 "EU" inverters and added a auto transformer just like you're suggesting to do with SS versions? Maybe I'm misreading your comment above. As for the bonding screw.. from what I've read here the difference with SS version is the trace on the pcb isn't there at all. OK, I get what your saying but don't see this as a significant difference technically. This just keeps your people from having unbox every imported "EU" inverter and removing a screw or more likely forgetting to and shipping it out with the screw in place and causing a liability issue. I'm not debating if this solution works etc...I'm saying at this point and from what you've reveled it seems to be more of a play on marketing. Thanks for taking the time to update us here on the facts.

I have two 120V inverters, synchronized 180 degrees out of phase to make 120/240V split phase. (actually, four inverters, but same idea.)
They happen to be low-frequency transformer type, but HF works the same.

I tested with an auto-transformer as well and that partially re-balances load so I can have more load on one phase than the inverters on that phase provide. It doesn't allow all power from both phases to appear on one phase. Whether it would or not depends on "regulation" of the transformers (voltage sag due to IR drop) and how much sag the inverters allow. I think up to 100% on one phase may be possible.

Using 240V into a large enough transformer, auto- or isolation-, you can deliver 100% of inverter power to a single 120V phase. If done with an auto-transformer there is the issue of bonding the non-separately-derived neutral to ground, and possibly having "objectionable" currents in ground. I think if the source (inverter or generator) is floating, preferably straight 240V without anything called neutral, then auto-transformer is OK.

"Low frequency"? I've decided there is nothing inherent in a low-frequency transformer that helps with surge. Current through transistors from battery to transformer is what defines surge capability. For HF design, current it is able to boost to HV rail and current through transistors to output define surge. The inherent difference I do see is that boost converter of HF inverter can only transfer as much energy as it can store in an inductor. LF inverter doesn't store energy (except in inductors used for buck converter to make sine wave), and even if those inductors saturate the transformer can be driven square-wave during surge.

realpinochet said:

"The only downfall would be that you can only get 230V out of a EU version"

You do realize people bought watts247 "EU" inverters and added a auto transformer just like you're suggesting to do with SS versions? Maybe I'm misreading your comment above. As for the bonding screw.. from what I've read here the difference with SS version is the trace on the pcb isn't there at all. OK, I get what your saying but don't see this as a significant difference technically. This just keeps your people from having unbox every imported "EU" inverter and removing a screw or more likely forgetting to and shipping it out with the screw in place and causing a liability issue. I'm not debating if this solution works etc...I'm saying at this point and from what you've reveled it seems to be more of a play on marketing. Thanks for taking the time to update us here on the facts.

Click to expand...

I have seen that people are using the EU version in that application. But again, I've just never used this version so I can't speak to how it's being done.

Hedges said:

Victron has an auto-transformer for an application similar to yours and it includes both over-load protection (which you provide) and neutral-ground bond (which you do not.)

Click to expand...

In a mobile application the N/G bond will take place in the main load panel much like an off grid app.

The Mid-point transformer is UL 1741 compliant. Intertek was the testing facility. However, I do not have a schematic available to share here.

Apologies if that leaves some of your questions unanswered. But that's the info that I have available to share.

realpinochet said:

but you said everything had a transformer

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What i said was "Transformers are used in every system all over the world. A Transformer is how you have split-phase in your house right now"

I should have said "Transformers are used in every >grid< system all over the world. A Transformer is how you have split-phase in your house right now"

The point being that transformers are used widely.
In my 38 years in the trade, I have installed more than a couple hundred. The only thing that makes the SPF-5000-ES different between the US and European version, is the bonding to ground. If that doesn't exist, it's compatible with any system in the world.

timselectric said:

What i said was "Transformers are used in every system all over the world. A Transformer is how you have split-phase in your house right now"

I should have said "Transformers are used in every >grid< system all over the world. A Transformer is how you have split-phase in your house right now"

The point being that transformers are used widely.
In my 38 years in the trade, I have installed more than a couple hundred. The only thing that makes the SPF-5000-ES different between the US and European version, is the bonding to ground. If that doesn't exist, it's compatible with any system in the world.

Click to expand...

Yes..again I understand my poco uses a transformer to provide the neutral to me for split phase. I thought you were saying HF uses transformers to provide split phase which is why I was asking for clarification as I thought perhaps I misunderstood them or the vendor was lying in saying they didn't have a transformer. Thanks for the update.

BenFromSignatureSolar said:

In a mobile application the N/G bond will take place in the main load panel much like an off grid app.

The Mid-point transformer is UL 1741 compliant. Intertek was the testing facility. However, I do not have a schematic available to share here.

Apologies if that leaves some of your questions unanswered. But that's the info that I have available to share.

Click to expand...

Wouldn't a valid solution provide professional documentation vetted by the vendor or qualified 3rd party? It would behoove all parties involved if there was proper wiring diagrams and the caveats regarding the different ways to wire this solution both on grid, off grid, mobile etc. Also, if a generator is used does it provide the N/G bond etc? If you're going to provide videos, which are not proper forms of documentation, then you should provide videos in different usage scenarios as mentioned above; then show us if voltage is going over the ground wire in each case usage etc. There was a gentlemen on youtube, albeit using mpp with the grounding screw removed, that had things bonded at the main panel as he should. When the inverter was using the grid it was fine but he found out when the grid was off and he was inverting he had significant voltage on the ground wire. I'm not sure what he did or if he resolved it as there was no updates.

BenFromSignatureSolar said:

In a mobile application the N/G bond will take place in the main load panel much like an off grid app.

The Mid-point transformer is UL 1741 compliant. Intertek was the testing facility. However, I do not have a schematic available to share here.

Apologies if that leaves some of your questions unanswered. But that's the info that I have available to share.

Click to expand...

UL Listed or not, I don't believe the transformer/breaker/switch SS is selling can be used in an NEC compliant manner with split-phase utility grid input.

If both inputs were floating (inverter, generator, 240V isolation transformer fed from grid), and if instructions directed bonding neutral to ground, then I think it would be NEC compliant.

The following table table from your "manual" says the transformer/ATS can be used for 240V or 208V



The following diagram shows the transformer configuration which produces 120/208Y.
208V is the voltage between any two lines, e.g. L1 and L2.
Your transformer will form a "neutral" half way between L1 and L2 that is anything but neutral.
What is labeled as "N" in the manual's diagram is anything but neutral, for such an application.
It will be 60 Vrms.
Each "line" will be 104Vrms.
(both of those while fed from L1 & L2 of a 120/208V grid; after transferring to your inverter it would be 120/240V split-phase, but floating without neutral/ground bond.)




I only see some NEC compliant ways to use this transformer/ATS, and then with instructions beyond what you have published.

Since we're on this subject is there a reason watts or SS can't work to either import these as split phase or offer them like they are the growatt with a inverter? Why can't we seem to get past the 6KW on the mpp here in the US? How about a new EG4 inverters @ 12kw? And ..at least a 100A pass through while 200A would be ideal.

Two 120V HF inverters (either in two boxes or one) is the low-cost light weight solution to providing 120/240V split-phase.
That saves the cost of aluminum or copper low-frequency windings and the weight of iron core.

Hey @BenFromSignatureSolar, do you offer such a product?
I think that is what you should have for price-sensitive customers.

You do have LF split-phase:


And it looks like 120V HF single-phase, stackable for 120/240V split-phase:


A pair of those would be $1438, 3kW on either 120V output, 6kW at 240V.

I think that's what you should be promoting rather than auto-transformer on output of 240V inverter (for customers with grid input.)
Oh, does that have relay to feed through from grid? Or just a battery charger?

Hedges said:

Two 120V HF inverters (either in two boxes or one) is the low-cost light weight solution to providing 120/240V split-phase.
That saves the cost of aluminum or copper low-frequency windings and the weight of iron core.

Hey @BenFromSignatureSolar, do you offer such a product?
I think that is what you should have for price-sensitive customers.

You do have LF split-phase:

Growatt 12KW Split Phase Off Grid Inverter | SPF 12000KT DVM-US MPV

Signature Solar provides solar panels, off-grid solar systems, grid-tie, and hybrid systems. Quality solar inverters, bifacial solar panels, complete solar kits, solar batteries. Featuring brands such as EG4 Electronics with their solar battery, LifePower4 and EG4 LLifePower4 and EG4 LL

signaturesolar.com

And it looks like 120V HF single-phase, stackable for 120/240V split-phase:

https://signaturesolar.com/content/documents/GROWATT/1519009-specs.pdf

A pair of those would be $1438, 3kW on either 120V output, 6kW at 240V.

I think that's what you should be promoting rather than auto-transformer on output of 240V inverter (for customers with grid input.)
Oh, does that have relay to feed through from grid? Or just a battery charger?

Click to expand...

I mean really if someone was to go that route, we would recommend the EG4 6500. It would be a couple hundred more dollars but the communication with our batteries will be much better. (Well except for the V2 LL battery that came out today. It communicates with Growatt, EG4, Schnieder, Victron, Sol-Ark, and one or two others)

The specs on the 6500 are huge as far as MPPT input goes. That would probably be in line with what you were mentioning.

BenFromSignatureSolar said:

I mean really if someone was to go that route, we would recommend the EG4 6500. It would be a couple hundred more dollars but the communication with our batteries will be much better. (Well except for the V2 LL battery that came out today. It communicates with Growatt, EG4, Schnieder, Victron, Sol-Ark, and one or two others)

The specs on the 6500 are huge as far as MPPT input goes. That would probably be in line with what you were mentioning.

Click to expand...

We'd like to see EG4 at 12/15k output though...just because it's a lower tier inverter doesn't mean they can't keep up.

But..all these MPP clones though are basically the same...meh. MPP does not seem to be interested in upping their game regarding build quality; they seem to have no planes for targeting a higher tier product like deye for example. While I'd defiantly be interested in a EG4 at a much higher wattage output I'd also be enthusiastic if somebody decided to compete with solark at a much more realistic price point. Either work with MPP to up their game and build a much higher quality inverter or give deye a jingle and work with them to build a inverter for you. Personally, I think SS or watts etc.. could figure out a way to import deye inverters and use the anti trust laws against solark. Put it in a different case, paint it a different color and slap a different logo on it...that's what everybody else is doing. While they wont ship to the states you can find a 16k deye on chinababa for $2500. There's got to be a way to get this in our hands split phase hopefully...and keep that price point.

realpinochet said:

We'd like to see EG4 at 12/15k output though...just because it's a lower tier inverter doesn't mean they can't keep up.

But..all these MPP clones though are basically the same...meh. MPP does not seem to be interested in upping their game regarding build quality; they seem to have no planes for targeting a higher tier product like deye for example. While I'd defiantly be interested in a EG4 at a much higher wattage output I'd also be enthusiastic if somebody decided to compete with solark at a much more realistic price point. Either work with MPP to up their game and build a much higher quality inverter or give deye a jingle and work with them to build a inverter for you. Personally, I think SS or watts etc.. could figure out a way to import deye inverters and use the anti trust laws against solark. Put it in a different case, paint it a different color and slap a different logo on it...that's what everybody else is doing. While they wont ship to the states you can find a 16k deye on chinababa for $2500. There's got to be a way to get this in our hands split phase hopefully...and keep that price point.

Click to expand...

The need has been noticed and calculated. There are currently many irons in the fire at SS.

BenFromSignatureSolar said:

The need has been noticed and calculated. There are currently many irons in the fire at SS.

Click to expand...

Just don't leave them too long and let them melt.

BenFromSignatureSolar said:

I mean really if someone was to go that route, we would recommend the EG4 6500. It would be a couple hundred more dollars but the communication with our batteries will be much better. (Well except for the V2 LL battery that came out today. It communicates with Growatt, EG4, Schnieder, Victron, Sol-Ark, and one or two others)

The specs on the 6500 are huge as far as MPPT input goes. That would probably be in line with what you were mentioning.

Click to expand...

6500W 120V, $1250 each, up to 6x wired split-phase or 3 phase.
No transformer needed. Much better than trying to use a 220V inverter and autotransformer in a grid-backup system.
At 40 lbs. each, 4x of these (HF) inverters have (continuous and surge) power slightly above my 4x Sunny Island, but weigh (and cost) barely more than one

realpinochet said:

While they wont ship to the states you can find a 16k deye on chinababa for $2500. There's got to be a way to get this in our hands split phase hopefully...and keep that price point.

Click to expand...

Looks like 2x EG4 6.5kW comes close. 13kW (26kW 5 second surge) for $2500.
Feature set probably differs (especially grid feeding and supporting AC coupling), but for some applications would do the same things.

Hedges said:

Looks like 2x EG4 6.5kW comes close. 13kW (26kW 5 second surge) for $2500.
Feature set probably differs (especially grid feeding and supporting AC coupling), but for some applications would do the same things.

Click to expand...

The quality of the internals and overall build quality is much higher on the deye....the solarks proved this out over time which is why I hope somebody can figure out how to get deye in the USA again. This is just my personal opinions from research and talking to others. Solark is way overrated, they are still a great inverter but overrated and way overpriced. They are not a tier 1 inverter. Tier 1 would be schneider, outback, sma etc. Mpp and growatt are tier 3 inverters. Deye seems to be a fit for a solid tier2 inverter where a gap exist in this field. Solark could have fulfilled this need but they decided to be greedy and charge four times what the inverter is worth. Deye 16k split phase with 200 amp pass through at $2500 would crush it in the diy community for us that are on a budget but still seek quality and long term durability. I'd love to have 4x sma inverters like you...maybe one day.

A couple of new sellers with Sunny Islands on eBay. "New" as in zero feedback.
But the $2500 price and eBay for protection could be attractive.
By the time you buy two and add everything else (including SCC or GT PV) to make a split-phase system, it'll still be way over that $2500 Deye price.
I stopped counting the cost long ago.

If youre off grid why would you ever want split phase ?

.