What's the reason behind using 240V inverters with transformers when they have split phase ones?

[timselectric]

What a drama queen...

This debate and bashing has been going on for well over a year now. Exactly how many transformers have you heard failed during that time?

I know far more stories from friends/family where they lost neutral from a branch falling on overhead power lines or similar. The risk is near zero.

Not to mention, with a few tweaks to the setup, damage from losing neutral is totally avoidable.

I'm also loving everyone's price comparison to the EG4, which has been around - how long?? A few months?? Give me a break. I've had my SPF5000's for over a year now before all these new lower cost 120v inverters came out. Regardless of that fact, knowing what I know today, I think I'd still lean toward the SPF5000.

Same here. I still haven't seen a better priced option, with the same functionality.

 

[copec]

$0.18/w (used panels) $9,000
40kw inverter (Amazon) $6,800
Batteries (agree with you) $16,000
$25,680
49% savings is worth it to me.

You might want to check out Sandi Electric

I was aware of them from Jack Rickard on YT before, but didn’t know any DIY individuals that used them until I stumbled this guy a couple of weeks ago on YT:

 

[timselectric]

You might want to check out Sandi Electric

I was aware of them from Jack Rickard on YT before, but didn’t know any DIY individuals that used them until I stumbled this guy a couple of weeks ago on YT:

Yeah, those are very interesting. I have been following his videos, since the first one. I'm thinking of using one of these to add an EV to my storage capacity.

 

[ncsolarelectric]

Aside from a transformer failure you could have multiple 240V units fail and still have split phase power. Not possible with the way mpp and others do this at the moment unless you want to by four units. That's all I was saying. You're right though the transformer is the weak point so I guess double up on those..some are. And, I'd assume capacity is a concern regardless what system you choose with inverter failure.

As a point of failure, the transformer, if you buy a name brand like Square D or Sola and size it properly. It has the lowest probability of failure out of everything in the system. It is literally copper/aluminum and iron. No semiconductors or switches to blow. If the enclosure doesn't rust away and rodents get inside, transformers can last for 30 years and longer.
I prefer a system with a split-phase "Isolation" transformer because then I can have a true N-G bond at my sub-panel, regardless of what the inverters are doing on the primary. If I drive it with two EG4 inverters, it doesn't matter if I configure them in parallel at 120V or in series as 120/240V, the current between them will be balanced, with full available power on either 120V leg. It's a much better design IMO, but hey, I only designed and manufactured transformers from 1988-2002, what do I know.

 

[realpinochet]

This is what you posted,

Not possible with the way mpp and others do this at the moment unless you want to by four units.

Which was not correct. You were referring to split phase operation where pairs of inverters are used for split phase operation at that time and context.


This is what you posted,

" The main issue was loosing the auto transformer and as such the neutral but then having the ground loop from the grid present itself."

If you lose the neutral on the autotransformer, it will send 240V on the 120V circuits. Now you say isolation transformer because you know you were incorrect.

As it seems you are being evasive once someone points out when you are incorrect, I will no longer continue the discussion. It becomes a waste of time.

I stated very early on in this thread that I found that a isolation transformer is the way to accomplish this correctly. You seem to not like it when people don't agree with you and like to be rude.

 

[realpinochet]

As a point of failure, the transformer, if you buy a name brand like Square D or Sola and size it properly. It has the lowest probability of failure out of everything in the system. It is literally copper/aluminum and iron. No semiconductors or switches to blow. If the enclosure doesn't rust away and rodents get inside, transformers can last for 30 years and longer.
I prefer a system with a split-phase "Isolation" transformer because then I can have a true N-G bond at my sub-panel, regardless of what the inverters are doing on the primary. If I drive it with two EG4 inverters, it doesn't matter if I configure them in parallel at 120V or in series as 120/240V, the current between them will be balanced, with full available power on either 120V leg. It's a much better design IMO, but hey, I only designed and manufactured transformers from 1988-2002, what do I know.

I agree, I'm saying it might pay to have two transformers in case one fails. You're way of doing this with the N/G bond at the sub panel is from my understanding why the isolation transformer is the way to achieve this properly. To isolate from the grid side.

 

[Seven30]

This is what I'm addressing, your comment is claiming that using 2 of the LV6548/EG4 inverters in split phase operation where one inverter goes down, there would not be any power. This isn't true, the settings can be changed in the functioning inverter and 120V would be available in half the panel.


If the neutral goes open, you will feed 240V out on the 120V circuits; I guess some people like new appliances........

Heres some points Ive noticed in this thread so far.
> 220v inverters are more efficient at load than 120v (lower current loss)
>Auto transformers are kind of dangerous but seem to be efficient.
>Isolation transformer is safe
>Isolation transformer is much larger for same VA
>Transformers have parasitic drain on inverter output

But, if your starting from scratch why not source 220v euro appliances and use a tiny 120v inverter for misc loads.

 

[Zwy]

I stated very early on in this thread that I found that a isolation transformer is the way to accomplish this correctly.

You seem to not like it when people don't agree with you and like to be rude.

Certainly not, but will comment if an incorrect statement is made.

Some don't like hearing the facts if it doesn't agree with their misconceptions. I can't help them with that.

 

[Seven30]

As a point of failure, the transformer, if you buy a name brand like Square D or Sola and size it properly. It has the lowest probability of failure out of everything in the system. It is literally copper/aluminum and iron. No semiconductors or switches to blow. If the enclosure doesn't rust away and rodents get inside, transformers can last for 30 years and longer.
I prefer a system with a split-phase "Isolation" transformer because then I can have a true N-G bond at my sub-panel, regardless of what the inverters are doing on the primary. If I drive it with two EG4 inverters, it doesn't matter if I configure them in parallel at 120V or in series as 120/240V, the current between them will be balanced, with full available power on either 120V leg. It's a much better design IMO, but hey, I only designed and manufactured transformers from 1988-2002, what do I know.

Can you comment on the idle/parasitic draw transformers place on the inverter? Do some designs have lower idle draw than others?

 

[ncsolarelectric]

Can you comment on the idle/parasitic draw transformers place on the inverter? Do some designs have lower idle draw than others?

All transformers have what are called Core Losses. This is the power dissipated by alternating the magnetic polarization of the core at 60Hz. It is typically less than 1% of the rating of the transformer if well designed with high-quality materials. There are lower quality magnetic materials that have higher core losses. There is a wide range of materials, efficiencies, and price-points for designers to choose from. They don't publish that information.
Inverters without a transformer are going to be more efficient, but they are also going to have less stored energy to delivery to loads like motors, pumps, AC units, etc. The transformer inductance stores energy providing a larger surge capacity than an equally sized inverter without a transformer. That's why AIMS Power can handle 3X surge and the MPP & Growatt type inverters can barely handle 2X surge.
Your choice is, do you need the surge capability and convenience of having a transformer to isolate the loads? Or do you need the longest possible run time with a limited battery capacity, requiring the highest inverter efficiency. There is no "best of both worlds" scenario, IMO.

 

[Quattrohead]

Toroidal Transformers are more efficient than traditional transformers but both are way more reliable than any semi-conductor !!!!

 

[Seven30]

All transformers have what are called Core Losses. This is the power dissipated by alternating the magnetic polarization of the core at 60Hz. It is typically less than 1% of the rating of the transformer if well designed with high-quality materials. There are lower quality magnetic materials that have higher core losses. There is a wide range of materials, efficiencies, and price-points for designers to choose from. They don't publish that information.
Inverters without a transformer are going to be more efficient, but they are also going to have less stored energy to delivery to loads like motors, pumps, AC units, etc. The transformer inductance stores energy providing a larger surge capacity than an equally sized inverter without a transformer. That's why AIMS Power can handle 3X surge and the MPP & Growatt type inverters can barely handle 2X surge.
Your choice is, do you need the surge capability and convenience of having a transformer to isolate the loads? Or do you need the longest possible run time with a limited battery capacity, requiring the highest inverter efficiency. There is no "best of both worlds" scenario, IMO.

I'm thinking if high current loads like AC, coffee pot, microwave are 220V euro the 120v transformer can be fairly small reducing the "core losses". Obviously the transformer needs to be protected by a suitable breaker like all loads.

More questions. Do the 220V euro inverters float the input/ouput? In otherwords if split phase grid 220v centertap/neutral is effectively connected to chassis would it matter to the inverter?

 

[realpinochet]

Certainly not, but will comment if an incorrect statement is made.

Some don't like hearing the facts if it doesn't agree with their misconceptions. I can't help them with that.

I've seen your comments / interactions on this forums with others and there's a pattern..you're compelled to be insulting and condescending when there's no reason to act that way. Please move past any future post of mine!

 

[ncsolarelectric]

I'm thinking if high current loads like AC, coffee pot, microwave are 220V euro the 120v transformer can be fairly small reducing the "core losses". Obviously the transformer needs to be protected by a suitable breaker like all loads.

More questions. Do the 220V euro inverters float the input/ouput? In otherwords if split phase grid 220v centertap/neutral is effectively connected to chassis would it matter to the inverter?

European inverters have a grounded 220V system. It is equivalent to L2 being grounded. It's not split-phase, so if you connect split-phase transformer, it will short half the output.

 

[John Frum]

I've seen your comments / interactions on this forums with others and there's a pattern..you're compelled to be insulting and condescending when there's no reason to act that way.

Please point out the insult in this thread.
It might help me with my own interactions.
There are 93 posts so I might have missed it.

 

[Seven30]

European inverters have a grounded 220V system. It is equivalent to L2 being grounded. It's not split-phase, so if you connect split-phase transformer, it will short half the output.

Ah ok. I was hoping that L2 ground was selectable.

 

[ncsolarelectric]

Ah ok. I was hoping that L2 ground was selectable.

That I don't know for certain. If the ground connection can be removed, AND the chassis is isolated from the output, then it could work. But... will it void the warranty? Is it possible with a particular inverter? These, I do not know. It will not be UL Listed, that's for certain.

 

[realpinochet]

Please point out the insult in this thread.
It might help me with my own interactions.
There are 93 posts so I might have missed it.

Please point out the insult in this thread.
It might help me with my own interactions.
There are 93 posts so I might have missed it.

Post 55

"For those that are looking for a system to actually run something? Duh!

This is about comparing the capacity of various split phase inverter setups. We don't care about your puny system."

Post 68

"If the neutral goes open, you will feed 240V out on the 120V circuits; I guess some people like new appliances........"

Even after I tried to re claify I was talking again about 240V system and that I had come to the conclusion that a isolation transformer was the way to go ,even if I got a model number wrong, he choose to be who he is. If you want to make a point you generally don't throw a insult in at the end as it negates everything you said in the beginning.

 

[Struc]

Ah ok. I was hoping that L2 ground was selectable.

If you buy the Signature Solar version of the SPF5000ES (US) inverter, it has been modified by the factory to not have the L2 / Ground bond. This has been well documented here.

If you buy a random one from China or eBay, all bets are off. More than likely you will get one that has a relay that connects ground to L2 depending on the mode of the inverter.

 

[Quattrohead]

That poster gets called out because some posts are not correct technically.
We do have to remember that this is an international forum and the rest of the world does not have the weird split phase system.
It took me years to wrap my head around it and now with DIY solar and importing cheap but 240v inverters, the whole mess is exacerbated.