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

[realpinochet]

I've been seeing this on youtube with david poz and others and am wondering why this is so alluring? Why buy a bunch of 240V only inverters then have to wire in a transformer to provide the neutral when you can buy inverters already putting out split phase power and just parallel them and combine them at the load center? Wouldn't that be a better option for a few reasons. If the isolation transformer you used to split the phase ever goes out you're without power. If you have five units like in this video and the transformer goes out it's over until you get another one. But if you have five units all running split phase natively you can have all but one go out and still have power..reduced but still have power? A few questions, what's the pull towards doing this? And, does this not turn a HF inverter, or in this case five of them, into LF devices? Does this help with the surge capacity issues HF units have without using a transformer? I looked up the transformer he used and it's between 2500 and 3k. Lastly ...would something like this even pass inspection with or without grid connection?

 

[Risky Rob]

Can a 240 Inverter be wired directly into your home circuit panel?

 

[realpinochet]

Can a 240 Inverter be wired directly into your home circuit panel?

That's not what I was asking! I'm saying why go through all that trouble when you can get units with split phase ready to wire in. hope that put more context to it.

 

[timselectric]

Cost is the reason.

 

[realpinochet]

Cost is the reason.

Still new to this but didn't realize 240 units where that much cheaper if that's what your alluding to. I need to compare 240V inverters + a $3k isolation transformer to the cost of a few mpp or growatts with split phase natively. I thought it was a more robust system. I noticed, since you mentioned it, some of the victron invertors @ 240V were a little cheaper. Thanks Tim.

 

[timselectric]

Still new to this but didn't realize 240 units where that much cheaper if that's what your alluding to. I need to compare 240V inverters + a $3k isolation transformer to the cost of a few mpp or growatts with split phase natively. I thought it was a more robust system. I noticed, since you mentioned it, some of the victron invertors @ 240V were a little cheaper. Thanks Tim.

They can be very cost saving, if you can safely work them into your system. .

 

[timselectric]

I chose the Growatt SPF-5000-ES. Because I couldn't find a more affordable way to get 5k inverting power, 6k solar charging, and 4.8k AC charging. With a built-in transfer switch, and stackable, for under a grand.

 

[robby]

It's stems from the Fact that Electricity in China and in most of the World is 240V Single Phase and therefore you can use low cost Inverters that are made for sale in China in the USA if you can convert the power to 120V Split Phase. The upside is that you save a lot of cash on the purchase. The down side is that the quality control on many of the Inverters is not that good, so you have to know which ones to buy. Secondly the Autotransformer is using a lot of power that is essentially wasted as heat and lastly it cannot be Grid Tied as it will not Pass any kind of electrical inspection.

 

[realpinochet]

I chose the Growatt SPF-5000-ES. Because I couldn't find a more affordable way to get 5k inverting power, 6k solar charging, and 4.8k AC charging. With a built-in transfer switch, and stackable, for under a grand.

Are you in the US and if so did you split it with a transformer; if yes did you use a isolation transformer? Did you get it permitted; I don't plan on being off grid nor sell power back but would like grid assist or sbu mode. However I'm wondering about home insurance for a setup like this. I'm curious what would happen if you're using a isolation transformer and loose it for whatever reason. Does the appliances connected just stop working since they are "isolated" from the grids neutral..or does stuff get damaged. If I goes this route I'd use a isolation transformer. You make a great point on why you selected what you did sir.

 

[realpinochet]

It's stems from the Fact that Electricity in China and in most of the World is 240V Single Phase and therefore you can use low cost Inverters that are made for sale in China in the USA if you can convert the power to 120V Split Phase. The upside is that you save a lot of cash on the purchase. The down side is that the quality control on many of the Inverters is not that good, so you have to know which ones to buy. Secondly the Autotransformer is using a lot of power that is essentially wasted as heat and lastly it cannot be Grid Tied as it will not Pass any kind of electrical inspection.

Yep, I'd use a isolation transformer if I choose a path like this and the one that guy used in the video I linked said it was 97% efficient.

 

[timselectric]

Are you in the US and if so did you split it with a transformer; if yes did you use a isolation transformer?

Yes, In the US.
I use an autotransformer.

Did you get it permitted

Nope, it would be hard to pass inspection.

I'm curious what would happen if you're using a isolation transformer and loose it for whatever reason. Does the appliances connected just stop working since they are "isolated" from the grids neutral..or does stuff get damaged. If I goes this route I'd use a isolation transformer. You make a great point on why you selected what you did sir.

An isolation transformer is the safest option.
If it fails, everything just shuts down.

My system is custom built. But, I have the knowledge, background, and skills that are required.
(38 year residential, commercial, industrial, mining, and marine Electrical experience)

 

[realpinochet]

Just curious, do we have a section here or elsewhere with the failure rate of tier 2 inverters AIO or module based? I'd like to see how mpp stands up agains growatt or eg4 etc.

 

[realpinochet]

Yes, In the US.
I use an autotransformer.


Nope, it would be hard to pass inspection.



An isolation transformer is the safest option.
If it fails, everything just shuts down.

When you use a transformer like this, auto or isolation, does it help the surge capacity of a HF system since you're adding a transformer after all?

 

[timselectric]

When you use a transformer like this, auto or isolation, does it help the surge capacity of a HF system since you're adding a transformer after all?

Maybe a little, but nothing worth counting on.

 

[realpinochet]

Was just looking at mpp newer offerings. Wonder if something like this would work? It's 11kw which is more than two of those growatts but about $500 cheaper. Pair a few of these up with a transformer or is there something special about those specific growatts? I'd assume you'd just remove the internal ground screw in these; I'd confirm with mpp first but just curious as I ran across it. Looks like it has dual scc's. What do you look for on inverters to make sure they can do what I believe is called sbu mode..as in I want it to use solar and battery first then use the grid if necessary to power the loads? I don't care nor ever intend on pushing power back to the grid. This unit says.

"Wide AC input range for bypass"

MPP Solar Inc » PIP-MAX SERIES

www.mppsolar.com

https://www.mppsolar.com/v3/catalogs/PIP-MAX.pdf

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[Zwy]

I've been seeing this on youtube with david poz and others and am wondering why this is so alluring? Why buy a bunch of 240V only inverters then have to wire in a transformer to provide the neutral when you can buy inverters already putting out split phase power and just parallel them and combine them at the load center?

The great WHY? question. The reason why is because someone most likely sent Poz the 240V inverters free and he promoted the product.

Whether that is true or not isn't really relevant in some respects. What I've seen time and time again has been "influencers" make a video about a product, then sales increase for that product because the influencer showed how it is done. It doesn't matter if it is safe or if problems occur down the road.

The "latest and greatest new kid on the block" is the EG4. Some videos were made and now everyone wants one, just look at the forum here and the posts that came right after release of the videos.

There are a few of us that see this for what it is, marketing for the most part. Some of it is educational, some is just promotion. As for the 240V Euro inverters with an auto transformer, I had told people there are better choices out there but they had their mind set on the 240V auto transformer system for several reasons, it was in a video so it must be great and 2, it saves them a few hundred bucks. It never really made sense to me, you could buy a LV6048 split phase unit for a few hundred more and have true split phase capability. Will even stated as such in his videos.

But hey, they want what Poz has........... and bought it, then tried to figure out how to use it safely.

 

[realpinochet]

The great WHY? question. The reason why is because someone most likely sent Poz the 240V inverters free and he promoted the product.

Whether that is true or not isn't really relevant in some respects. What I've seen time and time again has been "influencers" make a video about a product, then sales increase for that product because the influencer showed how it is done. It doesn't matter if it is safe or if problems occur down the road.

The "latest and greatest new kid on the block" is the EG4. Some videos were made and now everyone wants one, just look at the forum here and the posts that came right after release of the videos.

There are a few of us that see this for what it is, marketing for the most part. Some of it is educational, some is just promotion. As for the 240V Euro inverters with an auto transformer, I had told people there are better choices out there but they had their mind set on the 240V auto transformer system for several reasons, it was in a video so it must be great and 2, it saves them a few hundred bucks. It never really made sense to me, you could buy a LV6048 split phase unit for a few hundred more and have true split phase capability. Will even stated as such in his videos.

But hey, they want what Poz has........... and bought it, then tried to figure out how to use it safely.

Maybe to some degree but I don't think it has to do with just wanting what some youtuber did...which is why I asked the question I did. Doing some research it seems to make sense under certain circumstances. I've noticed that on some of the tier 2 products split phase offerings like mpp you have to buy more than one unit and stack to get split phase. This forces you go buy two units from day one and if one unit goes down you loose one leg. If you buy a 240 unit you can use one and stack more latter and if one or so goes out you still have full split phase. Another observation seems to be that the higher kw units are mostly 240V and they seem to be a few hundred cheaper as you mentioned and that adds up for some of us. Personally, I'd rather go with split phase right out of the box; I'd also rather get a conext, outback or victron system but that's 3/4x the cost which is another reason I think people weigh their options, research and ask questions. Thanks for your input...you have good points.

 

[OzSolar]

Generally speaking from 30 years of off grid system building experience is that you get 2x the battery charging availability with a 240v system and that's REALLY important for full time off grid installations. We haven't done a system with a autotransformer since the 90's. That's just my 2 cents.

 

[timselectric]

My system, when completed. Will have 40kw output, at least 130kwh storage, and 50kw solar input.
Saving a little here and there, adds up quickly.

 

[realpinochet]

My system, when completed. Will have 40kw output, at least 130kwh storage, and 50kw solar input.
Saving a little here and there, adds up quickly.

Dam 8 of those things..wow.