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LionKing

Do Axperts support Grid-tie/Sharing?

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Helping out my uncle with picking an solar inverter, his municipality does Not allow net-metering/sending electricity back to the grid. However, he wants to mix-match electricity e.g. If the load is 4KW and 5KW solar is only making 2KW then remaining load (2KW) should come from the grid AND Batteries should only be used when Grid is down (i.e. last option to tap).

My understanding is that this happens in a Grid-Tie inverter But axperts are classifieds as Off-Grid and there is no information regarding grid-tie on voltronic's website as well. I contacted a local installer, who did my install as well and is quite informative, but he said that Axpert do support Grid-sharing.

Does anyone know whether this is true or not?

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25 minutes ago, LionKing said:

he wants to mix-match electricity e.g. If the load is 4KW and 5KW solar is only making 2KW then remaining load (2KW) should come from the grid AND Batteries should only be used when Grid is down

The only real way to do this with an Axpert is with an Axpert King. There are actual grid tie models; the Infini series of hybrid (grid-tie with battery) inverter-chargers are made by the same manufacturer, but the quality seems lower with the Infini series.

There are some Kings in SA (e.g. see this post), but they don't seem to be common as yet. You may have to buy from Ebay. @Gnome , where did you get yours from?

Edit: I should have added that you can get quite close to the desired behaviour with the more common Axpert models, but they can't actually combine utility and solar power for supplying loads (can combine for charging the battery, however).

Edited by Coulomb

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8 minutes ago, Coulomb said:

There are actual grid tie models; the Infini series of hybrid (grid-tie with battery) inverter-chargers are made by the same manufacturer, but the quality seems lower with the Infini series.

You mean Axpert is lower quality than Infini or Infini is lower quality?

Actually, I'm in Pakistan and I got mine from the Installer - who got it from a reseller Omega Power Usa (www.omegapowerusa.com) and the website doesn't work. Hoping I don't run into any warranty issues. 😔

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16 minutes ago, LionKing said:

You mean Axpert is lower quality than Infini or Infini is lower quality?

Infini lower quality than Axpert. When they work, the Infinis seem to be good, but they seem to have a tendency to blow up expensive parts.

See for example this post.

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Yea, that's what I recall from my last year's research that it was Infini Super and I think also V models that had component/board issues. Don't recall any issues with Infini PLUS.

Coming back to the original question, I looked at Voltronic's website but don't see anything specific about Grid-tie support in Axpert King manual. Looks like Hybrid inverters basically do what I'm looking for and that's the Infini line.

Whats the difference between regular Infini and Infini V?

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6 minutes ago, LionKing said:

I looked at Voltronic's website but don't see anything specific about Grid-tie support in Axpert King manual.

Oops. I forgot to mention that the King doesn't achieve grid and solar blending at the AC level (it's not grid tied at all), but at the DC level. There is an AC to DC converter for the grid, a DC to DC converter for the solar, these DC sources are combined, and the loads are driven by the DC to AC converter (the actual inverter).

I also neglected to mention that if the load is higher than the inverter can handle on its own, then the inverter has to bypass, just like a regular Axpert, and no grid with solar blending takes place.

Quote

Whats the difference between regular Infini and Infini V?

I don't know if the V stands for Value line as it does for Axperts, but I know that all the Infini V models have 145 V (presumably buck stage, outputting to the battery) solar charge controllers.

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22 minutes ago, Coulomb said:

Oops. I forgot to mention that the King doesn't achieve grid and solar blending at the AC level (it's not grid tied at all), but at the DC level. There is an AC to DC converter for the grid, a DC to DC converter for the solar, these DC sources are combined, and the loads are driven by the DC to AC converter (the actual inverter).

I just spoke with my installer and he's saying that he has VM installed in his own home and it definitely gets excess energy from Grid, instead of switching completely to Grid - when PV array can't provide enough power for the current load. 

22 minutes ago, Coulomb said:

I also neglected to mention that if the load is higher than the inverter can handle on its own, then the inverter has to bypass, just like a regular Axpert, and no grid with solar blending takes place.

I assume you're refering to Rated power of the inverter, instead of PV array not making enough to run the current load?

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2 minutes ago, LionKing said:

I assume you're referring to Rated power of the inverter, instead of PV array not making enough to run the current load?

Yes. In non-bypass modes, all load power goes through the inverter.

3 minutes ago, LionKing said:

I just spoke with my installer and he's saying that he has VM installed in his own home and it definitely gets excess energy from Grid, instead of switching completely to Grid - when PV array can't provide enough power for the current load.

As in an Axpert VM III or Axpert VM II? It's my understanding that the battery has to supply the difference, and the grid can't charge the battery while solar is providing part of the load. I'll readily admit I'm not familiar with the VM models.

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On 2019/05/06 at 5:07 AM, LionKing said:

... municipality does Not allow net-metering/sending electricity back to the grid...

... he wants to mix-match electricity ...

 

Hi @LionKing

if sending electricity back to the grid is prohibited and you want to blend PV power with the grid power at the same time, then there's only one correct way to do it:
It's AC-DC-AC conversion, namely Axpert King, aka PIP-5048MK. Just like @Coulomb suggested. A quite affordable unit, that can handle up to 5kVA loads where for example 3kVA are comming from PV, while 2kVA are being pulled from the grid. If 5kVA unit is not enough for the house, this model allows you to parallel more units into a single powerfull system.

image.thumb.png.05410194544b009c1c7eb2554c0ad34c.png

Specsheet: http://www.mppsolar.com/v3/catalogs/PIP-MK.pdf
User manual: http://www.mppsolar.com/manual/PIP-MK (PF1.0)/PIP-MK manual-20181106.pdf

 

A solution using On-Grid, Grid-Tie or Hybrid inverter is also possible, but it WILL send a small amount of electricity back to the grid every day. By design, there's no way how to prevent this behavior. No matter what brand of Inverter you use, no matter what additional electronics you will add. Sooner or later, the electric company will find-out.

In my country, some guys tried even super-expensive Studer Hybrid Inverter (Switzerland based company) which cost up to 5000 EUR a piece. And even these machines are sending a few watts back to the grid every day. Some added the intelligent dump load controllers, which are consuming excess spikes of PV power, but it's not perfect either. Luckily, local electric company is not issuing penalties....yet.

Edited by Youda

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20 hours ago, LionKing said:

I just spoke with my installer and he's saying that he has VM installed in his own home and it definitely gets excess energy from Grid, instead of switching completely to Grid - when PV array can't provide enough power for the current load. 

I assume you're refering to Rated power of the inverter, instead of PV array not making enough to run the current load?

With the standard VM model, that's impossible.

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On 2019/05/07 at 4:49 PM, Youda said:

With the standard VM model, that's impossible.

I'm not so sure now.

I argued here that Axpert MKS II (PIP-5048MG) can blend AC-in and solar power. The LCD diagram seems to indicate that the blending happens at the AC level, not DC, although the diagram on a small LC Display might not have room to be technically accurate.

This is from a PIP-GK (Axpert VM III) manual:

1064505240_VMIIIblending.png.b0dd3ff76ef9c3820c0e03921d4e7fd4.png

In 2 of the three sub-modes of line mode, there are two arrows pointing to the load. That seems like AC blending to me. That seems to suggest to me that all the PIP/Axpert models with the ~450 V SCCs are capable of feeding the grid, despite claiming off-grid status and not having official anti-islanding firmware that is certified by testing laboratories. Of course, I could be misreading the manuals.

I agree with your comments, @Youda, that the only way to prevent accidental push of power into the grid is with an AC-DC-AC conversion setup, as in the PIP-5048MK / Axpert King.

[ Edit: "Axpert VM II" -> "Axpert MKS II" ]

Edited by Coulomb

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In fact, I believe that this is how the PIP-5048MG / Axpert MKS IIs and PIP-5048GKs operate:

922533389_Possible450Vblockdiagram.png.a62e5c542c0e5cc784d380b98937f1fc.png

 

When PV and AC-in blending is happening, the two switches would be closed (the inverter having synchronised with AC-in first, obviously), and the two right hand converters are bi-directional and could operate in either direction, depending on the instantaneous power values of the available PV and load.

The PIP/Axpert models with the 145 V SCCs have a buck DC-DC connecting to the battery, instead of a boost DC-DC connecting to the ~400 V DC bus. I suppose it would be possible for these to blend PV and AC-in power, but then PV power would be going through thee converters to get to the load. Well, really four converters, since the battery DC-DC is atually two converters with a high frequency transformer between them. So that would be somewhat inefficient.

Once again, all this is speculation on my part, based on the LCD diagrams in the manuals, and one customer report (a few posts above).

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Another diagram to incorporate all (most?) of the Axpert models:

1713930436_Presumedblockdiagram.png.f6e1b92ab22e8e59b8dad450861c6ccf.png

The King would not close both switches at once, since it doesn't do AC blending at all. It would only close the upper switch (opening the lower one first?) when in Bypass/ECO mode. In battery or line modes only the lower switch would be closed (note that the King's line mode is different to the others' line mode).

It's possible that the King also has a dedicated DC-AC converter that converts AC-in directly to battery voltage, since that's what the LCD diagrams imply.

Once more: this is all speculation on my part.

Edited by Coulomb
Added "only the lower switch would be closed"; added power flow arows to diagram

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3 hours ago, Coulomb said:

 

1656466008_Presumedblockdiagram.png.429d7832fb608546a717a1a714d9b5b8.png

 

This is a good summary of the logical layout of many inverters. Goodwe for example... high voltage in, boost up to high voltage DC rail, buck/boost down to the battery.

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Sorry to hijack the thread, but the images are very helpful and raised a question for me. 

 

I have a King. Under what circumstances does it just run Utility straight to the load (ie bypass?) And can I force it into this mode?

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7 hours ago, miles said:

I have a King. Under what circumstances does it just run Utility straight to the load (ie bypass?) And can I force it into this mode?

I would think that this is all in the manual (e.g. https://www.mppsolar.com/manual/PIP-MK (PF1.0)/ ) . My understanding is that utility connects directly to the load when either or both of these applies:

  • the load exceeds that which the inverter can supply, i.e. rated power, or up to twice rated power for a very short time
  • setting 10 ("Operation logic") is set to ECO, or to AUt if the utility frequency is not stable

Both of these are predicated on setting 23 "Bypass function" allowing bypassing.

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Hmm, now that's interesting...

Do I get it right, that when ECO mode is enabled, the MK will bypass the Grid directly to the Load, while at the same time sending the PV energy to the Load too? So it's Grid+PV mixing?

Historically, all the Axperts we're marketed as Off-Grid inverters, but now it looks like these boxes have some hybrid capabilities...🤨

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35 minutes ago, Youda said:

Historically, all the Axperts we're marketed as Off-Grid inverters, but now it looks like these boxes have some hybrid capabilities...🤨

Exactly. Aeroxes (seems that these are made by Voltronic Power) actually have an export enable setting (setting 08, Solar Energy feeding to grid configuration). These seem to be exclusively made for Inverex in Pakistan.

One of the Axpert clones, the Must PH1800 Plus series, seem to explicitly allow export as well. These seem to be based very heavily on Voltronic Power, even the block diagram in the service manual is very similar to one in one of the Voltronic Power Axpert manuals.

So it seems that many Axperts are perfectly capable of pushing power into the grid, and some models seem to be doing it, and two derivatives are making it explicit.

I'd say that means that when a large load comes off say a PIP-5048MG / Axpert MKS II, when blending grid and PV power, there could well be a small, unintended export of power. I'm actually surprised not to have heard reports of meters in South African tripping out.

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15 minutes ago, Coulomb said:

I'm actually surprised not to have heard reports of meters in South African tripping out.

Exactly! I'm surprised too!

But maybe that not many users are running their Axperts in ECO mode while having a prepaid (tripp-able) meter installed at the same time? Hmm 🤔

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I don't have a prepaid meter, but I do have a smart meter which I'm told is 99% of the way there in terms of equipment for me to switch to prepaid (which I intend to do once my billing dispute is resolved). 

I've run my King inverters in Eco mode and seen reported via ICC negative grid watts, which implies I'm feeding back. But my meter hasn't tripped. 

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Posted (edited)
On 2019/05/07 at 8:47 AM, Youda said:

Hi @LionKing

if sending electricity back to the grid is prohibited and you want to blend PV power with the grid power at the same time, then there's only one correct way to do it:
It's AC-DC-AC conversion, namely Axpert King, aka PIP-5048MK. Just like @Coulomb suggested. A quite affordable unit, that can handle up to 5kVA loads where for example 3kVA are comming from PV, while 2kVA are being pulled from the grid. If 5kVA unit is not enough for the house, this model allows you to parallel more units into a single powerfull system.

image.thumb.png.05410194544b009c1c7eb2554c0ad34c.png

Specsheet: http://www.mppsolar.com/v3/catalogs/PIP-MK.pdf
User manual: http://www.mppsolar.com/manual/PIP-MK (PF1.0)/PIP-MK manual-20181106.pdf

 

A solution using On-Grid, Grid-Tie or Hybrid inverter is also possible, but it WILL send a small amount of electricity back to the grid every day. By design, there's no way how to prevent this behavior. No matter what brand of Inverter you use, no matter what additional electronics you will add. Sooner or later, the electric company will find-out.

In my country, some guys tried even super-expensive Studer Hybrid Inverter (Switzerland based company) which cost up to 5000 EUR a piece. And even these machines are sending a few watts back to the grid every day. Some added the intelligent dump load controllers, which are consuming excess spikes of PV power, but it's not perfect either. Luckily, local electric company is not issuing penalties....yet.

Good day sir

I will be grateful if you can help me, i have 2x king 5kw inverters the same as specs and picture above, i want to install 30x 330W Ja solar panels (15 on each MPPT) but without Batteries will add Batteries later, they do have a 20kva backup gene already installed, what I need to know is, is this Inverter Gird tie capable, if i set setting 1 to SUB? i also see that setting 5 (battery setting) have a "SOL" Setting is that for a type of battery? like the the "pyl" setting for Pylon or is it for "Solar loud"  

I will really appreciate if You can assist 

Thank you  

Edited by Jurgens

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Hi @Jurgens

For a shame, Axpert King Inverter is not grid-tie capable and does not support running without batteries.
Luckily, when Axpert King is configured in the SUB mode, it's possible to run it with just a small battery, and it will work too. For example a 3kWh of lithium for the start.


Speaking of battery-less operation, it is supported on these models, specsheets attached:

  • Axpert VMIII
  • PIP5048MG
  • PIP 5048GK

But keep in mind, that battery-less operation is supported only for a single inverter. When running 2 or more inverters in parallel, it's not supported and may kill your inverter.

PIP-MG specsheet.pdf Axpert_VM_III specsheet.pdf PIP-GK specsheet.pdf

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