Hybrid inverters supporting Zero Export to External CT on AC input

[fafrd]

I’ve been searching for / waiting for a 24V hybrid inverter with capability to offset loads on the AC input (grid side) using external CT sensors. This is intended primarily for grid-tied customers with existing AC-coupled solar who are primarily interested in adding a hybrid inverter and a battery for load compensation rather than backup , Luke me (so load compensation on the AC input is a requirement, while support for backup power when the grid gird down is merely a nice-to-have).

Deye / Solark probably set the reference for this capability, but I’m hoping to find a much more budget-friendly option, ideally also supporting a 24VDC.

So I thought II would start this thread to keep a running list of options supporting the Zero Export to External CT Sensor capability as new offerings emerge:

48VDC
Solark / Deye
Outback Skybox
Schneider Conext XW Pro

24VDC
Victron Multiplus II 120x2 & 120 [NOT UL1741, just UL458] (update)

I’m not including Enphase since their AC-coupled battery is not a classic hybrid inverter and it only works within an Enohase-only solution

And I believe the same is more if less true of the Sunny Island (but happy to correct if I am wrong).

This thread is intended to be focused on hybrid inverters that can connect to either/or/both DC-coupled solar as well as AC-coupled solar connected to either the AC input or the AC output with the ability to monitor grid-consumption using external CF sensors and to offset / zero out that consumption by pushing 120VAC or split-phase 240VAC into out into the AC input (US grid only).

There are some new offerings on the cusp of emerging into the US market such as that from Luxpower/Huayu, but I’m going to wait until a few owners in the Forum have reporters on the capability of those inverters before adding them to the list.

 

[BentleyJ]

Did you look at the Schneider SW 4024 it supports AC coupling and Peak Load Shave. I'm using the XW+ model, it uses internal measurements and does not require external CT's. My experience has been that even if Grid Amps is set to 0 during the Peak Load Shave time period there is still a small amount of grid usage but its minimal.

 

[fafrd]

Did you look at the Schneider SW 4024 it supports AC coupling and Peak Load Shave. I'm using the XW+ model, it uses internal measurements and does not require external CT's. My experience has been that even if Grid Amps is set to 0 during the Peak Load Shave time period there is still a small amount of grid usage but its minimal.

From what I’ve understood, the SW will not export AC power Into the AC input (offsets loads onAC output only).

The XW Pro apparently will (using an external energy meter that communicates with it) but it’s more complex to get set up than in on inverters such as Solark with inputs for exterbal CR sensors…

 

[BentleyJ]

You are most likely correct, I didn't fully understand the question in your post.

 

[fafrd]

You are most likely correct, I didn't fully understand the question in your post.

If you think there is anything I can do to improve the clarity of the lead post, appreciate any suggestions.

I stated ‘grid-side’ to hopefully clarify I’m specifically interested in the capability to offset loads on the Main Panel, not only the Critical Loads Panel.

 

[Cheap 4-life]

If you think there is anything I can do to improve the clarity of the lead post, appreciate any suggestions.

I stated ‘grid-side’ to hopefully clarify I’m specifically interested in the capability to offset loads on the Main Panel, not only the Critical Loads Panel.

Very few inverters have bi-directional AC input. Most don’t understand your question becausebthey don’t know it exists. Most think batteries can only be used for AC output to critical loads panel..
that’s the great thing about the GTIL2s, they can use batteries to supply loads in the main panel. Many underestimate the GTIL2s and some partly because they simply don’t understand the major benefit it has to zero the power bill.. not many other inverters can do that. Solis Sofar Deye SolArk Outback XW pro Huayo and maybe even a Growatt, and as you say none of them can use a 24v battery to do so. Probably because of the need for much higher amps with such a low voltage battery.. much more efficient to use a 48v or higher battery.. A lot of the above mentioned inverters are moving to a proprietor higher voltage battery which sucks. . Most users that start dealing with a significant amount of power switch to 48v for the same reasons the mentioned inverters can only do what you want with a 48v battery..

 

[fafrd]

Very few inverters have bi-directional AC input. Most don’t understand your question becausebthey don’t know it exists. Most think batteries can only be used for AC output to critical loads panel..
that’s the great thing about the GTIL2s, they can use batteries to supply loads in the main panel. Many underestimate the GTIL2s and some partly because they simply don’t understand the major benefit it has to zero the power bill.. not many other inverters can do that. Solis Sofar Deye SolArk Outback XW pro Huayo and maybe even a Growatt, and as you say none of them can use a 24v battery to do so. Probably because of the need for much higher amps with such a low voltage battery.. much more efficient to use a 48v or higher battery.. A lot of the above mentioned inverters are moving to a proprietor higher voltage battery which sucks. . Most users that start dealing with a significant amount of power switch to 48v for the same reasons the mentioned inverters can only do what you want with a 48v battery..

If you know of any Growatt inverters supporting ‘Zero-Expor-to-CT’ capability, please let me know and I will add to the list…

 

[Cheap 4-life]

If you know of any Growatt inverters supporting ‘Zero-Expor-to-CT’ capability, please let me know and I will add to the list…

We have had this discussion about growatt and zero export to Ct roughly a year ago. I shared pictures from a growatt manual showing CTs in the parts list. I think it was the SPH inverters. Not sure anymore. Also not sure if a proprietary battery now has to be used with them

Export Limit with Growatt inverters?

I just found this: http://www.ginverter.com/Export-Limitation-Solution.html It suggests that Growatt MIC and MIN Series inverters can be controlled for zero export using a remote CT-sensor-based ‘Growatt Meter’ I’m curious whether we have any members out there successfully using Growatt...

diysolarforum.com

SPF, MIN, and TL-X also do zero export to Ct. but some don’t use batteries

 

[cs1234]

Speaking of the GTIL2's.. has anybody seen this weird one, first time I saw it was today while looking at the GTIL and GTIL2's on amazon.

Tumo-Int 4000w with limiter.

 

[Cheap 4-life]

First time I seen it. Just at a glance it doesn’t look like it can use batteries though.. kinda like the Sun TFL. Which is a high voltage string grid tie inverter with limiter

 

[cs1234]

First time I seen it. Just at a glance it doesn’t look like it can use batteries though.. kinda like the Sun TFL. Which is a high voltage string grid tie inverter with limiter

Yeah, too bad they don't make one a bit smaller that has a lower MPPT input range, then a battery might work. I suppose you could still try a battery with it, but you would have to build up a big non lifepo4 bank as it's hard to find lifepo4 batteries at 100+ volts.

 

[Cheap 4-life]

The inverter doesn’t have settings for a battery low voltage cutoff and reboot inverter battery voltage. That means the bms would have to be used for that. Bms is supposed to be last resort. The inverter is supposed to control the cutoff and reboot.

 

[Ampster]

I’ve been searching for / waiting for a 24V hybrid inverter with capability to offset loads on the AC input (grid side) using CT sensors

Good luck. I just don't think there is much of a market for 24 volt systems. That means low manufacturing volumes when most of the market is 48 volts. If you are going to buy a new inverter, what is preventing you from upgrading to a 48 volt system? Long term that would be the optimal path to more features.

 

[fafrd]

Good luck. I just don't think there is much of a market for 24 volt systems. That means low manufacturing volumes when most of the market is 48 volts.

Agreed. The RV market is the exception and the reason Victron appears to have more 12V and 24V offerings that anyone.

If you are going to buy a new inverter, what is preventing you from upgrading to a 48 volt system? Long term that would be the optimal path to more features.

It’s not a showstopper but severe shading issues have caused me to go the route of a 1S array (of half cut panels).

If I go 2S I’ll lose ~15% of my daily production from that 1S array…

Plus, once you start creeping up in voltage, more and more hybrid inverters and batteries are heading towards higher and higher voltages.

I know 24V, I’m happy with 24V, and if I can find a modest-cost option at 24V supporting the capability I’m looking for, that’s the path of least resistance…

 

[Ampster]

It’s not a showstopper but severe shading issues have caused me to go the route of a 1S array (of half cut panels).

What does that have to do with buying a 48 volt inverter that has the features you want? Your micros should solve the shading issue. AC couple them to a new inverter with AC coupling and export limiting features and you can add solar capacity without tripping up your NEM agreement.
.........

I know 24V, I’m happy with 24V, and if I can find a modest-cost option at 24V supporting the capability I’m looking for, that’s the path of least resistance…

The path of least resistance is what is available in the marketplace at reasonable prices. 48 volts is just 2 X 24 not much more magic there. A whole lot of benefits in terms of less Amps.
A more descriptive title would be, "Hybrid Inverter with export limiting" The load offset is simply physics and how you set up the critical loads panel or wire it to your main panel. Load offset is not going to be a feature described in many inverter specs.

 

[fafrd]

What does that have to do with buying a 48 volt inverter that has the features you want? Your micros should solve the shading issue. AC couple them to a new inverter with AC coupling and export limiting features and you can add solar capacity without tripping up your NEM agreement.
.........

My grid-tied array is AC-coupled and based I Microinverters, but my new ‘backup’ array is DC-coupled and charges my 24V house battery…

It’s the new DC-coupled array that suffers from severe morning shading do zi’ve edified it to be 1S and using half-cut panels to maximums the power output (all unshaded half-panels co tribute full power at Vmp).

With a Vmp of 35-40VDC, that means a 24V battery is as high as I can go without switching to 2S…

The path of least resistance is what is available in the marketplace at reasonable prices. 48 volts is just 2 X 24 not much more magic there. A whole lot of benefits in terms of less Amps.

That’s the way I’ll go if good options at 24V don’t emerge when the time comes… (and the reason I’m including 48V hybrids in the list…),

A more descriptive title would be, "Hybrid Inverter with export limiting" The load offset is simply physics and how you set up the critical loads panel or wire it to your main panel. Load offset is not going to be a feature described in many inverter specs.

Good point. I’ll see if I can edit the title…

 

[Mattb4]

Problem with how many describe things is it leads to confusion. You are either in parallel with a power source or not. Grid parallel means that your inverter has matched AC phase, frequency and voltage. It is like DC parallel when you put two batteries together or a battery and a DC power supply like a SCC. Loads draw from each battery or power supply when that is the case.

So what you are looking for is a solar/battery charging grid tie inverter with limiter. There is one being discussed on the Thread where a fellow wired up his system incorrectly and had fuse holders melt. I believe it is a EAsun model.

 

[fafrd]

I just edited the lead post to add the Victron. Multiplus II 120x2 to the list of inverters confirmed to support Zero Export to CT capability after seeing this outstanding video posted by HighTechLab demonstrating the capability:

 

[fafrd]

Problem with how many describe things is it leads to confusion.

I think ‘Zero Export to CT’ is pretty clear.

You are either in parallel with a power source or not. Grid parallel means that your inverter has matched AC phase, frequency and voltage.

Yes, Zero Export to CT implies that you are grid-tied and outputting energy that is matching phase and frequency with grid (on both L1 and L2).

In addition, ‘Zero Export to CT’ implies you are exporting energy towards the grid but not enough export and power past the CT sensor that is limiting export.

It is like DC parallel when you put two batteries together or a battery and a DC power supply like a SCC. Loads draw from each battery or power supply when that is the case.

The analogy I find more helpful is that if a DC-coupled array charging a battery through an SCC.

As the battery approaches full charge, the MPPT will throttle-back PV power to exactly match constant-voltage battery charge power.

If additional loads draw more DC energy from the battery, the MPPT will draw more power from the solar panels to supply that additional DC load.

Zero Export to CT is similar except that the approach of consumption where the CT is placed approaching Zero Amps plays the role of a battery approaching full charge state in the DC-coupled analogy and the inverters ability to throttle-back input to avoid Export past the CT sensor plays the role of the MPPT in the DC-coupled analogy.

So what you are looking for is a solar/battery charging grid tie inverter with limiter.

No, the solar and the charging are not required. What is required is the ability of a DC-powered (battery and/or SCC) inverter to throttle-back grid-tied power generation to avoid export past an external CT sensor clamped to the same leg.

There is one being discussed on the Thread where a fellow wired up his system incorrectly and had fuse holders melt. I believe it is a EAsun model.

Not understanding how that is relevant, but if you want yo provide a link, I’m happy to have a look…

The Zero Export to CT capability I’m discussing is no different than what any Solark Hybrid inverter can deliver (as well as the Schneider Conext XW Pro).

 

[cs1234]

I just edited the lead post to add the Victron. Multiplus II 120x2 to the list of inverters confirmed to support Zero Export to CT capability after seeing this outstanding video posted by HighTechLab demonstrating the capability:

I don't think the multiplus ii 120x2 has ul listing though, too bad.