New Lux Power LXP-LB-US 12k / GSL-H-12KLV-US with 200A AC Passthrough Current (US Market)

[adamantium]

Are you sure that is how the Sol-Ark inverter works?

GSL has 100A generator input, 200A AC pass through and you can couple any amount you want on the output side of the inverter. That means you can have as much power as you can afford up to 200A on the output side. More than that and you will exceed the 200A pass through back to the grid.

 

[Not Aerosmith]

GSL has 100A generator input, 200A AC pass through and you can couple any amount you want on the output side of the inverter. That means you can have as much power as you can afford up to 200A on the output side. More than that and you will exceed the 200A pass through back to the grid.

You avoid the question about having more power than 50A available when you are AC couple during a power outage..

 

[OutlawSolar]

You avoid the question about having more power than 50A available when you are AC couple during a power outage..
View attachment 118917

Yes, you can have more than 50A combined power of LUX + all grid ties connected.
In my case using Growatt 12Kw off grid to AC couple, my 2 EV chargers can soak up most of 15Kw grid tie inverters.
The total combined power if 12+15Kw.

But the problem arises when the cars being charged are full and the batteries are nearly full too.
The master AC couple inverter needs to tell the other inverters to lower their power or even to shut off.
In my test case using growatt inverter, I had to manually shut them off one by one to load balance.

 

[fromport]

If the frequency shifting works, there will be no need to rely on the headroom on the battery.
LUX inverter will shift the frequency up gradually to tell all connected grid tie inverters to reduce their generated power when the battery is full and grid is not connected (or down). That is why frequency shifting scheme is central to AC coupling. All inverters claiming to have a full AC coupling capability need to have this feature.

Grid tied inverters is another word for current injection into an existing sine wave.
You need to be "ahead" of the sine wave a little and with higher voltage in order to pump the power in.

Now imagine this scenario:

MY AC (3000 watt) is running & fridge/freezer/computers/internet stuff (1000 watt)
Total house load is 4000 watt.
I have 6000 watt panels connected to my LP inverter, I have batteries and they are already 96% full and I have 2000 watt of grid tie inverters hooked up.
8000 watt PV, only 4000 watt load so exporting 4000 watt into the grid.
Grid disappears.
LP takes over and generates microgrid while disconnecting from the grid.
It takes 2000 watt from the 6000 PV panels hooked up and together with 2000 of grid tied inverters keeps everything running.
there is a load of 4000 that is now equally split between LP & grid tied inverter (AC coupled)
Now my thermostat tells my AC it is cold enough and switches off the 3000 watt load.
Rest of the house is only using 1000 watt and the grid tied AC coupled inverters are making 2000 watt.
What happens in the (milli)seconds the 3000 watt load is switched off ?
Where is the 2000 watt from the grid tied inverters going ?
the LP will eventually switch frequency to tell the grid tie inverters to power down.
This is the graph from the LP installation manual:

It will take several seconds before the LP changes freq, and than the grid tied inverters lower their output.
It can not calculate what frequency it will have to change to in order to balance the load with the grid tied inverters.
It will just taper down and adjust, in the mean time the grid tie inverters try to get rid of their power by injecting it into the micro grid from the LP.
If the batteries would be somehow drained to eg 90% the power could be used to charge the batteries, gently find the right frequency and balance things out.
That was the remark I tried to make earlier.

My other hybrid inverter (megarevo) has AC coupled to the generator hookup of the inverter.
That way if it detects the AC coupled input vs the load is out of balance it will open the relay -> grid tied inverters will not see grid any more -> anti-islanding -> stop producing in milliseconds.
Inverter can change frequency to eg 62 hz, close relay, after 300 seconds the grid tie inverters will try and help again , lower frequency to 61.5 and _slowly_ find the balance again.
It is just another way of thinking.
This is (afaik) the same way the SOL-ARK takes care of this.

Long story, I hope I tried to explain it a bit better with the above example.
If not, let me know.

 

[fromport]

Has any one successful AC-coupled a Fronius inverter ? I was told in the early days of AC-coupling, albeit years ago and things have changed quite a bit, that Fronius inverters were notoriously difficult to AC-couple. Enphase micros seem quite happy and straight forward with AC-coupling.

What particular model Fronius are you concerned about ?
I have a primo in use and a galvo as a spare. I don't have one of the IG in working state at the moment.

 

[Wrt83]

I’m wondering if they have considered grid tie ac coupling on the generator side where there is a relay similar to sol-ark. Not being able to dump that output quickly seems dangerous. Gen relay has 100 amps of handling so 24kw… plenty. Yes, you loose the generator, but could add your own manual transfer switch there if needed.

Really thinking about this from the perspective of having 2 way charging on cars for extra battery capacity. Maybe v2g/h is quicker to respond to calls to decrease output or have a different mechanism than feq shifting (that seems like a dirty hack)… something like the upcoming emporia v2x.

 

[fromport]

Can we actually get more power than 50A for whole house use when we are AC couple?

Yes

If we were Sol-Ark and connecting through the generator port, we would definitely be limited to 50A passing through the inverter before connecting to the household demand.

Sol-ark 15k (== same capacity as the LP/GSL we are discussing in this thread) has 19.2kW AC coupling = 80 amps.

GSL is connecting the AC couple power to the UPS port not generator port, which is the same connection for the household power. The household demand could use the AC couple power for the house before its input into the inverter. In my case 15,000/240=62.5A from AC couple. The inverter can still provide 50A from solar panels or batteries. The maximum power would be 62.5A + 50A = 112,5A.
View attachment 118910
This seems like an advantage for GSL over Sol-Ark when AC coupling existing inverters.

Yep but only at noon of a not hot but super bright day.

 

[OutlawSolar]

Grid tied inverters is another word for current injection into an existing sine wave.
You need to be "ahead" of the sine wave a little and with higher voltage in order to pump the power in.

Now imagine this scenario:

MY AC (3000 watt) is running/fridge/freezer/computers/internet stuff
Total house load is 4000 watt.
I have 6000 watt panels connected to my LP inverter, I have batteries and they are already 96% full and I have 2000 watt of grid tie inverters hooked up.
8000 watt PV, only 4000 watt load so exporting 4000 watt into the grid.
Grid disappears.
LP takes over and generates microgrid while disconnecting from the grid.
It takes 2000 watt from the 6000 PV panels hooked up and together with 2000 of grid tied inverters keeps everything running.
there is a load of 4000 that is now equally split between LP & grid tied inverter (AC coupled)
Now my thermostat tells my AC it is cold enough and switches off the 3000 watt load.
Rest of the house is only using 1000 watt and the grid tied AC coupled inverters are making 2000 watt.
What happens in the (milli)seconds the 3000 watt load is switched off ?
Where is the 2000 watt from the grid tied inverters going ?
the LP will eventually switch frequency to tell the grid tie inverters to power down.
This is the graph from the LP installation manual:
View attachment 118926
It will take several seconds before the LP changes freq, and than the grid tied inverters lower their output.
It can not calculate what frequency it will have to change to in order to balance the load with the grid tied inverters.
It will just taper down and adjust, in the mean time the grid tie inverters try to get rid of their power by injecting it into the micro grid from the LP.
If the batteries would be somehow drained to eg 90% the power could be used to charge the batteries, gently find the right frequency and balance things out.
That was the remark I tried to make earlier.

My other hybrid inverter (megarevo) has AC coupled to the generator hookup of the inverter.
That way if it detects the AC coupled input vs the load is out of balance it will open the relay -> grid tied inverters will not see grid any more -> anti-islanding -> stop producing in milliseconds.
Inverter can change frequency to eg 62 hz, close relay, after 300 seconds the grid tie inverters will try and help again , lower frequency to 61.5 and _slowly_ find the balance again.
It is just another way of thinking.
This is (afaik) the same way the SOL-ARK takes care of this.

Long story, I hope I tried to explain it a bit better with the above example.
If not, let me know.

In theory, the above should work fine. The LP would tries to maintain a constant voltage on the UPS port by absorbing excess power generated from grid tied inverters into its batteries.

When the batteries can no longer absorb the excess power, the UPS port voltage will rise and the LP should up shift its frequency to throttle down the grid tied inverter. It's a just a simple feedback loop.

That's in theory, but in practice has anyone see a test result or have tested this feature out to see if LP claim is a vaporware or actually works. I planed to test with out with my setup but had to return the inverter before I could do the test.

If this AC coupling actually works, I can get rid of my generator. As my existing grid tied system can fully charge up the batteries even on a cloudy day.

 

[Not Aerosmith]

i figure it out everything work flawlessly… the Gen port is working properly but i asked GSL if they can make an option the Gen port for ac couple input… firmware were sent me once but im i still waiting on the newer update…

I’m wondering if they have considered grid tie ac coupling on the generator side where there is a relay similar to sol-ark. Na v2x.

GRV0423 has already asked GSL for the ability to AC couple at the generator port. He was expecting a firmware update with this feature. Maybe he can answer your question.

 

[OutlawSolar]

GRV0423 has already asked GSL for the ability to AC couple at the generator port. He was expecting a firmware update with this feature. Maybe he can answer your question.

I hope that LP/GSL considers changing its way of interface with user/installer. So far we have been talking to sale or marketing guys on deeply technical issues. I wish they put us in touch with design team or at least customer support engineer or have one of their technical people come on to this forum.

The more clear answers they can give, the more credibility on the product. So far who knows if this thing actually works with this release? and when it will work? what works, what doesn't work, etc?

 

[fromport]

In theory, the above should work fine. The LP would tries to maintain a constant voltage on the UPS port by absorbing excess power generated from grid tied inverters into its batteries.

in my scenario I told you the batteries are 98% full. when they are that full, they can not absorb hardly anything

When the batteries can no longer absorb the excess power, the UPS port voltage will rise and the LP should up shift its frequency to throttle down the grid tied inverter. It's a just a simple feedback loop.

That's in theory, but in practice has anyone see a test result or have tested this feature out to see if LP claim is a vaporware or actually works. I planed to test with out with my setup but had to return the inverter before I could do the test.

If this AC coupling actually works, I can get rid of my generator. As my existing grid tied system can fully charge up the batteries even on a cloudy day.

1 60 Hz sine wave cycle is 16.7 milliseconds.
How many milliseconds do you think it will take to
a) have the LP adjust it's frequency
b) have the GT inverters take notice of the changed freq and adjust output

We are talking seconds.. where is the power going in the mean time?
It will produce smoke somewhere.
That is why the grid is darn good when it is there. it will never say no to extra power. there is always a place to dump it to.
Not on a local level with a micro grid.

This is my idea:
AC coupling with frequency shifting is great when you have gradual changes of loads or a battery to act as a buffer.
When the amount of AC coupling is the same (or larger) as the hybrid LP inverter in am pretty sure you will run into some very weird effects when you have larger load shifts.

But you are right, who is going to actually test it and make a video of it ?

 

[OutlawSolar]

in my scenario I told you the batteries are 98% full. when they are that full, they can not absorb hardly anything

1 60 Hz sine wave cycle is 16.7 milliseconds.
How many milliseconds do you think it will take to
a) have the LP adjust it's frequency
b) have the GT inverters take notice of the changed freq and adjust output

We are talking seconds.. where is the power going in the mean time?
It will produce smoke somewhere.
That is why the grid is darn good when it is there. it will never say no to extra power. there is always a place to dump it to.
Not on a local level with a micro grid.

This is my idea:
AC coupling with frequency shifting is great when you have gradual changes of loads or a battery to act as a buffer.
When the amount of AC coupling is the same (or larger) as the hybrid LP inverter in am pretty sure you will run into some very weird effects when you have larger load shifts.

But you are right, who is going to actually test it and make a video of it ?

A few seconds or even minutes is fine, my Growatt can easily absorb 12Kw into its battery (I already tested)+ some loads already consume some power.

This feedback loop doesn't need to react fast. The batteries are a good buffer (unless the batteries are very small). it can handle a short term surge ( if implemented correctly).

when that 200Amp passthru relay connected to the grid, LP invert doesn't do AC coupling (all grid tied inverters actually tied to the grid via the passthru relay).

LP inverter does AC coupling when there is no grid and it has to couple the AC output of the grid tied inverters with its UPS output into its batteries. There are not that many inverters that can do this at the moment.
Solark and a few.

Oh BTW, I don't think AC coupling will work well without a battery.

 

[fromport]

A few seconds or even minutes is fine, my Growatt can easily absorb 12Kw into its battery (I already tested)+ some loads already consume some power.

Even when your batteries are > 95% full ?
BMS's limit the charge rate above 95%
Again: in my example the load was 1000 watt, AC coupled inverters were supplying 2000 watt to the hybrid inverter.
Batteries are full.
where does the extra 1000 watt go in MILLISECONDS after the load (ac switches off) is gone?

This feedback loop doesn't need to react fast. The batteries are a good buffer (unless the batteries are very small). it can handle a short term surge ( if implemented correctly).

It _does_ need to respond fast, in milliseconds.
That is what I have been trying to say all this time.
I still don't know why you _think_ that is not the case.

and @Not Aerosmith wants to AC couple 15kW to his GSL.
1741AS does _not_ change in milliseconds the ability to limit the AC coupled inverters

Look at this graph:

from 100% to 10% takes more than a few 60 Hz cycles

Source: https://www.nrel.gov/docs/fy18osti/71453.pdf

 

[Not Aerosmith]

I received some encouraging news tonight without asking for an update:

 

[OutlawSolar]

Even when your batteries are > 95% full ?
BMS's limit the charge rate above 95%
Again: in my example the load was 1000 watt, AC coupled inverters were supplying 2000 watt to the hybrid inverter.
Batteries are full.
where does the extra 1000 watt go in MILLISECONDS after the load (ac switches off) is gone?



It _does_ need to respond fast, in milliseconds.
That is what I have been trying to say all this time.
I still don't know why you _think_ that is not the case.

and @Not Aerosmith wants to AC couple 15kW to his GSL.
1741AS does _not_ change in milliseconds the ability to limit the AC coupled inverters

Look at this graph:
View attachment 118938
from 100% to 10% takes more than a few 60 Hz cycles

Source: https://www.nrel.gov/docs/fy18osti/71453.pdf

That's why I'm interested to see if anyone has any success with this AC coupling and if our smart engineers at LP already put in place a mechanism to not letting AC coupling charges the batteries to full level.
Or better giving us an option of setting the SOC level (% or voltage) where throttling begin.

I just want know more about the AC coupling capability of this inverter so I can safely deploy it.

 

[Not Aerosmith]

If I only AC couple (2) 5KW GT inverters and left the third inverter as a spare, I could connect the 6KW of solar panels to the new 12K hybrid inverter MPPT. GT inverters are designed for maximum production from available solar energy or off. The hybrid inverters may be better able to modulate and match the production from the solar panels with the consumption. I would think between the solar panels and the batteries that the AC couple inverters would normally be off during a power outage.

 

[summit]

What particular model Fronius are you concerned about ?
I have a primo in use and a galvo as a spare. I don't have one of the IG in working state at the moment.

I didn't implement it, was just inquiring of the possibility. It was the Fronius ig3000. Can the Primo AC-coupled ?

 

[summit]

In my case using Growatt 12Kw off grid to AC couple, my 2 EV chargers can soak up most of 15Kw grid tie inverters.
The total combined power if 12+15Kw.

But the problem arises when the cars being charged are full and the batteries are nearly full too.
The master AC couple inverter needs to tell the other inverters to lower their power or even to shut off.
In my test case using growatt inverter, I had to manually shut them off one by one to load balance.

slightly off topic: in your offgrid EV charging setup, are you throttling the EV charge demand ? or just let the Growatt+battery do the buffering ? I'm wondering how it works when there's insufficient juice from PV & battery. Thanks

 

[OutlawSolar]

slightly off topic: in your offgrid EV charging setup, are you throttling the EV charge demand ? or just let the Growatt+battery do the buffering ? I'm wondering how it works when there's insufficient juice from PV & battery. Thanks

No, I don't have a way to tell the charger to lower its power.
I only plan to use it as a way to bleed of excess power during mid day,

 

[adamantium]

You avoid the question about having more power than 50A available when you are AC couple during a power outage..

I just didn't spell it out for you. What I said was you can couple any amount you want on the output side of the inverter. The inverter just provides the grid signal. You must specify how you are AC coupled when you talk about AC coupling. You can be AC-coupled on the input side of the inverter (grid-tied) and you can be AC-coupled on the output side of the inverter (also grid-tied when the grid is on). You can be AC-coupled on the output side when you are running off grid with an inverter only, or when the generator is also running. Its all AC. This means you can have 50A + 200A AC-coupled as long as you are consuming or discarding all of the energy you are producing. You can discard to the grid if you are grid-tied, or you can discard to your battery if you have batteries to charge, or you can discard to something else. You can have 50A + 2,000,000A as long as you can consume or discard the 2,000,050A.

The point here is that the AC-coupled energy is on the output side of the inverter and therefore has nothing to do with the inverter. The energy does not flow through the inverter. So the terminals won't melt, the relays won't fry, the batteries won't explode. The only thing that will happen if you don't consume or discard the excess energy is that the AC voltage will rise to unacceptable levels on the inverter outputs and your house, and once that happens the AC-coupled PV inverters will turn off completely. They are required by law to disconnect from the AC source immediately when the voltage level becomes abnormal. They will then wait for around 5 minutes before they will start sampling the voltage levels again and then turn on if all is right.

The only time you need frequency shifting is when the grid is off (intentional or not) and you don't have a way to discard all excess energy. Unless you are draining your batteries everyday and you have a gigantic battery bank, a power outage is more likely to occur when your batteries are already fully charged. This means that you won't have any place for excess energy to go when you are over producing. As has already been explained by others, this is a problem if the frequency shifting isn't immediate, or the grid-tie inverters don't respond quickly enough, or the feature simply doesn't work yet in the GSL inverter. We currently have no information about how fast the GSL inverter frequency shifting works. Nor do we have any information about how fast your PV inverters respond to frequency shifts. Nor do we have any information about what the GSL inverter does when abnormally high voltages appear on its outputs.

Assuming we never get any answers for any of those questions, a simple solution is to add a diversion load controller and load. This solution has already been mentioned at least twice. They are designed for this exact condition and respond essentially instantaneously to abnormal rises in voltage. That is their purpose and they are relatively inexpensive. So heat some water and if it gets too hot dump some water, or connect to an infinite load like a swimming pool if you have one, or try to boil the ocean or a stream if you are near one, or get a set of outside resistors, heaters, lights, or turbines, or just get a normally-closed SSR that turns off some of your inverters when they are producing too much energy.

A question that I don't believe has been asked yet is what does the GSL inverter do when it is running on generator power and PV power is AC-coupled to the output side of the inverter? Since their is a 100A relay for the generator does the excess power back feed the generator and burn it up? Does the GSL inverter detect energy other than from the generator and close the generator relay and switch to inverter power from the batteries to keep the PV inverters running? Does it leave the generator running or shut it down? Does the GSL inverter detect abnormal voltage and shut everything down? Does the GSL inverter somehow isolate the generator power from the AC-coupled solar inverters? If so how would they isolate generator energy from AC-coupled PV energy and still be AC-coupled? No matter what the answer is, you will still need a diversion load controller and a load if you want all of the parts to continue running.

Now you see why I didn't spell it out before.