Hedges
I See Electromagnetic Fields!
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A different next step would be to see what happens to excess power when battery is fully charged.
If you had an SoC based switch, you could kick GT PV offline before then.
Will it work? Supplementing off grid inverter/battery with on grid PV inverter in one system.
- Thread starter apctjb
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A different next step would be to see what happens to excess power when battery is fully charged.
If you had an SoC based switch, you could kick GT PV offline before then.
timselectric
If I can do it, you can do it.
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I have always been against using an off grid AIO (not capable of AC coupling) , as a grid source for micro inverters. Because they aren't capable of dealing with a forced input to their output. (Presumed smoke release)
But I have been thinking about it a lot. Because I have some micro inverters. And want to include them into my system. I have several locations that one or two more panels could be placed.
I think (no science behind it) that it could be possible with a stackable AIO. Because they are used to seeing a parallel source on their output. (Usually controlled through communication)
I'm assuming that they have provisions for loss of communication. Maybe, they will just shutdown, if the parallel source overwhelms the output.
But maybe as long as it's not overwhelming, it just continues to run. This could explain why you are seeing charging from the parallel source (micro inverters).
This all seems plausible and promising.
But I have been thinking about it a lot. Because I have some micro inverters. And want to include them into my system. I have several locations that one or two more panels could be placed.
I think (no science behind it) that it could be possible with a stackable AIO. Because they are used to seeing a parallel source on their output. (Usually controlled through communication)
I'm assuming that they have provisions for loss of communication. Maybe, they will just shutdown, if the parallel source overwhelms the output.
But maybe as long as it's not overwhelming, it just continues to run. This could explain why you are seeing charging from the parallel source (micro inverters).
This all seems plausible and promising.
I saw a video by Ben Nelson at 300mpg.org, he's using an iMiev Chademo to power his AIO as well as AC-couping his M215s. I can't locate right now but will link upon finding, where he mentioned that his micros simply shut-down; probably with Vac rising about upper limit.
I can bench test it easy enough by lowering the float voltage.
300mpg.org
I can bench test it easy enough by lowering the float voltage.
CHAdeMO V2H - Home Power Backup - 300MPG.org
Ever since modern, commercially produced electric cars starting coming out in 2011, there has been talk of using them as power backups. There have been a hand-full of products out there, but with limited availability, prototype only, or non-U.S. power specs. So, I thought I’d try my own.On my...
300mpg.org
There are AC coupled AIO, like the BLUEPOWER one posted before
timselectric
If I can do it, you can do it.
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Yes, I'm aware.
But this discussion is about off grid AIO's.
I'm very interested in trying this. There must be a way to get it working.
The cheapest AC coupled inverters that I could find are the Bluepower branded Sungold IP6048, MPP LVX6048 WP, Rich Solar inverters, which all seem to be the same and around $1500 for the 6k version. The specs and size are exactly the same and advertised as AC coupling. I couldn't find any off grid models that are marketed as AC coupled, but you could just use this series as off grid. No reason why you can't.
Anyone here has experience with any of these inverters?
The cheapest AC coupled inverters that I could find are the Bluepower branded Sungold IP6048, MPP LVX6048 WP, Rich Solar inverters, which all seem to be the same and around $1500 for the 6k version. The specs and size are exactly the same and advertised as AC coupling. I couldn't find any off grid models that are marketed as AC coupled, but you could just use this series as off grid. No reason why you can't.
Anyone here has experience with any of these inverters?
zanydroid
Solar Wizard
At some point it might be easier to crowdfund 1 battery and 1 inverter to somebody who has a bunch of microinverters, appropriately set up workshop, and time to do testing.
(I don't have time to do the testing, DER Solar and ncsolarelectric are busy testing other microinverter combinations; I don't know if GXMNow has time for that, it's more work to set up an AIO than it is to add a new microinverter string onto an existing XW)
(I don't have time to do the testing, DER Solar and ncsolarelectric are busy testing other microinverter combinations; I don't know if GXMNow has time for that, it's more work to set up an AIO than it is to add a new microinverter string onto an existing XW)
timselectric
If I can do it, you can do it.
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I will be testing it at some point. Maybe next year, if I have the time.
zanydroid
Solar Wizard
Thanks for sharing but there are plenty of threads here already on the XW in AC coupling mode.
What stood out to you about this video?
What stood out to you about this video?
If you have the right inverter, it's possible to do
Of course, ac coupling is possible. Just not with the cheap inverters you are looking at.
timselectric
If I can do it, you can do it.
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That's the point we have been trying to make.
Pick one that is capable of AC coupling.
zanydroid
Solar Wizard
I don’t know if I mentioned it on this thread yet, but one theory I came up with recently is that microinverters are probably not going to respond that quickly to a load drop. They don’t need to do that when pushing to grid. Sometimes people talk as if they are a perfect constant power source that will push 300W each no matter what even if the load disappears.
What is the default behavior of a PSW if the load disappears? Probably not a bad surge.
As well all inverters need to be able to handle some back kick from inductive loads.
So the AIO may not immediately blow up, but it needs to do something before the microinverter reacts.
I still don’t think an arbitrary AIO is going to work, but I’m guessing a random LF one might not be that hard for manufacturer to modify for basic AC coupling. Like try to counteract the slow voltage increase from the microinverter with increased charging.
timselectric
If I can do it, you can do it.
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I don't know a lot about micro inverters. But it's my understanding that they react to voltage increases. I believe that's one of the control parameters.
So, when the load decreases (or disappears) the voltage will increase. And they should "self control". The problem is that an AIO that's not designed to deal with that. Doesn't have the ability to survive that brief time of voltage increase (on their output). Before the micro inverters react to it.
So, one of two things happen. They shut down and throw an error. Or they release the magic smoke.
These are just my thoughts on how they work. I could be way off.
zanydroid
Solar Wizard
There are a couple different reactions here.
They do react to voltage and frequency changes from the grid (this is a 1741SA behavior), but there is a deadzone before anything happens, and the frequency control is used by AC coupled inverters to throttle or stop the inverters gracefully.
Another one is increasing voltage / other PSW parameters to push out the maximum amount of power towards the "grid". Which in this case is the grid forming inverter. More concrete example. Suppose grid tie inverter is outputting 600W, and it's all consumed by a space heater. Space heater is clicked off. With some mental models of grid tie inverter it will immediately start raising the voltage until either they send 600W into the AIO (which would be terrible if it's not configured in charger mode) or the voltage lets out the smoke.
If the AIO does not react at all, either the GTI will shut off when the voltage rises enough, or smoke comes out.
What I'm saying here is that the AIO just has to have enough CPU to react faster than the GTI will adjust, and be programmed to react in the first place. If the GTI are fairly slow and forgiving then it's easier for one of this sketchy/cheap AIO companies to figure it out. If the GTI is a twitchy wild stallion then it would be a lot harder to implement AC coupling.
Will an AIO inverter's PSW output surge the voltage if a load cuts off?
timselectric
If I can do it, you can do it.
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I believe that we are saying the same thing.
zanydroid
Solar Wizard
A generator does not have any of the odd extra behavior of a GTI.
Generators are already designed to feed local loads. Automatically adjusting the output and tolerating rapid changes in demand. As well, AIOs have been explicitly designed to handle generators for a long time. Generators do not need to sense AC to turn on.
GTI are designed with the grid as a load. The grid is a simple low impedance load that doesn't change much. GTI are interactive AC sources so they have to sense & qualify AC before turning on.
THought experiment. What happens if you plug a Generator into a Chargeverter? What happens if you plug a single GTI into a Chargeverter?
In Generator case, charging will start. No problem.
In the GTI case, nothing will happen.
Generators are already designed to feed local loads. Automatically adjusting the output and tolerating rapid changes in demand. As well, AIOs have been explicitly designed to handle generators for a long time. Generators do not need to sense AC to turn on.
GTI are designed with the grid as a load. The grid is a simple low impedance load that doesn't change much. GTI are interactive AC sources so they have to sense & qualify AC before turning on.
THought experiment. What happens if you plug a Generator into a Chargeverter? What happens if you plug a single GTI into a Chargeverter?
In Generator case, charging will start. No problem.
In the GTI case, nothing will happen.
zanydroid
Solar Wizard
I'd say either pay up or find a thread where multiple people have gotten a less common inverter to work. And have extensively shared their test setup - how much DC solar, how much AC coupled, what brand, how many. If it's too rich for your blood, hibernate for 6 months and see what is available in June next year.
Even with a $$$ inverter I would not buy without finding a thread like that. And I would go into it with a pretty healthy expectation that I might lose my money. Unless the thread is from someone I know really well on the forum.
This may be overly pessimistic, but it comes from the sob stories of jacked up IQ8 AC coupling into premium inverters, in the hands of very technically sophisticated users.
Even with a $$$ inverter I would not buy without finding a thread like that. And I would go into it with a pretty healthy expectation that I might lose my money. Unless the thread is from someone I know really well on the forum.
This may be overly pessimistic, but it comes from the sob stories of jacked up IQ8 AC coupling into premium inverters, in the hands of very technically sophisticated users.
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