Need some help - GTIL SUN inverter limiter wiring

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AndrewH

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Sep 13, 2021
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Hey guys,

New around here but I found a thread from last year talking about some of the wiring for the CT sensors but it didn’t quite answer all of my questions.

I have 3 of the latest generation inverters, 2 - 2000w that will be connecting to 5500w worth of panels and a 1000w that’s connected to my 200ah 48v battery bank powered by 2000w of panels.

I’m not an electrical engineer by any means but I do a fair bit of electrical at my day job (industrial maintenance) so I have a decent level of understanding.

1. Can I use the same 2 CT sensors for 3 outputs? I’ve seen many people do 2 outputs but not 3.

2. How should I wire these? Parallel or Series ? (I’m using the CT sensors that came with the inverters)

3. Can someone post a picture of how they wired theirs together?

4. With two sensors reading both L1/L2, assuming they aren’t balanced, what should the inverter be displaying? Should it be reading the total incoming from both lines or should it read the lower/higher of the two or an average? For instance say L1 is 1000 watts and L2 is 2500 watts, what should I be seeing on the inverter as the read out?

5. I was playing around last night and two would read a negative number and the other would read a positive number, if I flipped sensor 2 would read positive and one would read negative. Are the inverters wired different internally? I know I can swap the wires around and get them all reading positive but then the reading doesn’t match what my Sense power monitor / smart meter says I’m pulling from the grid.

6. Is there any issues having two sets of the CT sensors next to each other on the incoming main? I have my Sense monitor, plus the two for the inverters. Will that cause interference or anything?

That’s all I’ve got for now, I’m just trying to gain more knowledge on how these sensors and inverters work so I can ensure that I don’t backfeed into the grid.

I appreciate any help/information you guys can give me!
 

AndrewH

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Sep 13, 2021
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Cheap 4-life is a moderator over at Solar Grid Tie Inverter with Limiter USA Users https://www.facebook.com/groups/1455824754596738/ he can probably answer your questions.
later floyd
I appreciate the link, didn’t think to look for a specific group on Facebook. I saw there was a few pretty knowledgeable guys here that posted on the thread from last year so hopefully they’ll see this thread and contribute.

Thanks again!
 

Cheap 4-life

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Cheap 4-life

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Cheap 4-life

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1. Yes you can use 2 CTs for as many inverters as you want. I’ve seen 6 inverters all using the same two CTs.
2. Through much discussion here and on the Facebook group, it appears that you can wire the CTs in series or parallel. I wired mine in series and via the iotawatt the inverters are limiting perfectly and my iotawatt shows the amount of power used in a month exactly matches electric company.
3. I’m skipping lol
4.yes the inverter should show the total power the home is using. I don’t trust it. I use my iotawatt power monitor to see what the inverters are producing and what the grid is still supplying
5. You want all of the inverters to be showing positive not negative. Make sure your sense isn’t only reading each leg individually. If it is then it will appear as if one leg is being overfeed and the other underfeed, when in fact that not happening because your homes meter reads your power usage at 240v. The homes meter has one ct in it with both mains going through it in opposite directions.
6. I try to keep distance between the Cts. Don’t know how much that matters
 
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grundholm

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Just pay attention, this sensor measures in mA and not mV - GTIL has a builtin resistor.
 

Wolf

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Sep 25, 2018
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@AndrewH First of welcome to the board. You have come to the right place although we like to talk about batteries more. ;)


I run 4 GTIL1000 2 on L1 and 2 on L2. Now this is a different setup than yours but @Cheap 4-life runs his similar to your proposed manner nevertheless in essence the principal stays the same.
I run each pair of inverters on 1 CT that is paralleled into 2 connectors so each GTIL1000 on let's say L1 gets the same info.
I have found out some of them have the wires reversed on the connector at the GTIL internal input connector. I.e. when I was testing out how to join the CT,s to the GTIL I would connect the CT to 1 GTIL and would get the proper positive reading but connecting the same CT to the 2nd GTIL on the same leg would read negative. A head scratcher at first till I took them apart and found the wires where 180° reversed. I suppose it doesn't matter as if you were only using 1 GTIL you would just turn the CT around. So before you finalize and solder the connections be sure the Inverters are reading positive import from the grid. May be only 4 or 5 watts but needs to be positive.
As far as the CT wiring is concerned parallel or series I don't know but it appears that it doesn't matter too much as the GTIL has a job to do and that is get the reading from the CT down as close to 0 as possible without going into the negative. It's basically a simple feedback loop that analyzes the value of the CT and if high, turns up the volume so to speak, till the CT value drops and tries to maintain that "on the fence walk". WIring the same CT to 2 or 3 GTIL will just split the load between the 2 or 3 as each one of the GTIL will take the load as needed and the others will take up the slack jockeying for position and playing a cat and mouse game albeit certainly not in a frenzy or out of control swings but rather a well mannered give and take, politely giving each of the GTIL a turn when the mood strikes them.
CT distance spacing, if you are going to have more than 1 CT on each leg, is not important as the CT encapsulates the magnetic flux density within the core and really doesn't affect an adjacent one as both of them do the same thing at the same frequency. Any cross talk will be minimal at best and more than likely only noticeable on a oscilloscope as minimal noise. You do want to shield the cables coming from the CT to the GTIL especially if you extend them.
One thing I would do though is to try and balance your L1 and L2 load center as best as possible.
Wolf

20210804_190152.jpg
 
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