Sol-Ark 12K-2P CT Clamp Reading Low, Winding Ratio Setting Doesn't Work?

[johhen]

Hi all,

First off, I know I'm stepping into uncharted territory with this one.

Does the Sol-Ark 12K-2P Winding Ratio actually work?

Problem: My Sol-Ark 12K-2P is under-reading my CT clamps around my mains. I tested this by running my EV charger at ~4.6kW as a load. When set to Limited Power to Home, it gets the Line-HM down to ~25W on each leg (I have Zero Export Power set to 50W), but the meter reports 70W consumption (so, 50W vs 70W). When set to Limited Power to Load, which is more revealing, Grid HM showed ~1.8kW on each leg, so 3.6kW total, shy of the 4.6Kw.

I'm not running factory CT's (see below). I'm running YHDC SCT4333QL 300A 100mA (3000:1 winding) CT's, extended via 23AWG Cat 6 (each pair in the Cat6 is wirenutted to one wire from one CT).

I have the Sol-Ark set to 3000:1 CT winding, but changing this from 2000:1 to 3000:1 did not change the reading, nor did changing it back. I power cycled the inverter (power button off, then all breakers off, then reverse). I presumed changing the winding value would correspondingly change the Grid HM value, given the winding is directly correlated to the amperage. Having a 3000:1 CT running at 2000:1 reading should give ~67% reading, which is _close_ but not exact (I was getting between 70% and 80% of expected).

Details:

My home is fed by a 320A service, which feeds two 200A subpanels right next to eachother in the basement and one 100A subpanel in the garage. One is critical loads - it's been intercepted into the Sol-Ark - and it's really light, like <3000W always. The other is, let's say, luxury loads. These are the Washer/Dryer, AC, etc. Big fatty loads. The last is a garage subpanel - nowhere near the first two - serves a car charger mostly. The service entrance meter/main combo is outside.

I've got a Sol-Ark 12K-2P running for a few months now. Up until today, I've just had the included CT's right around the grid inputs to the inverter. I had it set to limited power to load, and all was dandy. Today, I finished the install of two CT's around all the panel feeders in the main panel - past the breakers, two 4/0 and a 2 AWG inside each CT. Barely enough room to make it work and still close the panel cover. The CT's run on two pairs (blue/bluewhite for white, green/greenwhite for black) etc of a 23AWG Cat6, which runs, I'd guess, 60 feet to the Sol-Ark. The wires are spliced in a junction box outside the main panel with wire nuts. In parallel, rungs another Cat6 for the e-stop button.

Thoughts:
1. Bad CTs.
2. Bad wire, bad wirenut connection, who knows.
3. Cat6 isn't shielded, and its longer than Sol-Ark recommends. Though it is less than people here have said they have had success with. Also, sol-ark manual says to use one-pair per lead (as mentioned above) but forum says to use one pair per-ct.
4. Sol-Ark not respecting winding setting

Solutions?
1. Switch wire nuts to Wago 3 position lever nuts.
2. Sol-Ark 600A CTs (I do not think will fit in my panel)
3. Parallel smaller CTs from Sol-Ark? I've read this might work, might not, but Sol-Ark doesn't recommend it.
4. Temporarily disable the 300A CT, and put a single 100A CT on the luxury-loads panel, at the main, over the same Cat6, try to narrow stuff down.
5. Ignore that it doesn't match? Since it zeros to 50W (70W actual), it seems to do the job, it just looks whack when it goes back to charging from grid, and shows 6000W pulling from grid, and 8000W going into the battery. Wheres the magic 2000W coming from?

 

[robby]

Yes the CT winding ratios work.
I suspect that the cable is not working properly. Reason could be length or the quality of the wire, bends in the cable, proximity of other power sources, Pairs used etc.
Try the same setup with the CT using the shorter OEM cable and clamped through to a separate set of 240Vac wires with a known wattage load on it that you can check. Something like the wires going to the Hot Water heater which you can first measure with a clamp meter and then adjust CT Ratio in the Sol-Ark to display the same reading.

Once you got the Ratio right then put it back on the mains and test again. If it's still off then you know it's a wiring issue and redo wiring as needed. If you cannot get it right during the test then I suspect the CT itself is the issue.

Edit: I would only do this with no PV and just the needed load running.

 

[SunDave]

Wouldn't hurt to call Sol-Ark support just about the fact that your ratio change on the unit doesn't seem to affect things. If they can do something about that, then problem solved. Since you said it did not change the reading, I would start there personally.

 

[robby]

Wouldn't hurt to call Sol-Ark support just about the fact that your ratio change on the unit doesn't seem to affect things. If they can do something about that, then problem solved. Since you said it did not change the reading, I would start there personally.

I think he already did.
I suspect that an unsupported CT and cable is going to make it a very short phone call.
His system was working properly before he changed the CT.

 

[SunDave]

That could be the case Robby. You know more Sol-Ark than I do. I just have one 15k.

Just looked at the manual, says do not change CT ratio unless authorized as it could void warranty. Just a heads up!

 

[johhen]

Yeah - properly, but not supporting whole home loads.

I saw that warning. I called them, they said they only support it in commercial settings. Didn’t have any idea why the ratio change didn’t do anything.

I shoulda tested the CTs right next to the inverter. It’ll be a bitch and a half to get them off and move them and back.

 

[SunDave]

How high of loads are you running when getting 75-80% numbers? There are notes in some CT paperwork about a single Sol-Ark only reading up to 80amps on a pair of CTs.

 

[johhen]

How high of loads are you running when getting 75-80% numbers? There are notes in some CT paperwork about a single Sol-Ark only reading up to 80amps on a pair of CTs.

Total was less than 10kW.

 

[robby]

That could be the case Robby. You know more Sol-Ark than I do. I just have one 15k.

Just looked at the manual, says do not change CT ratio unless authorized as it could void warranty. Just a heads up!

I had actually talked to them when I changed mine to get a more accurate reading.
I suspect that you could do damage if the Inverter is running with a high load and the settings are moved so far out that it makes the Inverter back feed or do something else, it's probably not worth the risk.

 

[LydMekk]

Normal factory setting 2000:1.
And yeah, no need to fiddle with it ^^.

 

[johhen]

How should Grid HM and Grid LD relate when the CT is on the incoming grid line only, and the inverter is in Limited to Load?

Is it expected that the LD is slightly higher than the HM?

I reconfigured it with just the stock CTs around the feeder to the solark, but still over the Cat6 and in the meter main 60 feet away. Set the Ratio back to 2000

Two example picture sets. I changed the battery target % between them to alternate between discharging and charging.

 

[SunDave]

I'll look on my unit when the sun is down and the loads are not negative.

Your inverter uses some power to run and covert DC to AC, so that comes from somewhere. The difference % wise could look larger due to very small loads.