CT Placement - How smart is the software?

I am about to purchase, and I’m trying to figure out the best use of CT’s

My electrical setup is a little complicated

I’m thinking of the following. Can you tell me if it seems like a plan?

  • 2 x 200a CT’s in the Main Panel over the wire running into the main breaker, but also looping in the 30a feed from the portable generator inlet. Then the total power to the main panel will always be correct, even in the unlikely event I am using my 30a inlet

  • 2 x 200a CT’s on the 125a garage sub breaker

  • 2 x 100a CT’s after the solar disconnect, BEFORE the line side tap. Or, can this be one CT and just set it as double? I assume I can but I’m not sure

But then is the software smart enough to make a view that is JUST the house? as long as I exclude the garage sub panel from the view? Right now there is no other breakers in the main panel but the 200a feed through lugs, and the 125a breaker.

Another question. Can the 9VAC adapter be plugged into the garage sub? Or does it need to be on the main?


Sure, you could do that. You can create a Script that subtracts the Garage from the Main Panel. But rather than try to combine the Main Breaker and 30A generator cables, why not just put the CTs on the House feed through and make a Script to add the House and Garage to get the total? Seems simpler because of the multiple cables on the Mains, but all the same in the end.

You can use a garage outlet for the VT.

Only 5 Months later and I still have not yet installed, but I decided to go a little overboard, this is what I’m planning to do this weekend or as soon as my second order of CT’s comes in

I realize this might seem like overkill, but if I’m putting monitoring in place, then I figure I want to really monitor everything. Having separate CT’s from the solar, grid, portable generator and main generator means I can push this into InfluxDB/Grafana and have long term history on power from either source, with a very easy way to differentiate. Having a VT on each leg will also alert me to a situation where I have a bad natural and I have a high and low leg.

  • 1 x 100A CT on one leg from the solar disconnect before it gets to the line tap (Doubled)

  • 2 x 200A CT’s on both legs of the wire going into the 200A TS from the meter after the taps for the solar

  • With the above, I can calculate total grid consumption by just subtracting the solar from the total. And I can calculate total power export with the same calculation

  • 2 x 50A CT’s on both legs of the portable generator input

  • 2 x 200A CT’s on both legs from the 27kw Generator to the TS

  • 2 x 200A CT’s on Garage Sub Panel 125a breaker

  • 2 x 200A CT’s on the 200a Feed Through lugs to the House Sub panel

  • A double pole 15 or 20a breaker in the garage sub - 2 hots and a shared neutral going to an outlet with the tab separated on the hot side so I can have a single VT on each leg of the panel to get voltage and frequency measurement

  • Power Inlet at my garage UPS, romex run to box with IotaWatt for UPS backed power for the IotaWatt

Any problems with this proposed setup anyone can see?

1 x 100A CT on one leg from the solar disconnect before it gets to the line tap (Doubled)

Does your solar interconnect have a neutral? (Most likely yes). In that case you will need a CT on each leg due to the possibility of imbalanced load.

I’ll have to check, but I don’t recall seeing one. Its an Enphase combiner box with Enphase IQ7+ Micro Inverters

I’ll have a spare 100a CT, so if there is any question I don’t mind throwing an extra one on anyway

The current generation monitoring has all of one leg going through a single CT, nothing on the other leg. The consumption monitoring has a CT on both legs

It’s pretty normal for solar installations to only use the two line wires, and no neutral. Microinverters are typically tuned to produce 240v, so they’re just all connected line-to-line. In my solar install, the only wires that even go up to the roof are line1, line2 and ground.

There might be a meter or monitoring device that runs on 120v built into the combiner box, which is the only reason I can think of why it might need a neutral. But that device could very easily be designed to run on 240v, eliminating the need for the extra wire. Given how clever Enphase engineers are, I bet this is what they did.

I checked the Enphase Combiner, and there is no neutral. The Envoy runs on 240v on a double pole 10a breaker