Thinking of buying - what to buy?

Hello all,

We recently moved into a larger house and even in the larger house our electricity bill recently doubled so I want to try and figure out what behaviors to change. I have a few questions I was hoping the knowledgeable folks here could answer before I went on and bought stuff.

  1. Can I connect both the reference transformer and the USB power source to a power strip (the same power strip) since I have a plug point shortage near the panel?

  2. My panel looks like this:

    I’m planning to connect the mains clamps to the lines marked in red. I am guessing that will consume 2 of 14 channels? The blue lines are the solar panels coming via a line side tap.

  3. I also want to monitor how much my panels are generating. My understanding is that I have to attach 50A CTs to the solar input here:

    And do I need 2 CTs - one for each wire?

  4. For breakers with 2 wires coming out of them, do I connect 2 CTs - one for each wire? See this:

    Since that is a 60A breaker, what CT do I even use?

  5. Whats the best tool to use for just plotting and seeing daily breakdowns of certain channels?



You may find it a bit tight there. The 25mm clamps might work. It’s also OK to put them down the bottom where the mains come in.

You will need only one 50A CT placed on either of the solar cables.

Please read over this documentation about CTs:

and this about North American split-phase power service:

IMO the included Graph+ is the easiest and best tool to analyze daily usage data. You can create comparative graphics and save them for easy reference daily.

Love your emoji

OMG… I totally just realized I could do this. I have two clamps measuring the connection to my solar sub panel right now, and i can re-purpose one of them to read something else. I just checked my graphs too to verify they read the same values/have the same curves. Thanks!

Tracing some of these neutrals will be a fun exercise for the split phase circuits but I think I get it.
Pure 240 = single ct on single wire with correct polarity.
240/120 split = single ct with opposite double wire or 2 cts with correct polarities.

Are the clampy CTs for the main just better in every way? Seems so.

Thank you, I enjoy my profile avatar as well.

It seems like you operate from NH. I’m just a few miles south of the border in MA.

Not quite, they cost a few bucks more.

It’s free shipping in the US so no advantage, but I am from Mass and lived and worked near Lowell for many years. Massachusetts is tied with California as the second largest IoTaWatt consumer, not really far behind the leading Florida.

Since I’m doing the end of year recap, Australia is head and shoulders ahead of the rest of the world in IoTaWatt deployment, being also one of the most developed PV countries.

Ordered and shipping. Pretty quick.

How many months of data is stored locally on device? Can I upgrade that somehow?

More than ten years.

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Do I need to turn the mains off every time I clamp something?

Do I need to remove the piece of tape in the clampy 200A CT?

Be aware that turning off the mains, if they are inside the load-center, does not de energize everything. There is risk of serious injury or death. If you don’t have knowledge or experience working inside a live load-center, please find someone who does or hire an electrician. I’m sure you understand that I can’t recommend you install theCTs.

Ah yes.

I have worked with high voltage circuits but many years ago. I still have my lineman gloves and can safely work my way around the box. I should have been clearer with my question - will the iotawatt box be ok if it’s live while I move a CT around or connect it?

Yes, you can connect and disconnect CTs and reconfigure the inputs while the IoTaWatt is running.

And do I remove the piece of tape in the clampy CTs?

Yes. Simple remove that as it is a protective piece keeping the connection with the magnets smooth completing the loop.

why is the current equal on both solar incoming lines? (is this also true for line side taps?)

It’s a two wire connection, so it is a single circuit. A fundamental principle is that current in a circuit is constant.

Don’t know what you mean by line side taps. If you are in North America with split-phase power, you may find this interesting:

Sorry if I caused confusion, let me give some supporting information. I’ve got two string inverters with their own 30A and 40A circuits.

I’ve also got two separate 20A circuits which have micro inverters on each, so a total of four solar-related circuits.

I’ve got those four circuits on a single sub panel which I’m monitoring. I call that my “overall solar” production.

Previously, I was using two CTs to monitor the sub panel mains. But after reading this thread, I checked the values on those two CTs and noticed they were exactly the same amperage/wattage, so I removed one and repurposed it, and in the UI I checked the “double” checkbox for the remaining one. I also removed references to the second one in my Outputs to influxdb and outputs for IoTaWatt reporting.

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