Can I measure DC PV input through Iotawatt

I have 2 x 200 amp service (one panel is “critical loads” and the other panel is “noncritical”). I have Iotawatt CTs on the 240v of both panels. I also have 40amp back feed Solaredge AC coupled photovoltaic solar into one of the two panels – the noncritical loads. Everything is working fine. Iotawatt calculates everything beautifully.

However, I just installed Solark 15k hybrid inverter as a backup to one of the 200 amp panels (critical loads panel). I am planning to bring 6kw DV PV input into the Solark 15k. The Solark 15k inverts the DC to AC and then sends that to the critical loads panel. Hence, the Iotawatt CTs in the critical loads panel cannot tell that some of the energy is coming from the DC that has been inverted to AC. Similarly,the Solark15k has only one pair of CTs that I have to place on the 240V service entrance cable before it goes into the Solark15k and only thus interprets energy draw into the critical loads panel. I called Solark, and they do not have a solution to add another set of CTs and then to sum them.

One idea I had was to take one of the smaller CTs and put it on the DC photovoltaic wires. Maybe I could read the amperage (like a clamp meter in DC mode) and then estimate the amount of wattage that the inverter is making? I could then calculate more accurately?

Just read a little more about this. Seems like I need a hall effect sensor for DC rather than a current transformer. Maybe I can buy something that can measure the amperage with a 2.5mm jack like what is needed for the iotawatt? @overeasy?

IoTaWatt inputs measure 0-50mA with a burden, or 0-1V rms without a burden. If you van express the DC current in those terms, it’s electrically possible to bring in the data. Then you would need to kludge a generic input to calibrate to your sensor. You might investigate if there is an existing 4-20mA sensor for DC current as that is an older standard sensor standard.

This is not anything I would consider doing as DIY is one of the main reasons for going open source.

So it is possible, but it doesn’t seem easy :slight_smile: and definitely not overeasy.

I wonder if anybody could point me in the right direction.

I found this in diysolarforum

Not clear what you are trying to learn, but why don’t you just put CTs on the Solark wires to the panel. That would give you information on the power that is coming from solar. You won’t know the efficiency, but it might be enough.

That is brilliant! I can just subtract what is going into the Solark15k inverter from the meter from the actual draw from the two legs of the main from the critical loads panel, and the difference is the production by the DC photovoltaic (minus the consumption by the inverter itself and its inefficiency).

@overeasy I purchased two extra large CTs for the extra panel. Can I get two more large CTs for 200 amps?

Just checked the shop. It looks like you are back up and running and selling?! I thought iotawatt had closed. I am happy that it is up and running.

It is a great product