OpenEnergyMonitor Community

Monitoring of two buildings with solar in North America

NOT a problem, Dan. Sometimes “life” just gets in the way. :wink:
It looks like you’ve got plenty of room above the main lugs for CTs with a 3/4 inch wire window.

Typically, that family of CTs is the voltage output type. (333 mV) not the preferred choice
for use with OEM hardware. Variants with current output are available, you just have to do a little
searching. Here’s an example:

They’re not outrageously expensive, but they’re not low cost like the SCT-013 and SCT-016.
Cost is usually 40 to 50 bucks each.

Yep, like I said, a work in progress. There used to be just 100A service with smaller service entrance cables (2AWG). I upgraded to 200A service with new panel and larger mains (4/0) to reduce voltage drop over the 160ft/50M run to meet code for grid tie in the future. This was part of a major expansion of the building that also relocated the panel adjacent to where the solar equipment is housed. I am currently working on extending metal conduit for all the circuits.

Looks good!

I have made a some good progress on the wiring in the shop, and am able to get back to the monitoring projects. I have been looking at possible CT sources for the 4/0 AL URD conductors, and have found an affordable option on eBay from US sellers. There are several listings for these SunPower PVS5 monitoring kits with a pair of Jiangyin XH-SCT-0750-100 CT’s for $20-$30 USD, including shipping. e.g.:
Sunpower PVS5 Outdoor Metering Consumption Kit 522398 Jiangyin XH-SCT-0750-100
@Robert.Wall mentions in Help with whole house power monitoring (200amp/USA) that one should replace the SMT burden resistors on an emonPi with 33Ω versions for similarly spec’ed CTs. I assume I should need to do a similar mod to emonTX shield (honestly I haven’t looked at the boards yet). I would like to order the CT’s early this week, and start diving into the boards later on.

Unfortunately, those CTs are the voltage output type.
What you want is an unburdened CT that puts out current vice a voltage.
IOW, for what you’re wanting to do, it’d be a waste of $$$ to order them. :frowning_face:

Here’s an example of what you want:

and here’s another:

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The plus side of a voltage-output c.t. is that the output voltage is accurately calibrated by the manufacturer. The minus side of a voltage-output c.t. is that the output voltage is accurately calibrated by the manufacturer and you can’t change it (upwards) to suit your individual circumstances. You can of course add a second parallel burden to reduce the voltage, but that’s hardly ever necessary.

In your case, you need to choose the burden resistor so that at the maximum current you’re interested in, the burden develops no more than 1.6 V. (I’m talking rms values of course.) The equivalent voltage for the emonTx and emonPi is 1.1 V rms, because the ADCs have different voltage input ranges.

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Thank @Bill.Thomson and @Robert.Wall, as always your expert feedback is appreciated! I was questioning that in the back of my mind, am glad I posted this before proceeding. Will update with status later this week.

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