I’ve been measuring some of our power usage for over nine years. I started with an Efergy system that used Current Transformers (CT) and reported the usage to a central internet server from which I could pull detailed reports. I had gradually expanded this system to measure most of our larger power users and several circuits. The advantage to these Efergy monitors was that they were battery powered and the batteries lasted a long time. The graphs were useful and the data could easily be downloaded into a spreadsheet.
Unfortunately the Efergy system ceased access to data on December 31, 2025! So all of my devices became obsolete. I had been switching over to the Emporia Vue system and started with version 2 early last year. I installed a 16 CT unit in the garage power box. This is the original service box but it now operates as a sub panel due to the solar install. This older system had plugs that fit into 16 receptacles in the main unit. I have more than 16 circuits so I picked the most essential data readings. The new Emporia Vue 3 has small plugs that are removable so the wires can be shortened. That eliminates the rats nest of wires that need to be wound and don’t fit well into the service box.
I added another system but only with 8 CT’s to finish the circuits in this box. Both units need to be attached to two circuit breakers that are stacked in order to power them. Also each unit has a neutral connection. For the main service box outside I added another Vue 3 unit but could purchase one without CT’s as I had enough left over to measure all the circuits. The 200 Amp CT’s can even be used as the 50 Amp CT’s just by changing the plugs on the wires. I am using the replugged CT’s to measure the incoming main solar roof power. The newer 20 amps of solar is also being measured.
I have not yet shortened all the wires as it’s still in a beta mode. I’m not sure I understand the instructions for measuring the solar input. I think that at this point the main solar is only recording what is not used first by the Powerwall. The Powerwall backup batteries are charged first with excess solar that the house is not using. In the evening when the Time of Use increased cost kick in, we get our power from the Powerwalls. I don’t have access to the these wires so I can only use the Tesla figures to estimate the remaining power that goes through this box. Some instructions say to point both CT’s toward the breaker but some say that to measure 220 one CT should be pointed away. I’ve tried both. I am also getting a negative output to grid and zero power imported from grid. Even without the Powerwall charge, the Emporia figures are far from those reported by Tesla. Sooner or later I will get it figured out. The company is based in Colorado and the support team is very knowledgeable and helpful.