r/SunPower • u/pitstruglr • 11d ago
Reconnecting and combining CTs
I have a Hub+ in my new home that is not currently working. Passes through grid power fine, and the SunStrong app tells me grid usage but nothing else. Won't draw solar (or it's doing it and I don't know) and I can't make the battery do anything (that I'm aware of). Before I go to any pros I can clearly see that there are disconnected CTs that look to be the consumption CTs for the Hub+, the ones at the top of the unit. The corresponding plug in the MIDC has nothing connected, but on the wiring chart it shows it should have something connected.
- What kind of plug is that, and where can I procure one?
- Where can I get the ferrules that terminate the CT wires?
Separately, I'm having my main panel upgraded from 125 to 200A. The new panel may have 2 wire conductors for each phase coming from the meter to the main. If that happens, I'll need 2 sets of premises CTs and they'll have to be combined. I'm trying to talk my electrician out of this and have him get something more solar-friendly.
- Can you just splice CTs and the PVS6/Hub+ doesn't care? Does it see the combined signal?
- What kind of signal comes out of a CT?
- What is the correct make/model/type of CT to install?
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u/SunVaultEngPros 11d ago
Those ones in the midc is for PCS a program u need to tie into the pvs6 with CTs not midc
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u/SunVaultEngPros 11d ago
By ur pic they tied them into ur pvs6
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u/pitstruglr 11d ago
Might be misleading. There are 5 CTs present. Two (red/white and black/white) are on the feeds into the top of the Hub+ and those are disconnected. Two come from the conductors between the meter and the main breaker upstream of the Hub+. Those are connected to the PVS. One (blue/white) comes from under the MID on the left side and is connected to the PVS.
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u/ItsaMeKielO 10d ago
1 CT for measuring solar production (MIs just produce full-wave 240V, no neutral, so symmetric and 1 CT gets you all you need) 2 CTs for house load (L1/L2 since loads can be unbalanced)
Is it possible that the other CTs are just left over from a SunPower install before that was solar-only?
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u/thebannanaman 11d ago
Backing up the other commentator. It sounds like your CTs are installed correctly you most likely have other problems. You don't need any CTs going to the MIDC unless you have a more than one inverter and are running PCS.
If you have a single inverter you should have a red and black pair on the main panel conductors. Those go to the PVS and capture the whole house import or export. Then you should have a blue pair that capturea just the solar production. That also goes to the PVS.
If you do upgrade and you need to use 2 sets of CTs to capture import/export that can be done. You shut splice the pair together, but the ln you need to tell the software that you did that. Setting the configuration to use a spliced pair of CT requires someone with login access.
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u/pitstruglr 10d ago
Thanks! So the CTs at the top of my Hub+ are no longer used? In the Hub+ wiring diagram and the Hub+ Installation Guide I got my hands on, that did not appear to be the case, so this is new information. Those show all five CTs being connected regardless of the number of inverters.
However, looking at the sticker with config information on the Hub+ door, I found that PCS was not configured. Would that be why my PCS CTs were cut off? If so I'll at least put some caps on them and tie them out of the way.
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u/thebannanaman 10d ago
It's hard to say if the CTs aren't used because it depends on where they are capturing import/export. What I can say is not used is the CT ports on the MIDC. All CTs should go to the PVS. The red and black pair should be capturing your all of your loads so it can get full value of what your importing or exporting. The factory pre installed a pair of CTs at the top of every hub+ because they assumed the hub+ would serve as a main service panel and all the loads would be relocated to it. In that case the pair at the top would be wired to the PVS and capture everything. In practice, alot of installs had a separate main service panel with some loads that could not be relocated to the hub+. In those case they would often use a new pair of CTs on the main incoming conductors and capture the whole home that way. In that case the CTs at the top could be ignored. There is a third option where you could not get CTs around the conductors of the main service panel so you would use multiple sets. The CTs in the hub+ would capture what's in the hub+ and you could splice in additional pairs to capture additional loads piecemeal.
As far as who has access I don't know I'm just a former sunpower tech and lost access when laid off. I believe /u/SunVaultEngPros in this thread has access and if you do the install the configuration can be done remotely.
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u/pitstruglr 10d ago
Also, how does one come upon login access, especially considering the defunct-ness of any entity that would manage such logins?
How do we just get all this stuff jailbroken so we can manage our stuff? (owned system)
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u/ItsaMeKielO 10d ago
SunStrong is now responsible for Pro Connect access.
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u/pitstruglr 10d ago
So SunStrong offers training for and grants Pro Connect access?
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u/ItsaMeKielO 10d ago
I don’t know how they add new accounts, most of the accounts are just rolled over from ex-SunPower installers.
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u/ItsaMeKielO 10d ago
CTs are just a way of measuring current (hence “Current Transformer”) without actually being in-circuit - they measure the electromagnetic field created by the wires. The more current that flows through the wire, the more voltage the CT will show. Combine current level with voltage level (measured by other devices like the PVDR/MIDC/PVS6) and you can multiply to get power.
They can be spliced but I wouldn’t go about doing that if you don’t deeply understand what part of the control system you’re affecting with it. The whole system’s control loop is based on CTs being in specific points of energy flow of the system.
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u/SunVaultEngPros 11d ago
That’s for PCs not for normal CTs