How to position CT clamps correctly so solar does not interfere with EV charger.

[rwdl1984]

We recently had a solar panel system put it in. The solar batteries were delayed and put in after, at which point it became clear that the CT clamp for the solar system was positioned on the wrong cable. The inverter was reading the power generated by the solar system and including it in the house load, causing the batteries to discharge rapidly etc etc.

The solar company (finally) came back and moved the CT clamp to live 1 between the fuse and meter. This sorted out the issue with the inverter and batteries. Sadly, it has caused issues with our existing EV charger. The EV charger ramps up to around 5.5 kW then cuts out. The electrician from the solar company positioned the solar CT clamp right above the EV CT on live 1. He mentioned briefly at the time that they might interfere with one another.

I'm posting this now because the solar company has gone AWOL and are refusing to come back to fix things. Perhaps there is a simple fix here, without me having to convince a new company to and fix this? Does anyone know the correct position for the solar CT clamp that won't cause the EV charger to cut-out?

I have already tried moving the solar CT clamp further up the cable away from the EV clamp (as suggested in other posts), but this has not made a difference. Please see the attached image. The blue circle at top right shows where the solar CT clamp was positioned originally by the company, but this resulted in incorrect power readings on the inverter. The two CT clamps are together on live 1 now, the EV one is the one below.

Any suggestions would be much appreciated!

 

[Deleted account]

I was going to sayEasy fix. One can be positioned after meter, but the hendley block takes two feeds out.

where do the two feeds go? one is the main board what is the other. Could it be separate board for pv or car charger?

if the solar pv is wired directly into the main board add one clamp to the main boards feed tail after the meter.

 

[timhoward]

I think we need a simple system diagram. Basically - is the solar wired what I call the old way, straight into the main board, or does the solar have it's own consumer unit?

(Finally be careful of that hole in the side of the consumer unit, you should get that plugged)

 

[Electro-tech]

Can you please purchase a rubber grommet for the side of the C/Unit. Just an observation.

 

[rwdl1984]

I was going to sayEasy fix. One can be positioned after meter, but the hendley block takes two feeds out.

where do the two feeds go? one is the main board what is the other. Could it be separate board for pv or car charger?

if the solar pv is wired directly into the main board add one clamp to the main boards feed tail after the meter.

Thank you so far - please see the wider shot attached below. The units on the left are for our air source heat pump (not currently in use/drawing power). The ones directly above the meter I believe are for the solar/inverter. As you say one feed is going into main board, the other seems to be going into solar and heat pump isolators.

 

[rwdl1984]

See a wider shot of system below showing cabling setup. Yes - I will buy a grommet, thanks for the heads-up.

 

[timhoward]

Are you saying it WAS where the red circle is?

To my understanding, to measure the output from the inverter it needs to be where the green circle is.

My other concern is that you appear to be missing some absolutely essential safety labelling warning of two sources of supply.

 

[rwdl1984]

Yes, originally the CT clamp for the solar/inverter was in the red position - this resulted in the inverter showing a very high load in the house (it was including the power produced by the solar panels in the house load, causing the batteries to discharge to compensate). However, the EV charger worked fine.

Should I move a CT clamp to the green-circled cable, and if so, which one, solar or EV clamp?

I'm not surprised by the lack of stickers - I'm not at all impressed by the company we hired.

 

[timhoward]

I should qualify that I have limited experience with solar, having only connected up a couple of Zappi systems.

In general terms I'd expect the EV CT clamp to be where it is, the purpose being to monitor the demand of the whole installation to comply with any grid limits that are set.
I'd expect the solar generation sensor CT clamp to be where the green circle is to monitor the invert output.

The arrow direction matters on the clamps, the EV CT clamp should point towards the consumer unit and the solar CT clamp should point towards the black connection block. So the two arrows should be pointing at each other if you follow along the cable.

At least, that is how Zappi works.

 

[Deleted account]

unfortunately my above idea will not work. Due to solar pv being on separate board, However there is a way, but it will require an electrician to do this it involves fitting another Hensley block to extend the line tail coming out of the meter.