Leakage current on installations with solar

That's far too much leakage. Why arent the RCDs tripping?

Something wrong there, has your meter been checked against another meter?

I've checked my own house and another, and it seems within expected range, about 3.5mA
Yes very high leakage and I can't understand where it is coming from, hence why I wonder about he 
solar. 
DId some basic tests I haven't disconnected anything,  took a Zdb and that was fine 0.12Ω
Contact voltage tests fine
IR Line-CPC fine
 

Oh and RCD test fine Ramp 24mA and time around 28ms

T-N-C-S presumably. Fault downstream on a neighbours property causing neutral current diversion through your property? That's a total guess.

Totally isolate the PV, even the CPCs, to see if it is that causing the fault. Presumably there is an isolator on the DC side to turn that off?

Narrow down where it is coming from, as you say, anything with a CPC or a class one accessory could be the cause with a N-E fault.

The leakage current is very high on the tails of the main board,

The main board then, not the solar/battery one? I take it you're clamping the L&N tails but leaving the earth out of it, Sounds more like a conventional fault. If it increased with load I'd suspect a N-PE fault somewhere (although it could still be that, if loads in neighbouring properties happened to be pulling the supply N up or down). The symptoms you mention sound more like rodent damage to cables to me though or damp ingress. Was you IR test done with the c.p.c.s still connected to Earth? Other possibilities might be a shared N between the sub-db and the main one - hopefully unlikely for a recent install, but maybe if there are controls/sensors involved.

  - Andy.

So we keep a record of leakage on every inspection we do. This one is fairly typical of what we are seeing in a small single phase installation. All circuits on, but not necessarily with load. Top photo complete installation, bottom photo measuring separate tails to the PV board which then supplies the inverter. 

Yes the IR test between L and E were with everything connected, (board isolated)
I have not yet disconnected any neutrals to test between N & E
This amount of leakage is new to me and I wanted to be cautious about any harmful current appearing on disconnected conductors.

There is a issue with the RCD tripping intermittently, I was just trying to see if I could narrow down the circuit with earth leakage tests by
switching on the MCBs one by one, but everything is masked by such high leakage, every circuit increases the amount of mA considerably.

With everything isolated including solar I do get 0V

I think what I need to do is isolate the main board including earthing conductor, and split the neutrals and do some proper IR tests
so basically ignoring the solar side for now. I'm comfortable with that. I have zero experience of solar, so that would need someone else.
There seems to be a gap in training for working around solar installs, and possible impacts on the installation.
Also safe isolation around solar.  Plenty of courses showing you how to throw it in. 

Thank you.
I find leakage current  interesting but don't really grasp whats going on.
How it can affect the RCD and how it dosen't.
Leakage from other systems, and potential DNC.
knowing if its expected or not right.

I think what I need to do is isolate the main board including earthing conductor, and split the neutrals and do some proper IR tests

Generally you leave the c.p.c.s connected to the means of earthing - otherwise you're more likely to miss damaged cables that are in contact with the general environment (e.g. damp masonry or structural steel) but not the c.p.c..

   - Andy.

Yes I don't disconnect the cpcs