Solar system tripping out mains.

[moggy1968]

I had some concerns when you first posed on this forum because the inverter is quite a poor match to this system being very overspecced. My preference would be a 3.6kW and the most I would go to is a 4kW inverter.

Most larger systems (i.e one around 4kW) require a 100ma RCD. you can often get away with a 30ma but they can sometimes cause tripping. Some manufacturers even specify 300ma RCDs.

As above, if it doesn't need an RCD don't use one. If your installer says every circuit needs and RCD, as I have been told by more than one electrician, then they don't know what they are talking about.

Generally I try and keep PV completely seperated from the household circuits by using a sub board fed from a supply off the mains but if they move it to the unprotected side of the board you should be ok (assuming it doesn't need an RCD for other reasons)

I also have concerns about the cable they have used, it looks like DC cable to me. Totally wrong and their appears to be no earth, which there should be (not array earthing, which is a different matter. There should be an earth running from the inverter back to the board. If they used 3 core cable or twin and earth it would be one of those, but they haven't)

The cabling is quite untidy and should be clipped up, cable should not be allowed to hang on it's terminations.

It does make me rather concerned about what else they may/may not have done.

still, they wired the meter the right way round, thats a common mistake!

 

[moggy1968]

Fundamentally RCDs are required for.
1. Circuits with high disconenection times, i.e. on a TT circuit where the main earth is an outdoor spike.
2. Socket circuits.
3. All circuits in a bathroom, shower room
4. all circuits supplying power to mobile equipment
5. cables burried less than 50mm in a wall not protected by earthed metal conduit

surface mounted cabling or cabling burried at greater than 50mm does not require RCD protection unless required for one of the other reasons above (eg feeding a socket, with a few exceptions)

 

[Glen Powell]

Another possible issue is the type of RCD used I am sure that a type "B" RCD should be used on all PV installs (that is my interpretation of the regs) therefore the RCD on the DB / CU needs to be replaced or, my prefered method, a 2 way added with henley blocks fitted with a type "B" RCD.

Using the DC wire is a way of ensuring a good connection between the generation meter and DB instead of using insulated tales. The correct way is 10mm insulated tails but a lot do not use it as it is a pain to use. This is why I prefer garage boards as it is easier to get the tails into the non cluttered DB.

 

[SolarCity]

The type 'B' RCD debate rumbles on. The guidelines aren't exactly clear.

The way I see it is that a type 'B' RCD is only needed on a system with TL inverters IF the inverter has no other means of preventing DC to AC fault current occurring. If an RCD is needed for any other reason then I believe that a standard RCD is suitable.

Others see it differently.

 

[BruceB]

If I have identified his inverter correctly then it has a transformer, is galvanically isolated, and so should not need a type B rcd.

 

[lennyg]

I have not been able to get to the bottom in identifying the inverter other than from the masterlog software. XS6500 [14]. Would the use of an overspecced inverter account for what I think is relatively low output - a max at the moment on a perfectly clear day with the sun at 90 degrees to the array of 1.8kw ? Futher to this, the cable from the meter into the CU has writing on it "TOPSOLAR PV ZZ-F(A5) PV1-F 0.6/1 kw". I can't read the rest at the moment - does this identify it as suitable for purpose?

Thanks again

 

[moggy1968]

Agree with the above, type B RCD not needed.
Looks like Dc cable to me but I can't identify it positively from the details given

 

[lennyg]

This is the cable that goes from the export meter to the CU http://www.topcable.com/content/baja_cables/Topcable_eng_33_topsolar_ZZF.pdf

 

[BruceB]

They are using dc cable for the ac side. There is not necessarily a problem with that - in many ways the dc cable is much better quality than some ac cable. The important thing is that an earth must go to the inverter. Strictly there should be an earth going to the isolating switch also, but there is no real safety issue if the earth misses that out.

 

[PC Electrics]

Ask your installer if it is possible to move the circuit to the non-RCD protected side of the board. It may be the case that the way he has wired the installation means that it requires RCD protection - if not, then this is a very simple solution.

It could be put on the non rcd side via an RCBO. I recently asked Hager Tech if their RCBOs work "in reverse" for this very reason. They replied 'yes'.

Mind you, M2 board, oh dear!

 

[PC Electrics]

And I'm pretty sure a Hager RCBO will fit into an M2 board ok.

 

[yellowvanman]

Should mix MCBs of a different make into a consumer unit!

 

[dansk]

weres the CPC? then i wonder whats down for the R1+R2 test? its difficult to see.

 

[lennyg]

I'm out of my depth a little here.... would any photos help?

 

[MorganPVI]

A photo of the wires from the CU heading to the loft would be useful/

 

[Gavin A]

weres the CPC? then i wonder whats down for the R1+R2 test? its difficult to see.

I think I spy a green and yellow cable running up the side of the consumer unit next to the SWA(?) cable, which I'm thinking might be coming from the AC isolator, which would slightly improve the situation compared to my first thoughts, but using the dbl insulated single core PV cable in that way seems dodgy as to me due to the lack of cpc as you say.

 

[dansk]

well theres always more than one way to skin a cat as they say, but it just doesnt look good and most electricians wouldnt do it like that i guess.

 

[lennyg]

I think I spy a green and yellow cable running up the side of the consumer unit next to the SWA(?) cable, which I'm thinking might be coming from the AC isolator, which would slightly improve the situation compared to my first thoughts, but using the dbl insulated single core PV cable in that way seems dodgy as to me due to the lack of cpc as you say.

The green cable runs from the isolator to the CU, so I assume that the cable from the inverter in the loft to the isolation switch is twin & earth.

 

[lennyg]

A photo of the wires from the CU heading to the loft would be useful/

Can you please clarify? The cables from the CU run to the meter, then the isolator, then to the loft. What would help you see?

 

[Earthstore]

What area do you live, if someone on here is local they might pop around and advise you.

I hope this helps.