Solar panels circuit MCB size

[driverman]

Hi, can't get hold off solar people at mo, to ask what is required in terms of MCB required for their solar panels. when I met them ages go, they said just leave a spare way and I'm pretty sure they said they would put in a 4mm cable. Anyway i'm going to install a board complete with RCBO's.
As it's 4mm cable. I'm thinking 32A but I have no idea of the actual workings / requirements of Solar Panel heating. I need to place the order ASAP. Would 4kw system sound right? Thanks

 

[davesparks]

Why not just leave a spare way as requested?

 

[driverman]

Why not just leave a spare way as requested?

I'm ordering the SBS RCBO's to order. It's a love job (family). Thought it would be easier for me to get it. If it was just a standard MCB I would agree with you.

 

[davesparks]

Then you'll have to ask the solar people what size they need!
What is the power rating of the PV system? Their cable will most likely have been sized based on the strict volt drop requirements they have rather than the current so I wouldn't go making assumptions based on that.

 

[Leesparkykent]

what kw is the pv system? most domestic pv systems are a max of 4kw and normally goes on a 16amp. they have probaly used 4mm cable to account for the maximum allowed volt drop on a pv system of 1%

 

[Leesparkykent]

ive just seen solar panel heating in the OP?

 

[driverman]

what kw is the pv system? most domestic pv systems are a max of 4kw and normally goes on a 16amp. they have probaly used 4mm cable to account for the maximum allowed volt drop on a pv system of 1%

Yes as stated above. Customer mentioned 4KW. Been trying just before Christmas to contact Solar People, (possibly on hols)

 

[driverman]

ive just seen solar panel heating in the OP?

OPPS, not heating, that the AHSP! lol

 

[gnselectricals]

Would check with installers as we don't fit 30ma protection due to excessive earth leakage from certain inverter types

 

[driverman]

Would check with installers as we don't fit 30ma protection due to excessive earth leakage from certain inverter types

Thanks very much for that. I didn't even consider that aspect. Hopefully find out when I get hold of the solar people.

 

[uksparks]

We are about to get PV installed in a couple of weeks, at my last house, they put a mini cu next to the old board, presumably if I change the consumer unit in my new house as I intend to do, I can leave spare ways and they can use that to feed the inverter etc?

 

[davesparks]

Probably worth asking the people who will be installing it.

 

[driverman]

Probably worth asking the people who will be installing it.

Yes, I agree. I have stopped the order going ahead for the Con-unit until I have resolved the issue with the solar Panels.

 

[Leesparkykent]

What's the installation method of the 4mm cable that's been run in? If it's buried at a depth of <50mm the the circuit is going to have to be RCD protected regardless of what inverter is going to be installed! The only time you normally have a problem with a pv inverter on an RCD is when the inverter is transformerless and I don't personal use these due to this reason.

and uksparks if you do change your consumer unit and leave a spare way for the PV circuit make sure it's a high integrity board or main switch and rcbo,s as you shouldn't put the inverter on the RCD with the other circuits as the inverter can take up to 500ms to disconnect.

 

[driverman]

What's the installation method of the 4mm cable that's been run in? If it's buried at a depth of <50mm the the circuit is going to have to be RCD protected regardless of what inverter is going to be installed! The only time you normally have a problem with a pv inverter on an RCD is when the inverter is transformerless and I don't personal use these due to this reason.

and uksparks if you do change your consumer unit and leave a spare way for the PV circuit make sure it's a high integrity board or main switch and rcbo,s as you shouldn't put the inverter on the RCD with the other circuits as the inverter can take up to 500ms to disconnect.

thanks, just noticed this. the inverter will be sited nearby the con -unit, so might be installed in trunking now.

 

[Leesparkykent]

How you going to get the dc cables from the roof to the inverter?

 

[shanky887614]

How you going to get the dc cables from the roof to the inverter?

the dc cables will probably in conduit or similar on the outside of the building, only +/- so not many cables

 

[driverman]

the dc cables will probably in conduit or similar on the outside of the building, only +/- so not many cables

Surly, you wouldn't do that on a complete new build would you?

 

[shanky887614]

Surly, you wouldn't do that on a complete new build would you?

i wouldn't but to get the cables down from the loft a lot would because of how much time it would save.

 

[driverman]

i wouldn't but to get the cables down from the loft a lot would because of how much time it would save.

Yes, if working on an occupied house, possibly agree. but it would have to installed in either black conduit or black trunking. I don't like to see any surface wiring on domestic properties either internally or externally looks awful, no matter how neat it has been installed, just awful.