What size cable for Solar PV system.

[revelation]

Hi all

 

This is not work we plan to carry out ourselves.  However, our landscaping is happening and our sparky 'delayed'.

 

We are planning to put a 4kw-6kw solar PV system on a single-storey outbuilding.  The inverter, batteries etc... will all be inside this outbuilding.  

 

As our paths and garden are half dug up we wanted to run whatever cables we need in the ground and leave access on both ends for whenever the sparky turns up.   The distance between the outbuilding and the consumer unit is approximately 30m.

 

We also need power for the outbuilding too.  Therefore can anyone recommend what cables (armoured I assume) need to be put into the ground?

 

Thanks in advance. 

[ProDave]

I would put 10mm 3 core steel wire armoured.  That will feed a sub main, to the outbuilding and your solar PV would feed into that.

 

But we don't know what is going into the outbuilding so that is a bit of a guess.

 

As you talk of batteries there will probably be some data cable or a cable for a current clamp that has to go on the main incoming cable by the meter.  I would be thinking of Cat 6 network cable for that?  anyone else care to advise?  Is that available in a SWA form or would it have to be outside Cat 6 in conduit?

[Radian]

When we got PV on our outbuilding and I asked about batteries in the same building the installer insisted that we could only do it with an AC battery that had to be within a few meters of the utility meter in the house. This was because of not having any way of connecting a current clamp from the outbuilding to the incoming mains. A cat 6 cable might suffice. Or perhaps make it a 4-core SWA to hedge your bets.

[ProDave]

I run the current clamp cables for my home made PV diverter through about 25 metres of 6 pair SWA telephone cable that gets them into the under stairs cupboard, then about 10 metres of cat 5 inside the house to get them to the plant room.  It seems to work okay.  But no guarantee it will work with any particular system.

[Dillsue]

Run a beefy SWA as suggested and a run of blue alkethene water pipe with a draw wire in it and you can pull in whatever data cable you/your installer wants.

[S2D2]

6 hours ago, ProDave said:

I would be thinking of Cat 6 network cable for that?  anyone else care to advise?

 

6 hours ago, Radian said:

only do it with an AC battery that had to be within a few meters of the utility meter in the house

 

As a point of reference, the standard install practice for my Solax hybrid inverter's CT clamp is to extend it (ours was done with CAT6 internally, the manual does not specify) and the install manual says not to go over 100m, so plenty of room to play with. Ours runs ~10m with no issues.

[Ronski]

I've got an ET112 meter in the under stairs cupboard, then about 20 meters of external Cat5 which runs through 20mm water pipe to our detached garage to an RS485 to USB adapter, and that works perfectly. No need for a draw string just fed two cat5e cables down the pipe together.