How to wire now, for future solar PV

[Zebra579]

I am renovating a cottage which has a large flat roofed extension on the south side. I don't have the funds right now to install solar PV, but while I am rewiring the house and have the floorboards up, would it be a good idea to run any cabling which would allow me to install solar PV in the future?

What type of cable should it be, and how are cable sizes calculated for PV? Are there any other particular requirements or things I should think about?

(I'm a Part P registered spark, but not MCS qualified.) Thanks!

 

[Iggifer]

http://www.tlc-direct.co.uk/Main_Index/Cable_Index/Solar_Cable_PV1/index.html

Most installations are fine with 4mm but if you're unsure of your array specs, it might be worth just bumping it to the 6mm

This cable to where your inverter is going to be, then T+E to your CU

Depends where you want your inverter I suppose, some people will have them by their CU, some will have them in their loft. I would personally have mine by my CU, that way if the inverter trips for whatever reason, you don't have to go all the way up to the loft to reset it.

Either way from the inverter location to CU is T+E, the MCB for solar arrays will be a 16a MCB, so choose your size of T+E appropriately taking into account any derating factors, I think 2.5mm should cover your for all eventualities

 

[ajstoneservices]

We run the ac side in either 4mm-6mm t&e.

 

[Zebra579]

Ok great. That's the answers I was looking for! The panel end of the cable could presumably just be left coiled up on the flat roof for now, and if the inverter can go in the cupboard under the stairs with the CU, then I don't need to do any of that wiring now.
The inverters look quite big though, aren't they?

 

[Iggifer]

they can get fairly big, but their shape means they will usually fit somewhere in an under-stairs cupboard, just have a look at some spec sheets and see if one you like the look of will fit, maybe adjust the position of the CU to suit.

I would leave the cable coiled up inside for now, no point in unnecessarily exposing it to the elements (but this is one reason not to use T+E for the DC run - you cant use it outside)

 

[westie101]

Er

We run the ac side in either 4mm-6mm t&e.

The ac side is after the inverter, so what you suggest is a non-starter.

 

[ajstoneservices]

If you're putting the inverter under the stairs or anywhere remote from the roof space then there is no point running a cable as it won't be suitable.

The array to inverter will be dc cable not t&e.

 

[Iggifer]

If you're putting the inverter under the stairs or anywhere remote from the roof space then there is no point running a cable as it won't be suitable.

The array to inverter will be dc cable not t&e.

Why won't it be suitable?

And oops by bad re: the T+E comment, totally read it as DC not AC

 

[ajstoneservices]

Er

We run the ac side in either 4mm-6mm t&e.

The ac side is after the inverter, so what you suggest is a non-starter.

er, clearly i wasn't talking about the dc side was I

 

[Iggifer]

i think Westie was talking to me confusing my AC/DC





sorry, couldn't resist

 

[viewer]

Questions (only-and not electrical); How much heat will you need to get rid of from an inverter (given the <16A MCB limit)? Is putting it under the stairs OK and would it need extra fire protection as a fire under a staircase would be a serious matter?

 

[ajstoneservices]

I have only ever fitted one inverter in an under stair cupboard. It was an sma hf and it's never been a problem. There are loads of questions/answers about inverter locations on the link I gave.

http://www.electriciansforums.co.uk/photovoltaic-solar-panels-green-energy-forum/

I gave the link in another thread.