Ground array: future project, what cables

[Post and beam]

I have enough space on our plot for a south facing ground array along the northern fence line of our garden.

Probably cannot afford to actually install this day one but if there is any money left ( yeah i know)once we move in i would like to put an array in place.

So the question is what cables and at what depth should i lay down, just in case. The consumer unit at the front of the house on the west side is 21 metres from the closest point that the array would be sited.

Thanks as always

keith

 

[Mattg4321]

Much better installing a duct with a rope through. 

[JohnMo]

  On 17/04/2024 at 21:00, Post and beam said:

I have enough space on our plot for a south facing ground array along the northern fence line of our garden.

Probably cannot afford to actually install this day one but if there is any money left ( yeah i know)once we move in i would like to put an array in place.

So the question is what cables and at what depth should i lay down, just in case. The consumer unit at the front of the house on the west side is 21 metres from the closest point that the array would be sited.

Thanks as always

keith

 

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Bit of a vague question without specifics about volts and amps. Or just duct with a pull rope then specifics can be sorted later.

 

You may be best to size the cable for DC instead of AC as DC tolerate voltage drop more easily.

 

Amoured cable can be surface run, so could follow a fence line for example.

[SteamyTea]

BS 7671:2018

 

https://electrical.theiet.org/wiring-matters/years/2019/77-september-2019/bs-76712018-frequently-asked-questions/

 

Half a meter deep at least.

[pudding]

https://www.tradepipes.co.uk/black-twinwall-duct-40mm-x-25m-coil?search_string=PM398 There you go, comes with a drawstring wire inside ready for future use.

[Bramco]

Ours is similar. We laid a 4 core armoured cable for DC in a trench, as @SteamyTea says at least half a metre deep. Use 4 core, so you can have your array in 2 halves, into separate MPPT connections on the inverter.

 

If you aren't going to install it immediately, get the sparky to install a spur to where you expect the inverter to installed and get that on the electrical certificate labelled 'solar PV'. This allowed us to do a self install and produce the electrical cert to national grid which they were happy enough with to give us the all clear on the installation.

 

Once National Grid were happy, Octopus were also happy to put us on one of their smart tariffs.

 

That way you avoid the dreaded MCS tax...

 

Simon

[Post and beam]

  On 17/04/2024 at 21:16, Mattg4321 said:

Much better installing a duct with a rope through. 

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Thanks and yes i thought that was the way to go. As stated above, is 500mm deep appropriate?

  On 18/04/2024 at 07:26, Bramco said:

get the sparky to install a spur to where you expect the inverter to installed and get that on the electrical certificate labelled 'solar PV'.

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Thanks for this as well, good idea.

 

As to JohnMo's point about being vague, yes totally accept that. That'll be my ignorance of this subject.  As it stands today i have no idea if the local rule makers will allow me to put an array in or of what size. It a conservation area.  I understand local micro inverters are the current idea.

 

The available fence line space would allow me a 30 metre run of panels on their ' long side' horizontal, if i do a single run. Neighbours on the other side of the fence would then not even see the array so no nuisance value to them.

[SteamyTea]

  On 18/04/2024 at 08:08, Post and beam said:

I understand local micro inverters are the current idea

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They for for extracting the best performance out of a shading compromised array.

Actually, they were for installers to make a few extra quid in most installations.

[sharpener]

  On 18/04/2024 at 06:26, pudding said:

https://www.tradepipes.co.uk/black-twinwall-duct-40mm-x-25m-coil?search_string=PM398 There you go, comes with a drawstring wire inside ready for future use.

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And when you draw the cables through also draw a second messenger so you have always got one in the duct for the next cable and so on...

[Post and beam]

  On 17/04/2024 at 21:25, JohnMo said:

Bit of a vague question without specifics about volts and amps.

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As i dont have the knowledge to answer this yet. Is there a table or a calculation i can use that would for example provide the necessary info for a 4, 6, 8 & 10kw array. or whatever is practical/allowed/sensible.

The house will be 200 square metres, UFH, Vaillant 7kw ashp, compulsory EV point out front.

[SteamyTea]

  On 18/04/2024 at 14:19, Post and beam said:

Is there a table or a calculation i can use that would for example provide the necessary info for a 4, 6, 8 & 10kw array

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Lots 

 

https://www.fabhabs.com/dc-cable-sizing-calculator

 

 

[Dillsue]

  On 18/04/2024 at 14:19, Post and beam said:

As i dont have the knowledge to answer this yet. Is there a table or a calculation i can use that would for example provide the necessary info for a 4, 6, 8 & 10kw array. or whatever is practical/allowed/sensible.

The house will be 200 square metres, UFH, Vaillant 7kw ashp, compulsory EV point out front.

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Can't your spark size the cable for you? He's gonna be signing off the install so getting him to spec the cable should minimise any problems.

[Post and beam]

  On 18/04/2024 at 19:06, Dillsue said:

Can't your spark size the cable for you? He's gonna be signing off the install so getting him to spec the cable should minimise any problems.

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If and when we get to that stage yes of course. But i like to learn.