Depth for buried DC cables

[Mr Punter]

11 minutes ago, Beelbeebub said:

you get no points for batteries.

 

If that is the case, make no provision for them.  Do not suggest to tenants that they are authorised to install batteries.  A world of liability for you.

[-rick-]

So these properties are all owned by a single person with no plan to sell separately? If you wish to preserve an easy option to sell separately it sounds a fair bit more complex than otherwise.

 

If operating as a pooled resource there may be options to get more efficiency out of the system. (Multi-tenant inverters exist, someone posted a link here recently).

[Beelbeebub]

2 hours ago, -rick- said:

So these properties are all owned by a single person with no plan to sell separately? If you wish to preserve an easy option to sell separately it sounds a fair bit more complex than otherwise.

 

If operating as a pooled resource there may be options to get more efficiency out of the system. (Multi-tenant inverters exist, someone posted a link here recently).

Yes, no plans to sell.

 

I've looked at the multi tenant systems (solshare or something). They are pretty pricey (5-10k) and have 15 outputs (5 x 3phases) so make the most sense in blocks of flats.

 

2 hours ago, Mr Punter said:

 

If that is the case, make no provision for them.  Do not suggest to tenants that they are authorised to install batteries.  A world of liability for you.

That is the most hard nosed approach but the benefit to the tenants is much more limited - especially with lower export rates.

[JohnMo]

22 minutes ago, Beelbeebub said:

especially with lower export rates

If MCS or octopus approved why not higher export rates, they are not limited to 3-4p kWh.

[JohnMo]

3 hours ago, Mr Punter said:

 

If that is the case, make no provision for them.  Do not suggest to tenants that they are authorised to install batteries.  A world of liability for you.

You don't need to, plug in batteries are almost here, if they want batteries they will have them like it or not.

[Beelbeebub]

22 minutes ago, JohnMo said:

If MCS or octopus approved why not higher export rates, they are not limited to 3-4p kWh.

I was thinking of the higher rates!

 

They were 15p, now 12p

 

And I suspect they will keep falling as solar generation gets more and more common.

 

https://www.theguardian.com/environment/2026/aug/02/solar-powers-record-share-britain-electricity-july

 

 

[Roger440]

On 02/08/2026 at 09:38, Beelbeebub said:

In favour hybrid systems so the battery generally needs to be next to the inverter.

 

I

It does? That is info that has passed my by.

 

Im unclear why the battery would know or care if the inverter is 5 or 100m away?

 

Whilst theres no batteries in my immediate future, longer term its likely.

[Beelbeebub]

51 minutes ago, Roger440 said:

It does? That is info that has passed my by.

 

Im unclear why the battery would know or care if the inverter is 5 or 100m away?

 

Whilst theres no batteries in my immediate future, longer term its likely.

Sorry I wasn't clear.

 

They don't normally need to be close though some of the sleek all in one type obviously do!

 

This was in the context of a long DC cable run from panels to inverter (and battery)

 

There was a suggestion about putting the inverter next to the panels and running the underground cable in AC.

 

If we used AC coupled batteries they could then be at the house connected via AC 

 

But a hybrid connects to the inverter over a DC line so if the batteries are to be at the house i'd need a DC line from the inverter by the panels to the house alongside the AC line from the inverter to the house!

 

Which defeats the object of putting the inverter by the panels (to avoid a buried DC cable) in the first place 😁

[Dillsue]

1 hour ago, Roger440 said:

It does? That is info that has passed my by.

 

Im unclear why the battery would know or care if the inverter is 5 or 100m away?

 

Whilst theres no batteries in my immediate future, longer term its likely.

The battery wouldn't care if the inverter is 5 or 100m away but your wallet would when you buy the connecting cable. Our battery comes with 50mm2 cables for a 1.5m run

[JohnMo]

10 hours ago, Dillsue said:

The battery wouldn't care if the inverter is 5 or 100m away but your wallet would when you buy the connecting cable. Our battery comes with 50mm2 cables for a 1.5m run

Yep, volts is key here, low volts mean big amps and big cables. So if your battery is 48v dig deep in the pocket, it won't be cheap. Have battery and inverter close.

[Roger440]

After much deliberation, going to run DC. Will add a year to payback time though

 

Cracking on

 

 

[-rick-]

46 minutes ago, Roger440 said:

After much deliberation, going to run DC. Will add a year to payback time though

 

Cracking on

 

The proper way to dig a trench! Glad to see you moving forward. Have you got someone lined up to get the electrics hooked up and signed off?

Edited 6 hours ago by -rick-

[JohnMo]

58 minutes ago, Roger440 said:

After much deliberation, going to run DC. Will add a year to payback time though

 

Cracking on

 

 

Should be laying GSHP pipes while your at it!

[Roger440]

2 minutes ago, JohnMo said:

Should be laying GSHP pipes while your at it!

No need, they are going in the lake.

[Roger440]

15 minutes ago, -rick- said:

 

The proper way to dig a trench! Glad to see you moving forward. Have you got someone lined up to get the electrics hooked up and signed off?

An expensive way to dig a trench though!

 

I do have someone if i need them.  Ill be doing all the work though. Slowly.

 

Mounting the panels in a cost effective manner, than can resist serious wind, and be close to a vertical angle is my current challenge, especially after the increased costs of 100m of DC cable.

[-rick-]

9 minutes ago, Roger440 said:

An expensive way to dig a trench though!

 

Depends on the cost of labour. Compared to 'free' labour sure. But it's a big job to dig by hand solo, especially if not a spring chicken.

 

9 minutes ago, Roger440 said:

I do have someone if i need them.  Ill be doing all the work though. Slowly.

 

Good, worth making sure you have talked through what you are doing with them. Better to find out now that they need something specific rather than after you've filled the trench in.

[JohnMo]

20 minutes ago, Roger440 said:

No need, they are going in the lake.

Even better

[Roger440]

2 hours ago, -rick- said:

 

Depends on the cost of labour. Compared to 'free' labour sure. But it's a big job to dig by hand solo, especially if not a spring chicken.

 

 

Good, worth making sure you have talked through what you are doing with them. Better to find out now that they need something specific rather than after you've filled the trench in.

 

Well i have a digger. But not a narrow trenching bucket. Could buy one, but thats half the hire cost, plus wont be neat like this.

 

Discussion have been had, hence going back to a DC cable. That way i have no real limitations plus allowing for future expansion.

 

Payback is still hopless though. Im still questioning my sanity. It only really makes sense if electricity prices continue to rise much quicker than inflation. My judgement is that they will. If they dont, frankly its pointless.

[-rick-]

22 minutes ago, Roger440 said:

Payback is still hopless though. Im still questioning my sanity. It only really makes sense if electricity prices continue to rise much quicker than inflation. My judgement is that they will. If they dont, frankly its pointless.

 

Mind giving a breakdown of what you think the costs/return are? I thought you had the panels and inverter system for free. That should make the payback quite easy, even if you have elevated installation costs.

[Roger440]

32 minutes ago, -rick- said:

 

Mind giving a breakdown of what you think the costs/return are? I thought you had the panels and inverter system for free. That should make the payback quite easy, even if you have elevated installation costs.

Well, ive been doing most of it using AI, but im lookinng at in excess of 10 years i think. Assuming i buy a battery.

 

Yes, i do have the panels and inverter free, though the inverter wont be much use with batteries.

 

Im looking at over £2k just in cabling, hire etc. The solar array needs to be bolted to something. Thats looking quite expensive too, but undecided on what yet. The field is pretty exposed to the east, north east. (we have planted a hedge along that side) And we are 900ft up. So needs to be pretty well put together, whatever it is.

 

9000kwh is our current consumption, heavily biased towards winter due to the workshop.

 

So ive got, lets call it £4k on the solar install, and another £2-3k for a battery (5kw) and associated gubbins and connection.

 

So im £6-7k in the hole. Obviously lots of variables around tarrifs and other such stuff, but no EV, so no supercheap overnight rates. Exported limted to 3.86.

 

 Playing numbers, at best i might save £400 a year on my electricity bill.

 

If i fit a couple of AC units in future (likely) clearly that will skew things for the better. Havent factored in heat pump. Guess if i do that ill need to increase the size of the system. Otherwise it will be cheaper to run on oil as now. (current price blip excepted).

 

Minor bonus will be only having to run the genny during the day when the electricity supply falls over. Again.

[FarmerN]

5 hours ago, Roger440 said:

After much deliberation, going to run DC. Will add a year to payback time though

 

Cracking on

 

 

Just check spoil from trench for bits of land drain, clay or plastic. Up to you if you repair any old drains you cut, but at least you know they are there if a wet spot develops in future.

We have GSHP , one of the down sides is a dry field is now wet !