Off-grid experience

[Originaltwist]

How about a wood burning stove and a heat bank? A 14kW Clearview 750 with a 7kW back boiler works well for your size of house. You get almost permanent hot water and heating too. Twin tanks are best. A gas boiler is a good addition and will get little use to trouble your wallet. I had this arrangement and used to run the boiler for 10 minutes every morning just to make sure the showers were in the bank. Gas use was so low that caravan type bottles were sufficient.

Then bigger PV and battery along with a Victron Quattro to pull in a generator occasionally. Then Robert's your father's brother.

[jack]

2 hours ago, Muellar said:

 

lol... you've reminded me of a Father Ted sketch @Conor, thank you! And yes, it's how I felt when I saw the calcs come through I just couldn't believe the figures being presented but they stood by their calcs and this is an area I get confused in so I left them to their stuff being told by the architect they were good and could 'work wonders with NIE'.... unfortunately not the wonder I'd hoped for.

 

If they did calculations, then they ought to be able to present them and explain their maths. You've paid for it, so demand they show their working.

 

40 kW is 166 A.

 

Like you're planning, I have a "big house all electric" (290 m², 5 kW ASHP, 7.2 kW car charger, 3 ovens + induction hob) and my very conservative electrician was more than happy with our existing 100 A supply.

[saveasteading]

1 hour ago, Muellar said:

from his experience would need 35-40kVA

You need someone with more experience then.

 

Do you have a schedule of the power needs? Ask for it.

You don't just add it all up. I think the term is divergence, for not all toasters, hairdyers etc being on at the same time.

[SteamyTea]

4 hours ago, Muellar said:

tried this and got myself in a pickle

When I am free from n a couple of days (only got one day off this week), I shall try and knock up a generic spreadsheet.

 

Is NIE Northern Ireland?

Think they have different rules there.

[jack]

29 minutes ago, saveasteading said:

I think the term is divergence, for not all toasters, hairdyers etc being on at the same time.

 

Diversity.

[saveasteading]

 

I understand that multiple electric car chargers can also sort themselves out in some way.

[jack]

Yes, I think some of them can. In my case, even 2 x 7 kW car chargers and the ASHP pump running flat chat on top of ordinary background loads wouldn't take me anywhere near the limit.

[Muellar]

1 hour ago, SteamyTea said:

When I am free from n a couple of days (only got one day off this week), I shall try and knock up a generic spreadsheet.

 

Is NIE Northern Ireland?

Think they have different rules there.

 

Yes, Northern Ireland Electricity. I've made my own attempt at a sheet but I got an even larger figure... duh. Thanks for offering to knock one up for me, i'm very grateful.

 

 

Edited 17 hours ago by Muellar

[Muellar]

3 hours ago, Originaltwist said:

How about a wood burning stove and a heat bank? A 14kW Clearview 750 with a 7kW back boiler works well for your size of house. You get almost permanent hot water and heating too. Twin tanks are best. A gas boiler is a good addition and will get little use to trouble your wallet. I had this arrangement and used to run the boiler for 10 minutes every morning just to make sure the showers were in the bank. Gas use was so low that caravan type bottles were sufficient.

Then bigger PV and battery along with a Victron Quattro to pull in a generator occasionally. Then Robert's your father's brother.

Now I'd originally thought of having something like that, but was told 'don't be silly'. i'd seen a Woodfire EX15 that i'd quite liked, and had seen that not only would it be a nice feature, but we'd also have back up should things go bad - like recently during the storms and power went down.

 

This whole experience with the cost of power has really made me think that maybe i'd dump the whole induction hob thing and go with Calor gas tank for cooking use and also a boiler to be used now and then, with adding in the Woodfire EX15 for use during winter and as a back-up.

 

Then go back to NIE and ask 'how little can you give me' just for small power and other items.

[ProDave]

Do NIE ask for calculations?  If not just pick a low figure like 12KVA and re apply.  They are not going to connect you with a thinner cable just because you ask for a low rated supply.

 

If they question the change, tell them your original estimate was made by someone not understanding how it is done, and now you have a more accurate understanding of the energy needed for your house.

[Originaltwist]

The Woodfire EX15 looks nice although I have no experience with them.

I go for the Clearview because:

Stainless steel back boiler - quick to replace if it fails - which they don't

I never go more than 50% heat to water - condensation on the back boiler and not enough to the room otherwise.

Clearview stoves don't break.

Chuck a big log in and they will stay in all night - saves a fortune in matches.

 

I guess it's just down to what you fancy in the end.

[Roger440]

For what its worth, before we bught this place, we looked at a place a few miles away that was off grid. Was running on a ramshackle collection of old gennys, some lead acid cells etc.

 

That would be no use to me. I rang these guys. https://www.energy-solutions.co.uk/applications/off-grid/residential

 

At the time, £40k, all in, solar, batteries, generator, control system etc. Completely automatic. So long as its filled with diesel. The cost of a connection would far exceed that, and if you take out the capex on it, your actual cost per unit of electricity was way way lower than the grid.

 

I thought it was quite a sensible solution. Didnt buy the house though.

 

The one we did buy has an 11kv pole directly behind my barn. I wanted 3 phase in the barn. Still came in at £17.5k plus VAt with me doing the trenching. Im sure that the minute they think you might spend money, they start adding in loads of extra stuff, that would normally be "maintenance and replacement" and get you to pay for it instead.

 

I dont have 3 phase. 

 

It does mean, however, with both a house and barn needing heating, oil remains my only sensible option as otherwise overall load starts to get to high if ASHP's were to run both along with everything else. But, tough, not paying £20k. To have higher priced electricity than a domestic supply.

 

Its a good thing that back in the 50's when they were connecting houses to the grid for the first time, they operated in a rather different way!

 

 

[Alan Ambrose]

OK, supposing in December you use 90% of your proposed 40,000W / 175A supply. There are 744 hours in December, so that’ll be 744 x 40 x 90%  = 26,784 kWh. At, say, 20p per kWh, that’ll be £5.4K for December. Maybe £30K of electricity a year given that you’ll be using far less in the summer? Is that what you’re expecting?

 

No? Why not? So, perhaps you won’t be using that much electricity and maybe you don’t need that big a supply. Search for ‘Veyron’ on the forum and you’ll see related discussion around this subject.

 

 

Edited 7 minutes ago by Alan Ambrose