Off-grid experience

[Muellar]

Hi

 

I've had a crazy quote for power supply and wondered if anyone has had experience of going totally off-grid at least for electricity supply and if there's someone you've known of who's been able to solution up a whole system?

 

I'd already got plans to put in a 5.2kW pv array with battery packs etc and I'm thinking i'd be happy to go with the extra cost of a wind turbine (which will need planning) and then a back-up generator, but i'm lost as to how to work out the calculations with any degree of accuracy.

 

Merry Christmas and best wishes for 2025.

David

[MikeSharp01]

Can we ask how crazy the supply cost was because you are already stacking up cost on the other side. EG generator & wind turbine etc?

[SteamyTea]

4 minutes ago, Muellar said:

then a back-up generator,

Why not a generator and some battery storage?

You could, with a bit of simple plumbing claim some thermal energy from the generator.

 

The main thing with off grid living is to reduce usage to a ridiculously low level. This will probably mean a total redesign if your home. May be too late to do that if you have planning already.

 

Small, domestic, wind turbines are pointless. The physics is against you.

 

It is very easy to think you can live with a log fire and a couple of lights, but realistically you want a washing machine (about 2 kWh per wash), a fridge and freezer (0.5 kWh/day), extractors, maybe off grid sewage and lights (another 2 kWh/day) and you have already used up your winter PV production.

 

Find a decent mechanic and make a small CHP unit on a petrol engine (gasoline us 15p/kWh).

[saveasteading]

4 minutes ago, SteamyTea said:

Small, domestic, wind turbines are pointless. The physics is against you.

I just want to emphasise that. The people that sell them tell outrageous lies about them. 

Think of them on yachts. There is always a brisk breeze and they can only trickle charge a battery and run a few lights. Inland the wind is many factors less. Nobody fits them on high office block roofs any longer, even to tick a sustainability box. 

I'm remembering construction exhibitions 20 years ago where there would be ten stands with the things, and Architects started specifying them. I refused to price them into jobs and it was an awkward argument.  All these companies have gone.

 

Solar and very big batteries ok, esp if you design the building for minimal demand.

But if it's £20k for mains, take it.

[SteamyTea]

3 minutes ago, saveasteading said:

17 minutes ago, SteamyTea said:

Small, domestic, wind turbines are pointless. The physics is against you.

I just want to emphasise that

I used to work for a small turbine manufacturer, we made a 5 kW turbine.

It cost about £20k to install, and that was 20 years ago.

Even on a good site, it would struggle to produce 10 MWh/year. Most likely half that, so no better than PV, except it works at night and in winter.

 

I would, if going off grid, go with CHP, PV and a modest amount of storage.

[BadgerBodger]

We lived with no mains for about 15 years (90s to late 00s, I was just a kid) We had an old Lister diesel generator. It was a different life, we were much more oriented around being outside and one was very much at one with the seasons. We lived in a very small house and had the power on for an our or so in the morning, and then a couple in the evening. Through winter it was on longer (from dusk while 2200). Our heating was mainly from an open fire but we also had a gas boiler from an LPG tank. There was no TV. We did have a water connection and a telephone line though! 
 

AMA

[Dillsue]

Have a good think about who's looking after all the off grid gubbins if somethings gone wrong and you're not around or are taken ill. Not sure the type of property your looking to power but if you come to sell you'll likely be selling in avery niche market.

 

The Victron forum is where I'd start looking for ideas but no idea if the knowledge base extends to whole house design??

[Muellar]

On 22/12/2024 at 16:48, MikeSharp01 said:

Can we ask how crazy the supply cost was because you are already stacking up cost on the other side. EG generator & wind turbine etc?

£35k to have the connection to the grid via NIE who want to upgrade the local transformer.

[Muellar]

On 22/12/2024 at 17:18, SteamyTea said:

I used to work for a small turbine manufacturer, we made a 5 kW turbine.

It cost about £20k to install, and that was 20 years ago.

Even on a good site, it would struggle to produce 10 MWh/year. Most likely half that, so no better than PV, except it works at night and in winter.

 

I would, if going off grid, go with CHP, PV and a modest amount of storage.

 

Thanks @SteamyTea... i've already got a quote for 5.22kw PV array with 2x batteries/inverters etc, but that won't deliver that amount all the time so I'd thought of adding in a wind turbine as we are on a hillside. I see there's micro CHP which could be a route as that would supply the heating/hot water so woudl offset what the ASHP would have consumed. Ideally I need to find someone who can do a proper calculation on the power needed so I have that with more certainty that the bowl of porridge it currently is for me!

[Muellar]

On 22/12/2024 at 16:55, SteamyTea said:

Why not a generator and some battery storage?

You could, with a bit of simple plumbing claim some thermal energy from the generator.

 

The main thing with off grid living is to reduce usage to a ridiculously low level. This will probably mean a total redesign if your home. May be too late to do that if you have planning already.

 

Small, domestic, wind turbines are pointless. The physics is against you.

 

It is very easy to think you can live with a log fire and a couple of lights, but realistically you want a washing machine (about 2 kWh per wash), a fridge and freezer (0.5 kWh/day), extractors, maybe off grid sewage and lights (another 2 kWh/day) and you have already used up your winter PV production.

 

Find a decent mechanic and make a small CHP unit on a petrol engine (gasoline us 15p/kWh).

 

We've got 300m2 so I guess size is maybe the issue as we've got a very low overall need for heating as a result of the ICF/Flooring/Roof and glazing (most glazing on South/West). All indications were we only needed a 6-7kw ASHP. The micro CHP may be the way to go given the cost NIE are wanting to upgrade the transformer and lay in the new supply @£35k. it may be that I just have to 'suck it up' but I feel they want a silly amount for what is a well designed home.

[Iceverge]

Is your house completely in the middle of nowhere? 

 

Can you settle for a smaller supplier and buffer it with an on-site battery for peak loads? 

 

Would it be possible to organise the routing from a suitable transformer to your house yourself and just bury a chunky cable on your land? 

 

Can you move the house?

 

 

 

 

[Gus Potter]

On 22/12/2024 at 16:55, SteamyTea said:

Why not a generator and some battery storage?

You could, with a bit of simple plumbing claim some thermal energy from the generator.

 

The main thing with off grid living is to reduce usage to a ridiculously low level. This will probably mean a total redesign if your home. May be too late to do that if you have planning already.

 

Small, domestic, wind turbines are pointless. The physics is against you.

 

It is very easy to think you can live with a log fire and a couple of lights, but realistically you want a washing machine (about 2 kWh per wash), a fridge and freezer (0.5 kWh/day), extractors, maybe off grid sewage and lights (another 2 kWh/day) and you have already used up your winter PV production.

 

Find a decent mechanic and make a small CHP unit on a petrol engine (gasoline us 15p/kWh).

I love @SteamyTea post above. In a few lines he spells out what you need to do and why.

 

Don't forget the saving that you will make on the standing charge for gas and electricity.. it maybe only a pound a day but that could pay for maintenance of a generator. changing the filter and so on. That's my tuppance!

 

Combined heat and power (CHP)..it's a no brainer in my mind.. there is a massive amount of heat to be extracted from the exhaust gases of a generator. Mind you it needs to be done safely..I would make sure I put all that gubbens in an out house.

 

56 minutes ago, Muellar said:

We've got 300m2 so I guess size is maybe the issue

I think this may be an advantage prid pro quo.. provided you design your house more as a box, like a long house.

[SteamyTea]

7 hours ago, Muellar said:

Ideally I need to find someone who can do a proper calculation on the power needed

You can do that yourself.  Try working out what you already use in your current home.

You can get into the nitty gritty by getting an energy monitor that logs data every Wh, or look at your smart meter data that averages every half hour.

[Muellar]

10 hours ago, Iceverge said:

Is your house completely in the middle of nowhere? 

 

Can you settle for a smaller supplier and buffer it with an on-site battery for peak loads? 

 

Would it be possible to organise the routing from a suitable transformer to your house yourself and just bury a chunky cable on your land? 

 

Can you move the house?

 

 

 

 

 

It is up on a hill but NIE have said they need to replace the whole transformer and want to charge me for that as opposed to just adding in my portion so they are playing a game in my view with me as i'd heard the transformer was up for replacement in any case. Now i've been looking into this seriously I'm tempted to go the CHP route that @SteamyTea mentions and using that at least for all the heating. To me it makes sense as winter months is when I would need the heating and is when PV output would be lowest, so having CHP doing that at least would be the way to go. If that get's me below a threshold then great, maybe NIE will see sense.

 

Moving the house isn't possible.

[dpmiller]

what size of supply was requested/ offered?

[Muellar]

3 hours ago, SteamyTea said:

You can do that yourself.  Try working out what you already use in your current home.

You can get into the nitty gritty by getting an energy monitor that logs data every Wh, or look at your smart meter data that averages every half hour.

 

I tried this and got myself in a pickle. Created various spreadsheets and am now completely confused by the whole thing which seems to be a bit of a dark art to me.

 

My current view though is given the feedback, is that i'm very tempted by the micro CHP route and getting a Calor gas tank put in. That way I transfer all the heating load and electricity gen to that particularly during the winter months when the PHPP calcs show the need. Once we are outside of Nov/Feb the heating need drops off, then CHP would decrease till we get sufficient from the PV/Batteries.

 

[Muellar]

5 minutes ago, dpmiller said:

what size of supply was requested/ offered?

 

hope you're sitting down....

 

engineer came up with peak demand of 40,000 watts, so suggested a 3 phase supply of 41 kVa.

 

I'm being told that I can have all the supply needed but as a single phase and not three phase supply. I reckon this is why the cost is as high as it is.

[saveasteading]

17 minutes ago, Muellar said:

said they need to replace the whole transformer and want to charge me for that as opposed to just adding in my portion

OK that is normal. The project has gone for costing and been costed and sent to you. That person doesn't assess whether the installation would then, or may perhaps, be used to supply other customers.

You must assess the likelihood of this and ask them to charge you only a proportion.  A different party will decide.

Is it likely?

If not, then it will be all your cost.

 

I've done this successfully for a 200k transformer, which very clearly was oversized and would be used again....and it was. But I think we engaged a specialist.

[jack]

What are you running that could possibly consume 40 kW given you're talking about a max 7 kW heating system?

 

Are you planning something like a 22 kW charger for a car?

[Conor]

36 minutes ago, Muellar said:

 

hope you're sitting down....

 

engineer came up with peak demand of 40,000 watts, so suggested a 3 phase supply of 41 kVa.

 

I'm being told that I can have all the supply needed but as a single phase and not three phase supply. I reckon this is why the cost is as high as it is.

That's crazy. With ashp, car charger, PV and induction hob, ours comes in at less than 20kW. And that's before you apply diversity. Give your engineer a boot up the hole.

 

Go back and ask NIE what they can provide from the existing transformer and work from there.

 

Otherwise, you will (rightly) have to stump for the upgrade.

[Iceverge]

41kVa is a lot. 

 

We were given the option of 16 or 12kVa. 

 

6 kVa would probably have done us. 

 

I would enquire what they can do with the existing transformer too. 

 

I bet that if it's even 1kVa you could make it work with some diligence. 

 

 

 

[saveasteading]

1 hour ago, jack said:

that could possibly consume 40 kW given you're talking about a max 7 kW heating system?

We wanted 3 phase because it was adjacent. £40k upgrade. Fortunately someone explained that the existing transformer provided plenty. 

That is for a big house, all electric.

That probably applies in this case.

[ProDave]

1 hour ago, Muellar said:

 

hope you're sitting down....

 

engineer came up with peak demand of 40,000 watts, so suggested a 3 phase supply of 41 kVa.

 

I'm being told that I can have all the supply needed but as a single phase and not three phase supply. I reckon this is why the cost is as high as it is.

So based on that you requested a 40KVA 3 phase supply and they came back with the big quote?

 

NOW go back and ask what you could have without major network upgrades?  In my case the answer was 12KVA single phase which ended up costing me £1K and has proved totally adequate.

 

If I really needed 3 phase here, there would be at least half a mile of single phase 11KV overhead line to upgrade to 3 phase then a 3 phase transformer to install.  That is likely where you get the silly high prices.

[Muellar]

33 minutes ago, ProDave said:

So based on that you requested a 40KVA 3 phase supply and they came back with the big quote?

 

NOW go back and ask what you could have without major network upgrades?  In my case the answer was 12KVA single phase which ended up costing me £1K and has proved totally adequate.

 

If I really needed 3 phase here, there would be at least half a mile of single phase 11KV overhead line to upgrade to 3 phase then a 3 phase transformer to install.  That is likely where you get the silly high prices.

 

I assume so as the engineer did all the dealings. I've seen he's said that NIE will want to upgrade the transformer to a 50kVA regardless of what we want as it's currently at capacity.

 

He said that a home such as ours from his experience would need 35-40kVA and we can have that but as single phase, not 3 phase.

 

My conclusion is that NIE are holding a gun to my head now as they want me to pay for a transformer upgrade even though i'll only be 1 of say 20 properties drawing off it of which several are farms with milking parlours!

 

[Muellar]

1 hour ago, Conor said:

That's crazy. With ashp, car charger, PV and induction hob, ours comes in at less than 20kW. And that's before you apply diversity. Give your engineer a boot up the hole.

 

Go back and ask NIE what they can provide from the existing transformer and work from there.

 

Otherwise, you will (rightly) have to stump for the upgrade.

 

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.