100% off grid?

[newhome]

33 minutes ago, jack said:

 

ASHPs, in contrast, can be done for as little as £2k installed, if you're willing to do some of the work yourself.

 

Yep, if you are good at DIY that's probably the way to go even if it means you don't get the RHI. If you're not it seems to come down to whether you can get someone do it, regardless of whether it's MCS or not. I have only managed to get a single quote (for 14.6k). That's RHI eligible. Even if that's the going rate I would like a second quote to validate this. No one here seems remotely interested in doing it. 

[scottishjohn]

24 minutes ago, Onoff said:

 

I don't want to take this off track but is that a viable swap out for an oil boiler in a draughty old house. At that sort of figure I might well consider it.

surely money would be better spent in wrapping the house in insulation first  to drop the energy requirement .

If its a BIG old house with lather +plaster  and high ceilings ,

you could always bring your rooms in by 6" on each wall and make an air tight insulated house inside that house by making stud walls + new insulated ceilings +vapour barriers to seal it all 

seen that done very effectively in a big house --no demolition just all new walls and new wiring etc ,dead easy to do while you live in it 

then the money you save on running the house will pay for the ASHP

just a thought if its BIG old house

no point in ashp till house is at least have decent thermal wise

 

Edited December 3, 2018 by scottishjohn

[newhome]

16 minutes ago, Onoff said:

 

I don't want to take this off track but is that a viable swap out for an oil boiler in a draughty old house. At that sort of figure I might well consider it.

 

Guy at work has accepted a quote for an ASHP in a draughty old house (MCS install so more expensive). The heat pump needs to have a larger capacity than many on here to deliver the sort of temps needed for high temp rads (and factor in the heat loss) but as long as it's sized correctly it should work I guess. His is sized at 16kw.  @PeterW contacted these guys and said that they sounded reasonable enough and they sell some relatively high capacity heat pumps as supply only. 

 

https://www.ebay.co.uk/str/Cool-Energy-Shop?_trksid=p2047675.l2563

 

You could fit the solar thermal at the same time . 

 

[scottishjohn]

49 minutes ago, jack said:

 

The main thing that puts people off GSHP is just cost. It more or less can't be done properly for less than £10k, and for most it'll cost more like £15k+

 

ASHPs, in contrast, can be done for as little as £2k installed, if you're willing to do some of the work yourself.

not a hope in hell to do a GSHP for 10k --borehole  or holes will be more than that . and if you thinking slinkys  you need a lot ground   for that and trench type is right way not slinkys --if contractor quotes for slinkys --find one that knows what he is doing

I could be wrong but i have not seen a GSHP pump unit for under 10K and if you get sizing wrong   it will not work .

same goes for bore hole --you try and get someone to guarantee what depth hole you need --they won,t do it --they will just say they can,t be sure how much heat till it dug + tested and you might need another one .

I looked at that long time ago   and discounted it due to possible variances in ground which affects how much heat you get  and no warranty from contractor as to how much drilling would cost --and that was 3 different quotes i asked for --all said the same .

now if you got a nice boggy field or a lake  --that is perfect for trench type GSHP --- any way you go get your quotes and you will see

the reason why the RHI is so big for GSHP  is the price it costs to do it --

just no need for GSHP in uk with the winter temps we get .

 

[epsilonGreedy]

Not sure where this thread is heading.

 

Home generated KwH are precious and costly to store, surely the OP should drop in an LPG tank for space and hot water heating. His off grid electrical requirement would then be scaled to the worse case winters day demand for all led lighting, TV, central heating pumps and white appliances which should not be a scary number.

 

Drawing from memory on my boating knowledge... £3k for a 5KVH diesel generator,  wet acid batteries 1000 12v amp hours for say 4KwH of usable capacity = £1400 from Halfords then round that off with a nice deluxe Victron invertor/charger for £1500.

 

I know such a scratch design needs improvement but my intention is to show this problem can be solved when the alternative is a £40K grid hook up cost.

[Jeremy Harris]

5 minutes ago, scottishjohn said:

not a hope in hell to do a GSHP for 10k --borehole  or holes will be more than that . and if you thinking slinkys  you need a lot ground   for that and trench type is right way not slinkys --if contractor quotes for slinkys --find one that knows what he is doing

I could be wrong but i have not seen a GSHP pump unit for under 10K and if you get sizing wrong   it will not work .

same goes for bore hole --you try and get someone to guarantee what depth hole you need --they won,t do it --they will just say they can,t be sure how much heat till it dug + tested and you might need another one .

I looked at that long time ago   and discounted it due to possible variances in ground which affects how much heat you get  and no warranty from contractor as to how much drilling would cost --and that was 3 different quotes i asked for --all said the same .

now if you got a nice boggy field or a lake  --that is perfect for trench type GSHP --- any way you go get your quotes and you will see

the reason why the RHI is so big for GSHP  is the price it costs to do it --

just no need for GSHP in uk with the winter temps we get .

 

 

 

I priced up a Kensa GSHP installation back when we were still looking at options.  The heat pump and installation kit was around £4.5k, the borehole, including collector piping was about another £5k and the antifreeze was around £400.  There would have been around another £500 of ancillary stuff I expect.

 

Opting to use a vertically trenched slinky collector was a lot cheaper, under £3k IIRC, but would have been problematic in terms of the impact it would have had on the foundations for our retaining wall.

 

I think @jack's figures are about right for a GSHP/ASHP in terms of relative cost, and they certainly tally with the cost comparison I did.

[Jeremy Harris]

5 minutes ago, epsilonGreedy said:

Not sure where this thread is heading.

 

Home generated KwH are precious and costly to store, surely the OP should drop in an LPG tank for space and hot water heating. His off grid electrical requirement would then be scaled to the worse case winters day demand for all led lighting, TV, central heating pumps and white appliances which should not be a scary number.

 

Drawing from memory on my boating knowledge... £3k for a 5KVH diesel generator,  wet acid batteries 1000 12v amp hours for say 4KwH of usable capacity = £1400 from Halfords then round that off with a nice deluxe Victron invertor/charger for £1500.

 

I know such a scratch design needs improvement but my intention is to show this problem can be solved when the alternative is a £40K grid hook up cost.

 

 

Halfords batteries won't last a year in an off-grid home application, I'm afraid, as even their supposed "deep discharge" batteries have a really short cycle life, around 200 to 300 cycles is typical..  There are really only a couple of proven off-grid lead acid battery systems, and that's either to opt to fit Rolls wet batteries, as Paul Camilli uses, or to use forklift battery packs.  Lots of off-grid people swear by fork lift packs, as they are often available at a reasonable price.  The key to making them last seems to be to never run them below about 75% to 80% SoC, to always control the charge regime carefully to minimise gassing and to regularly keep them topped up.

 

The need to never deeply discharge lead acid batteries, even fork lift or Rolls cells, means that the installed capacity has to be around five times the usable capacity.  It's tough to get below about 5 kWh per day consumption when off grid, so that implies having around 25 kWh installed capacity as a bare minimum, more if you want to live with all modern comforts.  A fork lift pack will anything from about 600 Ah to 1000 Ah at 48 V, so between 28.8 kWh and 48 kWh installed capacity, around 5.8 kWh to 9.6 kWh usable capacity, and cost somewhere between £2500 and £3500.  With luck, and careful looking after, they should last ten years to fifteen years.  One challenge with them is the weight and getting them to where you need to put them, as even the individual cells in a forklift pack are damned heavy to shift.

[scottishjohn]

59 minutes ago, JSHarris said:

 

 

I priced up a Kensa GSHP installation back when we were still looking at options.  The heat pump and installation kit was around £4.5k, the borehole, including collector piping was about another £5k and the antifreeze was around £400.  There would have been around another £500 of ancillary stuff I expect.

 

Opting to use a vertically trenched slinky collector was a lot cheaper, under £3k IIRC, but would have been problematic in terms of the impact it would have had on the foundations for our retaining wall.

 

I think @jack's figures are about right for a GSHP/ASHP in terms of relative cost, and they certainly tally with the cost comparison I did.

I just went to kensa site and filled in the rough quote guide with details  150sgm floor area and new build house--came out at £25.6k --i knew you were not even close to proper price for gshp 

[Guest Alphonsox]

15 minutes ago, scottishjohn said:

I just went to kensa site and filled in the rough quote guide with details  150sgm floor area and new build house--came out at £25.6k --i knew you were not even close to proper price for gshp 

 

JSHarris pricing looks on the mark to me. Very similar to the pricing we came up with when we were looking.

https://www.kensaheatpumps.com/wp-content/uploads/2016/05/Heat-Pump-Unit-Price-List_print__V1.pdf

 

By the way the Kensa calculator is extremely pessimistic and doesn't have options that come close to a Passive spec house. It over-specs my requirements by a factor of 4.

[jack]

28 minutes ago, scottishjohn said:

I just went to kensa site and filled in the rough quote guide with details  150sgm floor area and new build house--came out at £25.6k --i knew you were not even close to proper price for gshp 

 

Is there any particular reason for the constant stream of aggressiveness?

[jack]

I just searched ground source heat pump installation costs. First page of results lists prices as things like £13k, £13-20k, and £12.5k. 

 

I said it couldn't be done for less than £10k and that it was more likely to exceed £15k. Not sure how anything you've said since shows that those numbers are unreasonable.

[Jeremy Harris]

52 minutes ago, scottishjohn said:

I just went to kensa site and filled in the rough quote guide with details  150sgm floor area and new build house--came out at £25.6k --i knew you were not even close to proper price for gshp 

 

 

I had three or four long phone conversations with them, and had a firm quote.  Same goes for the borehole collector, I had a firm price from our borehole drilling company.

 

So, the prices I quoted were real, firm, quotes from two companies, not some mythical estimate from a website. 

[Ed Davies]

I'm doing a “no-combustion” house. Meaning it doesn't burn stuff like wood, oil or gas and doesn't use mains electricity (a lot which comes from burning stuff).

 

Well-insulated not-so-large house (~= 0.1 W/m²·K, good airtightness) with sufficient but not excessive windows.

6 kW of PV.

10 kWh of lithium iron phosphate batteries.

6 or 8 20x47 mm solar thermal panels (I've bought 8 but may only be able to fit 6 or 7 while allowing fire escape from the two bedrooms).

Probably a small wind turbine but not decided what sort yet.

Large (10m³) thermal store inside the house for space heating bordering on inter-seasonal storage.

 

I'm a big believer in mixing wind and PV. There are lots of dull days and lots of lulls in the wind [¹] but it's very rare for a dull lull to last more than a day or so.

 

Will that be sufficient “without a very large compromise in terms of living”? I hope so but ask me in a few year's time. I suspect 9 months of the year will be easy, December, January and February will be comfortable with a bit of forethought - look at the forecast and the state of charge before doing washing or cooking something that takes a long time. We'll see.

 

OK, a backup generator's likely but I'd consider it a fail if it's needed more than a handful of times a year.

 

[¹] Although I'd have made a bit more progress on the build this year if there'd been a few more lulls.

Edited December 3, 2018 by Ed Davies

[Declan52]

31 minutes ago, Ed Davies said:

I'm doing a “no-combustion” house. Meaning it doesn't burn stuff like wood, oil or gas and doesn't use mains electricity (a lot which comes from burning stuff).

 

 

Do you include the wife in that  category as mine uses the smoke alarm as the timer. 

[Ed Davies]

There are some things to be said for being single.

[Onoff]

7 minutes ago, Declan52 said:

Do you include the wife in that  category as mine uses the smoke alarm as the timer. 

 

Yours too! My kids show a Pavlovian response when ours goes off and start salivating.

[newhome]

3 hours ago, scottishjohn said:

surely money would be better spent in wrapping the house in insulation first  to drop the energy requirement .

 

Ironically if your house is poorly insulated you stand to gain more if you go the MCS / RHI route. The guy I know with a draughty house is having external insulation fitted to his walls, but not before his ASHP is installed and he get the RHI payments coming in. 

[scottishjohn]

11 hours ago, newhome said:

 

Ironically if your house is poorly insulated you stand to gain more if you go the MCS / RHI route. The guy I know with a draughty house is having external insulation fitted to his walls, but not before his ASHP is installed and he get the RHI payments coming in. 

you are correct ,but it must meet certain level to even qualify for RHI to start with 

same as fitted solar thermal --if you doing ASHP your rate will drop if you declare solar thermal .

on a very good house its hardly worth going RHI  ,if you fit yourself savings there will far out weigh RHI payment

[newhome]

1 hour ago, scottishjohn said:

on a very good house its hardly worth going RHI  ,if you fit yourself savings there will far out weigh RHI payment

 

Yep that's true. I can't fit myself however so I'm probably on the cusp of RHI being more favourable than getting a non MCS person to fit a cheap ASHP as long as I get metering for performance rather than metering for payment. Needs some sums done though. This house isn't passive by any means although it's not terrible either, but alongside that the size of the house helps with the RHI payment. 

 

[Ed Davies]

Something else: to have anything like reliable power you'll need a mix of sources, storage and some way to control what power is used when. This is not terribly difficult but not the sort of thing that typical electricians, etc, have any clue about. Individual suppliers of PV, wind turbines, batteries, inverters and so on will tell you about their individual bits but none of those will have the “big picture” of how your system operates. You'll need one person who does have that big picture and also understands the details of how to set up each of the parts so they work together properly. There are very few people with a suitable track record to qualify them for that job so your best bet is for that person to be you.

 

I'm thinking here of a chap in Aberdeenshire who built a very nice wooden house which was off-grid for very much the same sort of connection-cost reasons. He had a mix of sources of information with different people commissioning different parts and giving conflicting advice. For reasons which aren't clear to me he was advised by one supplier to remove one of the diversion dump loads on his battery and for other reasons which are also unclear this resulted in a fire in his utility room.  Luckily it was contained and the damage was fairly limited. But it was evident from his description that he didn't really understand quite basic aspects of the system so was easily mislead.

[epsilonGreedy]

On 03/12/2018 at 18:42, JSHarris said:

Halfords batteries won't last a year in an off-grid home application, I'm afraid, as even their supposed "deep discharge" batteries have a really short cycle life, around 200 to 300 cycles is typical..  There are really only a couple of proven off-grid lead acid battery systems, and that's either to opt to fit Rolls wet batteries, as Paul Camilli uses, or to use forklift battery packs.  Lots of off-grid people swear by fork lift packs, as they are often available at a reasonable price. 

 

 

I agree, I was just illustrating minimum set up costs for a "scratch design" system. Your £2800 estimate for batteries is better. "Golf Cart" batteries are often mentioned in sailing forums though this could be an American focus.

 

On 03/12/2018 at 18:42, JSHarris said:

The need to never deeply discharge lead acid batteries, even fork lift or Rolls cells, means that the installed capacity has to be around five times the usable capacity.

 

 

I have heard about a requirement for periodic deep discharge to restore the surface of plates, even so this does not change the capacity planning maths.

 

On 03/12/2018 at 18:42, JSHarris said:

It's tough to get below about 5 kWh per day consumption when off grid, so that implies having around 25 kWh installed capacity as a bare minimum, more if you want to live with all modern comforts.

 

 

I suppose it depends on whether the diesel generator kicks in to handle high load periods. This then leads onto another debate about providing enough charging load to provide a healthy level of work for the generator engine as diesels do not like prolonged low loads. The problem is compounded by the fact that wet acid batteries soak up amps at a much lower rate when topping up from 85% to 100% charge.

 

If I was the OP I would be looking at a large battery and invertor capacity to handle max load and a smaller generator capable of generating the worst case winter whole day consumption over 6 hours. Couple that with 4 Kw of PV and the generator might not kick in for 6 months of the year.

 

The notion of UFH via air source powered from off grid electricity in anything less than a passiv house sounds a little nutty to me, though this is based on intuition and not maths. 

[Ed Davies]

4 hours ago, epsilonGreedy said:

Couple that with 4 Kw of PV

kW.

 

But why so small? By my calculations 6 kW is about the minimum for one person who doesn't use a lot of electricity. The marginal cost of PV these days means it's silly to scrimp on it so it seems sensible to try to at least make your renewable generation over the winter average at least your consumption then leave any generator to deal with the case where there's a long lull. In other words, use the generator to cover short-falls in battery capacity rather than short-falls in average generation.

 

4 hours ago, epsilonGreedy said:

The notion of UFH via air source powered from off grid electricity in anything less than a passiv house sounds a little nutty to me

 

Me too. The OP says “100% off grid” but nothing about the stated circumstances indicate they want more than just electricity. It's a matter of taste whether you consider, e.g., oil deliveries being “on grid” but just to save the cost of an electrical connection an oil boiler seems the obvious means of space and DHW heating. If you have sufficient PV and/or wind for the winter then there should be plenty of spare for the shoulder months (spring and autumn) so oil consumption should be pretty low.