Green / Eco-Friendly

Solar + Battery for new construction off the grid - feasible? Possible?

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  • Jul 16th, 2017 9:55 pm
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I'm in a somewhat rural location and put in geothermal (I also have microFIT solar). In hindsight I probably would do propane heating rather than geothermal.

For off the grid solar I'd probably want a propane back-up generator which increases the cost. Geothermal has a LARGE start-up power requirement so you'd require a fairly large stand-by generator.

Propane is also good for cooking, fireplace, BBQ, clothes dryer. Possibility of costs going down in the future if they start supplying liquified natural gas to residential customers.
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JWL wrote:
Mar 26th, 2017 6:43 pm
I'm in a somewhat rural location and put in geothermal (I also have microFIT solar). In hindsight I probably would do propane heating rather than geothermal.

For off the grid solar I'd probably want a propane back-up generator which increases the cost. Geothermal has a LARGE start-up power requirement so you'd require a fairly large stand-by generator.

Propane is also good for cooking, fireplace, BBQ, clothes dryer. Possibility of costs going down in the future if they start supplying liquified natural gas to residential customers.
Do you mind me asking how you like the geothermal and any pros/cons you find with it? Also curious, sounds like several have significant electrical consumption for geothermal to run. Do you find that as well (microFIT solar aside).

Thanks!
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paullyn59 wrote:
Mar 26th, 2017 11:50 am
Mine is only 3500sq.ft & use 72KW average @ 72 degrees from December - March since 2006 install. Have you ever compared your before Geo & after Geo hydro usage?
I put geothermal in as soon as I bought the house before I moved in so I never had a hydro bill before hand. The prior owner had two seperate oil furnaces installed and said he used ~$4000 of oil per winter.

I know part of my house has insulation problems. Part of my house was built in 1860 and a 3000 square foot extension put into it in 1999. The 1860 portion is colder despite receiving more air flow from the furnace and that roof line melts quickly in comparisson to the additions roof line. This winter I beefed up the insulation to an r50 in the old side however that didn't really change anything.

My summer bills are INSANELY cheaper than my winter bills so I also assume something is wrong with the efficency of my geothermal system. I've disabled the ability to have my auxiliary heat come on and the regular geothermal has no problem keeping the house at 72.

I know my system is saving me money in comparison to the oil that was installed before but not enough to justify the 40k I spent on the system.
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Bawler wrote:
Mar 27th, 2017 9:57 am
I know my system is saving me money in comparison to the oil that was installed before but not enough to justify the 40k I spent on the system.
That sucks :(
Building science has advanced quite a bit, today we can design a house in software, calculate its heating/cooling requirements and add insulation virtually to see the cost/benefit ratios. Also geothermal is no longer cost effective, especially with ductless and ducted minisplits.
It really comes down to cost effective insulation levels and air tightness, a well designed house in most climates can get away with electric only heating, though this is still a waste since a modern minisplit can have a COP of 2-3 (200-300% efficiency).
OP, its never cheaper to make an efficient house then at the design stage, retrofitting is a ton of labour and often materials, houses can have lower heating requirements then just the electricity used for a geothermal system.
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Quentin5 wrote:
Mar 27th, 2017 10:12 am
That sucks :(
Building science has advanced quite a bit, today we can design a house in software, calculate its heating/cooling requirements and add insulation virtually to see the cost/benefit ratios. Also geothermal is no longer cost effective, especially with ductless and ducted minisplits.
It really comes down to cost effective insulation levels and air tightness, a well designed house in most climates can get away with electric only heating, though this is still a waste since a modern minisplit can have a COP of 2-3 (200-300% efficiency).
OP, its never cheaper to make an efficient house then at the design stage, retrofitting is a ton of labour and often materials, houses can have lower heating requirements then just the electricity used for a geothermal system.
I know. They're still in early design and layout, not yet close to engineering or mechanical drawings. Kind of waiting at this point.

In a large house with many rooms, is it really possible to go ductless and have minisplits everywhere? I'm having a hard time picturing it.
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joey003 wrote:
Mar 27th, 2017 10:19 am
I know. They're still in early design and layout, not yet close to engineering or mechanical drawings. Kind of waiting at this point.

In a large house with many rooms, is it really possible to go ductless and have minisplits everywhere? I'm having a hard time picturing it.
Ducted minisplits will work. This is actually a problem in efficient houses, many have 10-15K 99% design loads and you can't get gas furnaces that operate at such low loads, manufacturers don't produce them. Various options such as hydronic heating, locking out high fire on dual stage furnaces, open concept design and supplemental baseboard heating are among the solutions employed. Often people just leave the doors to bedrooms open during the day to prevent heat stratification.
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Bawler wrote:
Mar 27th, 2017 9:57 am
I put geothermal in as soon as I bought the house before I moved in so I never had a hydro bill before hand. The prior owner had two seperate oil furnaces installed and said he used ~$4000 of oil per winter.

I know part of my house has insulation problems. Part of my house was built in 1860 and a 3000 square foot extension put into it in 1999. The 1860 portion is colder despite receiving more air flow from the furnace and that roof line melts quickly in comparisson to the additions roof line. This winter I beefed up the insulation to an r50 in the old side however that didn't really change anything.

My summer bills are INSANELY cheaper than my winter bills so I also assume something is wrong with the efficency of my geothermal system. I've disabled the ability to have my auxiliary heat come on and the regular geothermal has no problem keeping the house at 72.

I know my system is saving me money in comparison to the oil that was installed before but not enough to justify the 40k I spent on the system.
Damn mine was only $18,000 for a 3 ton horizontal system. Duct work was not changed so it isn't as efficient as it could be but made the install cheaper. No rebates available in 2006 when we installed. Hydro usage was the exact same pre/post geo so heat and AC were "free" compared to oil. which is why I asked about yours. Wondered if we were an anomaly. Think the geo hot water savings for 7 - 8 people was huge. Old 23 year old oil furnace must have used a lot of electricity too.

Your winter/summer usage is not much different that mine. Last summer was about 32KW & 40KW in 2015. From what I was told, if your system is not trying to access backup heat too often then it is sized appropriately. Mine goes to back up during middle of the night, rarely during the day. Compare to when you don't use AC, not much difference because lose hot water savings.
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paullyn59 wrote:
Mar 27th, 2017 12:51 pm
Damn mine was only $18,000 for a 3 ton horizontal system. Duct work was not changed so it isn't as efficient as it could be but made the install cheaper. No rebates available in 2006 when we installed. Hydro usage was the exact same pre/post geo so heat and AC were "free" compared to oil. which is why I asked about yours. Wondered if we were an anomaly. Think the geo hot water savings for 7 - 8 people was huge. Old 23 year old oil furnace must have used a lot of electricity too.

Your winter/summer usage is not much different that mine. Last summer was about 32KW & 40KW in 2015. From what I was told, if your system is not trying to access backup heat too often then it is sized appropriately. Mine goes to back up during middle of the night, rarely during the day. Compare to when you don't use AC, not much difference because lose hot water savings.
Mine is a 5 ton unit. The unit itself was $9-10k and the rest was the actual trenching as well as SOME duct work.

My geothermal uses 3600-4000watts while in stage 1 or 2 and for most cold days it'll stay on near 24 hours.

Depending on your thermostat you can actually disable the ability to call for aux heat until a certain temperature. I keep my thermostat at 72 and the lowest I've ever seen it go with only using geothermal is 71 on the cold cold -30 Celsius nights but the aux will only kick in if the thermostat gets below 65.
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joey003 wrote:
Mar 26th, 2017 7:44 pm
Do you mind me asking how you like the geothermal and any pros/cons you find with it? Also curious, sounds like several have significant electrical consumption for geothermal to run. Do you find that as well (microFIT solar aside).

Thanks!
We have no issues with the system heating and cooling the home. It runs much longer than a normal furnace/AX because it heats/cools "less". This can be better for air circulation in the home and dehumidifying in the summer.

The main issue is with cost. Electricity is more expensive in rural areas (some of this is fixed cost which you are stuck with whether you go geothermal or not) and has gone up quickly in Ontario. Of course if you were off the grid, this is a non-issue.
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JWL wrote:
Mar 29th, 2017 6:42 am
We have no issues with the system heating and cooling the home. It runs much longer than a normal furnace/AX because it heats/cools "less". This can be better for air circulation in the home and dehumidifying in the summer.

The main issue is with cost. Electricity is more expensive in rural areas (some of this is fixed cost which you are stuck with whether you go geothermal or not) and has gone up quickly in Ontario. Of course if you were off the grid, this is a non-issue.
On the plus side I'll be saving close to $2k a year because of wynne's 25% off hydro in a bid to buy back votes
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JWL wrote:
Mar 29th, 2017 10:37 am
I think you mean deferring (and paying interest on) in a bid to buy back votes.
At this point it's all just a drop in the bucket. The liberals have put our province over the barrel so hard.

Hopefully the rest of Canada is saving money to bail us out because we're too big to fail.
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JWL wrote:
Mar 29th, 2017 6:42 am
We have no issues with the system heating and cooling the home. It runs much longer than a normal furnace/AX because it heats/cools "less". This can be better for air circulation in the home and dehumidifying in the summer.

The main issue is with cost. Electricity is more expensive in rural areas (some of this is fixed cost which you are stuck with whether you go geothermal or not) and has gone up quickly in Ontario. Of course if you were off the grid, this is a non-issue.
Not that it's for me at this time, but one thing I do love about what I've read with geothermal is that you don't really pump very hot air to bring a temperature up to a certain level or blast very cold air to bring it down. It sounds like it keeps moving air and only heats/cools in smaller variations to reach the desired level. Is that correct?
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joey003 wrote:
Mar 29th, 2017 12:53 pm
Not that it's for me at this time, but one thing I do love about what I've read with geothermal is that you don't really pump very hot air to bring a temperature up to a certain level or blast very cold air to bring it down. It sounds like it keeps moving air and only heats/cools in smaller variations to reach the desired level. Is that correct?
Generally yes. Some people find the air pumped in the winter coolish because it is only a bit warmer than the ambient temperature but moving so it actually feels cooler.
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joey003 wrote:
Mar 26th, 2017 6:21 pm
Yeah - no gas service at all.
I have one of these: http://ibcboiler.com/ibc-products/vfc-15-150/

They're rated for both propane and NG. Of course, it is a PITA to get propane schlepped in, but it is certainly far more economical than electricity. Bonus, as already mentioned, you can cook, dryer, etc with it as well.

Also, with an ERV, you could possibly do away with humidifier/dehumidifier as well (I'm counting on it!). That said, air-tightness is a must.

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