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Old 10-29-12, 12:40 PM   #11
Daox
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If you're looking to use concrete you'll probably want to look into ICF (insulated concrete forms), but IMO the larsen truss is superior. You can make your wall as thick as you want. This allows you to get upwards of R60 walls which is what you'd want to get into the passive house realm.

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Old 10-29-12, 12:53 PM   #12
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how long can a passive house really go without sunshine?

yesterday it stopped raining and was a bit sunny here for 4 hours. That was the first sun in a week. It did little to heat my house up even though we have excellent exposure, overhangs and the such. The weather forecast is for rain till friday then cloudy. It's been crappy like this for almost 3 weeks now.

If I was going solar I'd be grid tied simply because the winter has so little productive days compared to the summer which can easily make an excess.
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Old 10-29-12, 12:58 PM   #13
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Thats a good question, but really probably too complex to answer. It really just depends on how you design it. If you worry about bad weather you could fairly easily add more southern glass and additional thermal mass to regulate thermal swings and cloudy weeks.
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Old 10-29-12, 01:37 PM   #14
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Everybody has good advise, Doax I was just reading up on ICF
I am going to contact a some what local supplier of them and get some prices.
http://www.cpci.ca/downloads/nationalinsulatedwall.pdf

From what i have read Solar Panels work fine in cloudy weather, Add more panels to bring your supply right up to where you need it, no problem with that. Once installed i will save $1200 to $1500 a year i would normally pay B.C Hydro.
I 'll spend money up front on a PV system, some battery storage ect.. I priced a 1100 watt PV system at $1400, piece of cake, i'll get 3 of them if needed and save bags of money compared to be hooked up to the grid. Its a win win being off grid, no Hydro bills and cheap as dirt acreage(comparatively)
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Old 10-29-12, 02:34 PM   #15
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my 45 watts(rated) of amorphous panels normally puts out 40 watts on a sunny day. Today they're putting out 6. You'd need an insane amount of panels to power your house on a cloudy day.
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Old 10-29-12, 02:55 PM   #16
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Quote:
Originally Posted by strider3700 View Post
how long can a passive house really go without sunshine?...
I have seen many studies on Passive Houses and heat coming in from the environment is one of may design criteria. There is also heat gain from living, even with 'green' appliances.

In areas where thermal input from the environment (usually solar) window location and size comes into play.

I have seen a study of a Passive House that was built in a particularly challenging micro-climate in Scotland (continual wind, no sun), where solar gain in the winter was insignificant, and window heat loss was substantially greater than their heat gain, so windows were minimized, and the highest performance windows were used. Wall insulation was maximized to balance internal heat gains.

Passive House designers use a very sophisticated spread sheet that includes all of these factors, and many, many more. The spreadsheet is called Passive House Planning Package (PHPP for short). You can buy it online, for $206, it is an incredible deal. The spreadsheet even considers the geometry of the house, since heat loss is directly related to surface area. So the package does not discourage high-surface area geometries, rather it calculates the other aspects (wall insulation being one) so that the house will meet Passive House criteria.

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Old 10-29-12, 03:00 PM   #17
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Quote:
Originally Posted by strider3700 View Post
my 45 watts(rated) of amorphous panels normally puts out 40 watts on a sunny day. Today they're putting out 6. You'd need an insane amount of panels to power your house on a cloudy day.
I agree - having panels is ok but when it's cloudy don't expect much power - a generator backup is essential (if you are off grid) unless you like candles!

Also bear in mind that batteries are both expensive (for the amount of storage you would need) and have a limited life. I've seen batteries abused and only lasting 2-3 years.

Bateries can last up to 10 years if well maintained but will need replacing. The more capacity the more expenseive.

Off grid is great but it isn't free. Just remember how much electric you could pay for with $15k which is what you'll need to spend on a decent capable solar system.

Remember too, many dull days = no power = need to use a backup = generator = fuel costs. Plus maintenance costs.

I love solar energy. It has its place and can save money but you need a balance and to be realistic.

I have about 1KW of panels, 980Ah batteries (24V) and a 4KW inverter. It's ok for general use in the house (lights/tv/fridge/sockets) but the washer, dishwasher and electric oven are connected to the grid supply. When I have full batteries I use solar. When they are exhausted I switch back to the grid and let them recharge off the panels (I don't use a generator).
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Old 10-29-12, 03:09 PM   #18
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Not sure what the problem is, must be your panels or my error.
I will post a link to some info on PV panels and cloudy day use.


After reading up on ICF's it appears the costs are more then i will be able to pay or willing to pay, giving the R value of them.
I will have to make it myself, cut out the middleman, either make a tilt up design (I know someone who will help who has poured them and put them up) or go with Concrete Block, poured foam filled with a plastered interior and 6-8 inch foam exterior wrapped and plastered with a dyed concrete or scratch coat and sealed.

If i do it myself the walls will get thicker and more insulation with the exterior walls and foam filled concrete heat adsorbing blocks.

I wonder if filling the blocks with insulation would be needed ? It would save money not to do it, if its not going to be that effective, in this design.

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Old 10-29-12, 10:25 PM   #19
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Its looking like PV panels make about 10% of the rated power on a cloudy day like a typical winter day that south western B.C gets for months at a time in the winter, Lots of cloudy wet weather over here from the end of January to march/April.
I will need about about 10,000 watts in PV panels and some battery storage too run the house. If the heat pump uses 750 watts i can make it work.
about $15,000 for the panels, inverters including a few grand worth of batteries.
I will have to buy the land (a semi isolated acreage) and build the house with $175,000. I am hoping to spend $75,000 on land and use the rest on building supplies and expenses.
The Cinder Block walls with foam/cement exterior is looking like the way i am going to go, with the relative ease of insulating it to my specs, combined with a lower cost as compared to tilt up or pre-fab ICF panels.

I still need to figure out the right material to break the thermal bridge between the foundation and the cinder block walls, I have seen a video of a air-filled concrete that is used on foundations of passive houses in the UK, it is full of voids that break the thermal bridge. I am beginning to recognize that i should have back up heat/ wood furnace, but i am not giving up. A lot of people do not have a large PV systems and are somewhat dissatisfied with it, 10,000 Watts should pull me threw a winter ?
What the _____ am i going to do with 10,000 watts of power in the summer ?? I can see the benefit of being grid tied if only to sell them the excess power.




Our solar panels are 14 Sungrid panels at 215W each giving a total potential output of 3010W (3.01kWp) The SAP 2009 annual yield was quoted at 2479kWh.
Quote from link:
So far as of 13 July 2012 we have already generated 1972kWh of electricity in one of the worst British summers since records began with the wettest April and June since 1910. Extrapolating the generation figures over the next few months we could well see a total for the year of 3000kWh.http://uk-solarpanels.blogspot.ca/20...1_archive.html

I found this video that is worth a watch, if you like 3 thousand watts of PV system.

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Old 10-29-12, 11:15 PM   #20
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Have you looked into the efficiency of solar heat collectors?

Not as sexy as PV, but you might get more heat energy per buck.

-AC

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