ouch "solar cooks greenie in his bed!"

[BruceM]

RCAvictim- I like the 2x shop to house size.  There is no such thing as a shop too big. The solar panels can be seen from behind my house, by the clothes line,  just not by the casual "looky lou" coming up to the house on the driveway or by the front of house or shop.  The house is secluded in a hollow, so it's hard to case the joint- you can't see if anyone is home by car.

Double walled construction is fairly common in eastern Canada around the great lakes, near where I grew up.  The same principals that work in an area with several weeks at -27F, also work well in more moderate climates.  My total wall thickness is 13.5". By not having the inside studs touch the outside studs (staggered location is preferred), and a gap between sill plates, you eliminate thermal bridging of studs- which are typically less than R-1 per inch.  My outer wall is 6", the inner 4", both batts are 6".  The extra thick walls also allow for 4" of blue board (extruded polystyrene) between stem wall and slab. (The two walls bridge this foam, the inner wall thus is fastened to the warm slab and there is not a cold spot.)  This works wonders for reducing slab thermal losses, according to the computer models  I used, and according to my propane bill.   My rooms are very uniform in temperature, no colder slab near the outside walls. No extra thermostats, zoning and extra pumps are needed for my small (1100 SF) house.

Where it's practical to do so,  a well insulated concrete slab of 5-6" inside of a superinsulated home, alone with 5/8" sheetrock provides an enormous amount of thermal mass, for the least additional cost.  Even if I had to do a lot of fill and tamp, I'd do it to keep the huge slab mass.   For radiant slab, I like the method of 3/8" rebar on 14-16" centers, with Pex zip tied to the rebar (on plastic chairs over foam board).  1" Pex to manifolds can be run under the rebar.

On some sites, it's just not practical to do a slab.  Also, for some contractors here, only a raised wood floor over crawlspace is practical- they are incapable of planning ahead accurately even with good floor plans and concrete is too unforgiving.  You have to work with the resources you have.  

[Fat Charlie]

I'm just researching solar for our retirement home, and I am thinking that for right now...I would be an early adopter...where the roi is better for everyone(parts suppliers) in the loop but me.

So far my research tells me that there will be a quantum leap, in the next 5 years that will change the economics. I would hate to find that my 25 year investment (before a net on my roi) 5 years from now will not be worth anything but recycle value. Sure I could continue to use the existing sys...but I find that on par with staying with a 486 running 3.1.

Lloyd

A 25 year investment is a 25 year investment.  This year's solar install may very well have no value in five years- if you want to sell the hardware.  But if it's still providing the power you specified then it still has just as much worth as the day it first came online.  It either powers your house or it doesn't, and hypothetically available future technology won't change the fact that your system powers your house.  

Yes, the systems are going to get better and cheaper.  So you get the best that you can when you actually do it.  Unless the XYX 4300 solar panel is due out in a few months, get the damn XYZ 4200s that are available today and don't worry that at some unspecified point in the future you could have gotten more bang for the buck.  

To paraphrase Donald Rumsfeld, "You go off the grid with the systems available, not the systems that will be available five years from now."

[Lloyd]

A 25 year declining value investment...is a real misnomer...being propagated by the solar equipment sales force.

How many actual PV panels are now 25 years old....none...the expected life value is an estimate...no real numbers yet.

How many peeps are living in the same house they were 25 years ago?

How many peeps will be living in the same house 25 years from the date of commissioning the Solar install?

Now five years later I'm in the market for a new house. My options are three identical homes for sale in the same neighborhood, built by the same builder, of similar plans, and upkeep.

house 1. No Solar installed.

house 2. A five year old solar install that is old technology...I'll bet this house won't sell for a price =to #1 plus the un-amortized costs of the solar install.

house 3. A new solar install with the latest greatest PV technology, that is 1.5 times more efficient, and dollar for dollar cheaper then the old technology. I'll bet this house will only sell at a marginally higher value then #2. certainly not for the same price as #1, plus the costs of the solar install.

Which house am I going to buy, which house are you going to buy?

The best bargain is buying another persons mistake for pennies on the dollar.

remember, you get no roi until after 25 years, on most systems...unless you are the diy'er/bargain hunter, then that may effect the market value of the house to a greater extent.

Lloyd

To paraphrase Donald Rumsfeld, "You go off the grid with the systems available, not the systems that will be available five years from now."

I go off grid for a reason...that is factored by noi...going off grid at a cost of power generated 3 time  that which I can buy from the grid isn't an investment...that's a mistake....everyone loves to buy for pennies on the dollar.

[Jedon]

I'm off the grid due to location, and I'm hopefully at my final resting place so no selling. I totally agree that for most people, PV makes no economic sense and there are usually other reasons that make them feel good about it for one reason or another. I got mine from a guy who buys them up from foreclosures and then sells them for 1/2 retail.

That double wall building sounds like great engineering but wouldn't a technology like SIP's or ICF be cheaper and just as effective?

I live in the middle of nowhere, if strangers get past the dogs then I or the wife will be waiting with the shotgun. We are rarely both gone for long, like that sign says, protected by Smith and Wesson 4 days a week, you guess which days.

I'm hoping technology comes to the rescue with fuel cells, carbon nanotube batteries, 4G cell/LTE/whitespace internet etc to make power and communication cheaper and better. Not holding my breath for it to plow my road though :-D

[BruceM]

SIPs and ICF's are incarnations of insulated concrete forms or waferboard sandwich of foam, I assume. I haven't seen any in the R-39 range, but perhaps there are. Foam of a lesser R value will often perform better than bats where there are high winds, as most Tyvec jobs are poorly done.

Lots of ways to make a super insulated wall, but few are likely to be cheaper or simpler as just framing up a non-load bearing interior wall.  My helper and I did the second exterior wall in one afternoon.  There's this innovation called precut studs, and nail guns.

[Jedon]

I have learned to love the nail gun! The SIP panels are indeed foam sandwiches, 6" of foam with 3/4 OSB on either side and they get all precut so when they arrive on site they go up super quick, just tilt up and glue/nail, whole shell goes up in days. Material cost is higher, labor is lower, in your case doing stuff yourself it would cost more, in mine I helped so it was probably a wash. It is a little harder to run electrical etc but they come with pre-done chases. R39 would have to be 10" not 6" like I have, my climate isn't severe enough to warrant the extra cost.

[BruceM]

I can't work around or live inside with phenol-formaldehyde resins, so I'll never know if SIP would really save any money.  We had the whole house framed and trusses on in a week with just two of us. (A third guy for trusses.)  Plus an extra afternoon later for the interior-exterior wall.  I had a builder friend who wanted to be hired for the framing.  I said hell no, Bill, after all the suffering on the foundation and concrete work, framing is a party that's over too soon! 

The SIP walls should perform well thermally- no air infiltration into the styrene bead insulation, and no studs to make thermal bridges and reduce the overall R factor.  I think 6" of bead board is around R21, but I know that SIP wall will thermally outperform the heck out of a 6" framed wall with R-19 fiberglass insulation in the real world. 

[Jedon]

Sounds like you did it right, I'm just a young'un without any building experience so had to hire help. Indeed SIP walls outperform stud walls of the same R value by quite a bit but I would think your double walls are even better. I actually wanted to build a castle and have 3' thick walls with stone on the outside, foam in the center and traditional framing on the inside so I got thermal mass, insulation, and ease of interior installs all in one. Couldn't get the financing though and after building I can see why, it's tricky business!

[rcavictim]

Sounds like you did it right, I'm just a young'un without any building experience so had to hire help. Indeed SIP walls outperform stud walls of the same R value by quite a bit but I would think your double walls are even better. I actually wanted to build a castle and have 3' thick walls with stone on the outside, foam in the center and traditional framing on the inside so I got thermal mass, insulation, and ease of interior installs all in one. Couldn't get the financing though and after building I can see why, it's tricky business!

From an energy conservation perspective didn't you get that backwards?  You'd want the 3 foot of stone on the inside.  That would stay a constant temp year round due to it's mass.  The insulation system outside of that would keep the heat of summer and the cold of winter from modulating it.  You could add a solar thermal system which would pump heat into this stone mass when heat was available and needed to maintain indoor core temperature.

[Cornelius]

Yes, he got it backwards...

These days you want the thermal mass inside... (But in the future, do we want and need thick exterior walls for physical protection; that would depend on the mind, i think... )

[BruceM]

Yep, that's the bummer of stone or split face block (which I also like the look of); all that mass is outside the insulation envelope and does you no good at all, thermally. 

[cognos]

Just my experience...

This is my 26th year in my house. It was my first home, and even then, I meant it to be my last, and if all goes right, I should still be here for another 25 years or so. I was very young when I bought it, but i had a plan. Everything I do around the house is meant to decrease maintanance (as my physical ability to do it decreases with age) and energy costs looking forward (as I don't expect them to go down anytime soon...).

I have a 24 year old 20 watt solar panel. It charges my emergency battery back-up system that can power some lights and a TV/radio for a while. Saves me having to start the generator in a short power outage.
That solar panel still works as well as it did when I bought it, the plastic cover is still dead clear, still has good voltage and current under load. The only thing I've replaced was the aluminum mount - it was bent over in the Ice Storm of 1997, but the panel itself survived. Those in Southern Ontario/Quebec know of that which I speak... I've upgraded the inverter once, the charge controller is now a modern PWM unit, and changed the original deep-cycle boat battery (that worked great for 18 years!) for 2 AGM tel cells that are half the size and twice the capacity.

So ya, there are some old solar cells that still work, and some of us stay in our homes for 25 years... but it's rare... The guys I worked with thought I was crazy - they all switched house every few years. They'd no sooner get a handle on their mortgage, and it would be time to get a bigger one - mortgage, I mean... I never had a mortgage... I bought a cheap, fixer-upper on a fantastic lot. Really, I bought the place for the lot. That I could afford.

Of course - even 24 years ago, there was only science-fiction talk of powering one's house with solar. And one would have had to be a millionaire. If I remember correctly, that panel cost me $300 in 1986 dollars... and I only got it that "cheap" because a friend of mine worked for Bell Telephone, and they were ordering many of them... but I was an early adopter, and back then, I could afford it. Electricity was cheap in the past. In relative terms, it's still cheap. No way I'd get a payback on my solar panel - ever.

If I were to do it again - I'd build, not buy. I would've probably been farther ahead if I'd knocked down the house and built a new one, even with what passed for cutting-edge technology in 1984. I tell that to everyone who will listen - build a proper house! Don't buy the junk on the market in some subdivision! If you can't afford to do it now, wait until you can!
I've spent the last 26 years essentially re-building my home's 1970's technology - which was crap, and poorly-done at that. I've reinsulated, re-sided, rewired, replumbed, new floors, metal "lifetime" roof... and there's still a surprise or two left in the place, I think. But I have a fantastic site... and you know what they say about location...

In my new fantasy single-floor, ultra-low maintenance home, I'd use 10" SIPs, over a radiant-heat slab. There would be plenty of passive capacity built in, but I'd probably go geothermal for heating/cooling. With wood heat for backup and ambiance... and my 24 year old battery backup would find a place here, as well.

[Jedon]

Yes, he got it backwards...

These days you want the thermal mass inside... (But in the future, do we want and need thick exterior walls for physical protection; that would depend on the mind, i think... )

This is where I stole the idea from http://www.castlemagic.com/castleplansopen.html , I thought to frame out some of the interior since it's a pain hanging things on rock :-)
This guy does some awesome work http://www.castlemagic.com , perhaps in 15 years my current place will be the guest-house...

I totally agree about the quality of most spec home, they just don't care and cut so many corners.

[Lloyd]

http://www.enphaseenergy.com/products/moreinfo/enlighten.cfm Now here is a technology that in it's infancy that looks to improve many a PV installation. Coupled, with a new CPVhttp://www.energyboom.com/solar/new-technology-creating-waves-solar-industry technology, and we may start to see PV's that approach 30% efficiency, which is 2 times the current tech. I think it's way to early to adopt...but just one of the many changes coming.

I spent over 25 years in the housing industry, Building, Sales,and Banking. Barring the the last economic cycle, RE has an unmatched ROI, that includes those tract houses. Move up buying has led to many families generating wealth, they could have never done by working or saving.

Early adoption of Solar, is the single biggest threat to that wealth building process I see.

Sure some have found a way to minimize the losses but they still exist.

Take an average PV install with all the associated costs, lets say $65,000.00. In five years it saves $120 x 12mo x 5yr = $7200.00 dollars in money paid to the grid. Now lets take the same 65,000.00 invested in a simple conservative 5% compounded annual return x 5yr = $17,958.00 so in five years the solar loss is over 10k. Due to compounding the loss grows exponentially, the longer you own the system.

Lloyd

[cognos]

Yes, I've bought and sold many houses and multis and had a fair amount of success. But not my actual primary residence.

As an investment strategy, I never understood how buying a primary residence with an excess of borrowed money, then selling that same house at a profit when the market goes up, only to buy a more expensive house with a larger amount of borrowed money, made any sense to an average person with no other off-setting investments. You can't get the money out until you sell, and you'll still need somewhere to live... and if the market is in downturn when you need the cash, you're in deep trouble. I'm too conservative an investor for that - and I can't afford to lose principal.

I think the same about solar. Without subsidies, I can't see the economic sense in it where I live, where the grid is available, and I'm not wealthy enough to try to act that "green.". With an investment of that size in the PV system, I could invest many other things, and the money I made would pay my hydro bill and then some, and provide for my future... And the last time I checked, mutual funds have a very low risk of catching fire should they be installed improperly...

I think expensive government subsidies for wind and solar - buyback programs from private providers, in Southern Ontario - are terrible investments for the Ontario Hydro system... but that's just me, here.