
The Zen of Passive Solar Heating Panel Design (2010) - mpatobin
http://www.iedu.com/Solar/Panels/index.html
======
samcheng
Here's the payout:

> This installation was completed in 2007 - and has been adequate to maintain
> the indoor temperature above 65°F/18°C since that time – even though outdoor
> temperatures in winter dropped below -20°F/-29°C and even though the nine-
> foot by nine-foot overhead door has been opened every morning and every
> evening.

> Before the end of 2009 the panels had saved more than their purchase price
> in fuel costs and the owner expects that the future savings will exceed the
> original cost of the entire structure. He told me he really likes starting
> every day (checking his livestock) in a nice warm truck.

~~~
themartorana
So what's stopping a setup like this becoming standard? It's obviously
generally superior, at least for new construction that's well-insulated.
Right?

~~~
maxerickson
They won't work very well when they don't have good southern exposure, they
won't circulate a lot of heat if you have rooms and doors.

Meanwhile, the direct operating costs for natural gas heat aren't all that
high.

~~~
Retric
Inserting something like this into the duct work of a normal heating or
cooling system is fairly simple. The real issue is they increase construction
costs and most buildings are built by people that don't use them. Further,
they don't look like something out of a Norman Rockwell painting.

~~~
andrewwhartion
> most buildings are built by people that don't use them

Having rented for the past 6 years in 4 different houses, I've become
convinced that this is one of the most significant factors for why so many
house aren't enjoyable to live in.

Even if the overall design and layout of the house is good (I'm talking about
the Christopher Alexander sense of good design), there are always small and
not-so-small features that would never have been built that way had the person
designing or building the house been intending to occupy it. Or had they moved
in, said problems would be remedied in short order.

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dboreham
Very interesting. I live in a place where we have significant issues with ice
build up on roof surfaces, gutters, etc. One way to deal with this is to
electrically heat the roof and gutters. This of course is expensive (very!).
So I had the ideal that one could use the available solar energy (it is
reasonably sunny in winter here) to melt the ice. My idea is not to use PV
panels and restive electrical heating but to directly transfer the solar
energy as heat to the ice. This would be done with some sort of heating panel,
coupled to the metalic gutters with a heat pipe. Sometime I need to do some
analysis to see if it is a viable idea. How to ensure snow does not cover the
panel/solar heat collector is also a potential problem.

~~~
WalterBright
> How to ensure snow does not cover the panel/solar heat collector is also a
> potential problem.

Mount the panels vertically.

~~~
pinko
Not always sufficient!

[http://c8.alamy.com/comp/D0DG83/stop-sign-covered-in-snow-
du...](http://c8.alamy.com/comp/D0DG83/stop-sign-covered-in-snow-during-a-
blizzard-D0DG83.jpg)

~~~
redtexture
Not an insulated capture point. Backside of the example metal sign always
cooled on backside by low temperature air.

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imaginenore
I actually built a similar system as an experiment, basically a 1 x 2 x ¼
meters (multi-layered) cardboard box painted all black inside and covered with
a sheet of transparent plastic on one of the larger sides. It was really
cheap, around $10-15 in materials. Then I added two holes (in and out), and
put some cheap flexible air duct hoses with some old CPU fan, which was
another $8. On a sunny day it heats up the air incredibly well, where it
actually could be beneficial during the winter season.

Unfortunately there are big problems that I encountered that I couldn't solve
cheaply.

1) Mounted on the roof, it has to be sturdy enough to resist heavy rains and
strong winds. We get winter windstorms, and one winter it got up to 55 knots
with 70 knot gusts. I have no idea how to cheaply mount this box on the roof
so it doesn't fly off and kill someone.

2) Intake and exhaust hoses would have to go either through the walls or
through the windows. And since I don't own the house, my only real option
would be to cut circular holes in the windows, and then replace the glass when
we move out. Again, not cheap.

3) For the winter months I would have to also insulate these hoses, or they
would lose most of the heat on the way to the house.

EDIT:

I also think if you don't care about what your house looks like, you can
either paint it black or wrap it in black plastic.

~~~
rzzzt
Some people build these with painted beer can columns on the inside serving as
air ducts, see this video for an example:
[https://youtu.be/nuxanLdtwZQ](https://youtu.be/nuxanLdtwZQ)

They also tend to install it on the side wall; it doesn't get that much
sunshine in the summer, but it becomes more efficient in the winter when the
Sun stays at lower angles. External circulation of air is still required and
is usually done by using an electric fan.

~~~
imaginenore
Yeah, I'm fully aware of that design. I've seen tests of it against a much
simple design with the sheet of fabric in the middle, and there's basically no
difference. Cutting so many cans' tops and bottoms is actually not an easy
task, I had tried.

~~~
redtexture
A couple of pieces of plywood, for each window, and some foam strips for air-
flow sealing would do. This is not a big effort, just more than your
(exceedingly short-lived) cardboard design contemplates.

The gain in creature-comfort in the apartment, might be more than the money
saved in avoided heating, as a renter of the apartment.

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samatman
For a next-level extension of this idea, check out this paper on solar
closets:

[http://www.ece.villanova.edu/~nick/solar/solar.html](http://www.ece.villanova.edu/~nick/solar/solar.html)

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devenson
If he just made large windows out of the same double walled polycarbonate
panels, wouldn't they collect just as much heat from the sun during the day?
The problem with windows however is they don't insulate as well. Perhaps just
doubling up or tripling their thickness would achieve the same result in the
end, and be much simpler. What am I failing to understand?

~~~
nkurz
_What am I failing to understand?_

You might be missing that maximizing heat collection while the sun is shining
is not the goal, that too hot in the day can be just as bad as too cold at
night, that each layer of "clear" polycarbonate (ie, 2 for twinwall) blocks
about 10% of the light, and that gaping curtainless windows are not always a
desirable architectural feature.

How many buildings have you been in that have expansive south facing windows?
How many of them have been comfortable day-and-night year-round in a harsh
climate without mechanical heating and cooling? Very few buildings achieve
this, and I'd guess that none of them have large windows.

The Introduction to to the article is a good "introduction" to the issues. The
rest of the article explains the introduction. If you are interested in the
issues, it's a good article, worth reading in depth. But as the author says in
the preface, "I’d suggest reading this when you’re in a “learn” mode – because
if you’re in “skim” mode, you’ll just be wasting your time."

~~~
lucio
How about Double Glazed Windows and shades?

~~~
nkurz
It depends on your goals. One saying is that "a good window is still a poor
wall". A quality double glazed window still has about 10x the heatloss of a
well built wall. Here's a summary with a link to more:
[http://www.energyvanguard.com/blog-building-science-HERS-
BPI...](http://www.energyvanguard.com/blog-building-science-HERS-
BPI/bid/55519/A-Good-Window-Is-Still-a-Poor-Wall)

Shades can help with privacy, but what if you want the privacy at the same
time you want to be capturing heat? And if requires active control --- well,
that's by definition not passive. Interestingly, the new movement in high
efficiency houses is frequently for _low_ solar gain windows: well insulated
windows with special coatings to admit less heat while still admitting light.

From another standpoint, gigantic expanses of windows are rarely the best way
to build a pleasant room. As well as being a rare crossover between Computer
Science and Building Architecture, Christopher Alexander's "A Pattern
Language" has lots to say on this. Some excerpts here:
[http://kk.org/cooltools/a-pattern-
language/](http://kk.org/cooltools/a-pattern-language/)

Which is to say that opaque heat-gathering walls serve a purpose that is
separate than that served by windows. Both have their place, and they don't
tend to replace each other directly.

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dttocs
See also [http://www.builditsolar.com](http://www.builditsolar.com) for more
recent improvements and ideas for simple passive solar.

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dorfsmay
I knew about vacuum tube, but they are expensive, require a pump and something
to convert the heat back from liquid to air. This on the other hand has zero
moving part and requires no maintenance. Amazing!

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tonyarkles
That's pretty amazing! Clearly a lot of thought and effort went into getting
the design nailed down.

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intrasight
Curious if anyone sells such panels

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freerobby
Mostly smaller outfits but you can find them. See e.g.
[http://sunmatesolarpanels.com/content/view/2/31/](http://sunmatesolarpanels.com/content/view/2/31/)

~~~
intrasight
Thanks

