Passive solar heating panel plans
Morris Dovey
solar heating panels
http://www.iedu.com/DeSoto/solar.html
and sold them on-line until October 2010 to fund R&D of solar engines
http://www.iedu.com/DeSoto/Fluidyne/
Now that I've become physically unable to produce the panels myself, I'm
considering making a How-To available for others to build them.
http://www.iedu.com/DeSoto/SC_Madison/SC_Plan.html
Just putting together a good set of plans for someone else to work from
will take a fair amount of time and attention away from other efforts,
so I'd like to invite anyone who has a serious interest to let me know
using the "Feedback" button on the bottom of that page. If there isn't
enough interest I won't waste my time.
Warning: The project isn't as easy as it might seem at first glance -
and all dimensions are critical.
--
Morris Dovey
http://www.iedu.com/DeSoto/
PGP Key ID EBB1E70E
Jim Wilkins
> As most of the regulars in both newsgroups know, I developed passive
> solar heating panels
> Warning: The project isn't as easy as it might seem at first glance -
> and all dimensions are critical.
>
> --
> PGP Key ID EBB1E70E
My interest waned when the local plastic panel supplier quoted about
$3 per square foot. I have some of the much cheaper HD/Lowe's panels
outside on roofs for long-term durability testing. So far the clear
PVC panels failed, Suntuf polycarbonate has held up pretty well to
heavy snow and falling branches but hazed over somewhat.
Instead of the galvanized panel screws that rust I used stainless with
washers punched from old inner tubes.
jsw
Bob F
I don't have an immediate location for such panels, but I would be very
interested in educating myself. If only my neighbors would remove those poplars.
Jim Rojas
I have seen a similar design that uses aluminum cans to create the air
flow. It is an interesting design.
Jim Rojas
Morris Dovey
> On Feb 8, 10:16 am, Morris Dovey <mrdo...@iedu.com> wrote:
>> As most of the regulars in both newsgroups know, I developed passive
>> solar heating panels
>> ...
>> Warning: The project isn't as easy as it might seem at first glance -
>> and all dimensions are critical.
>
> $3 per square foot. I have some of the much cheaper HD/Lowe's panels
> outside on roofs for long-term durability testing. So far the clear
> PVC panels failed, Suntuf polycarbonate has held up pretty well to
> heavy snow and falling branches but hazed over somewhat.
I used Polygal(tm) 6mm twinwall polycarbonate (sold as a roofing
product) and have had excellent results. I have a 30 year old scrap from
my first Minnesota project of similar 1/4" GE material that still looks
brand new. I think you'd have to look pretty hard to improve much on
that $3/ft^2.
> Instead of the galvanized panel screws that rust I used stainless with
> washers punched from old inner tubes.
I used stainless steel wherever I could (except on the trim, where I
used 1/8" aluminum). Even the pop rivets used to secure my absorber were
stainless. By the end of production I was even using stainless steel
"paint" to protect from UV, moisture, and cellulose-eaters. :)
I've heard too many stories of panels being junked after only five or
ten years of service. We all like to keep costs down, but sometimes it
really does make sense to 'spend what it takes' to do a quality job.
--
Morris Dovey
Morris Dovey
> I don't have an immediate location for such panels, but I would be very
> interested in educating myself. If only my neighbors would remove those poplars.
It's an interesting area of study. It led me into subjects/topics that I
never dreamed would be applicable, much less hugely significant.
As you point out, not all sites are suitable for home heating - but you
can do a lot of learning in the shade and testing out your ideas in even
just a small patch of sunshine...
Morris Dovey
> I have seen a similar design that uses aluminum cans to create the air
> flow. It is an interesting design.
<grin> If you have, the similarity ended with the box. The bad news is
that an aluminum can collector _can't_ be efficient for space heating.
z
news:iirr16$m5d$1...@news.eternal-september.org:
>
> I don't have an immediate location for such panels, but I would be
> very interested in educating myself. If only my neighbors would remove
> those poplars.
I might be able to ship you a crate of beavers for a reasonable price.
Just sneak over and put peanut butter on the base of those trees and turn
em loose!
-Zachary in Oregon (the beaver state!)
Bob F
Problem with that is that my garage and house are well within range.
Jim Wilkins
> ...>
> I don't have an immediate location for such panels, but I would be very
Don't the leaves fall off at the start of heating season?
Bob F
Yes. So they only block 2/3 of the sun for several hours a day.
Morris Dovey
and http://iedu.com/DeSoto/SC_Madison/SC_Plan.html on February 8, 2011
and results were tallied on March 8, 2011.
207 visits to web page in February
+51 visits to web page in March
---
258 total visits to web page
-8 e-mails expressing interest ("yes" votes)
---
250 not interested enough to respond ("no" votes)
Effort required to produce a reasonable quality How-To: 1+ month.
One respondent indicated a willingness to pay up to US$50 maximum.
Conclusion: There's not enough interest to justify the time and effort
needed to produce a good How-To document.
My thanks to all who visited/responded.
--
Morris Dovey
DeSoto Solar
http://www.iedu.com/DeSoto/
Curbie
wrote:
>Conclusion: There's not enough interest to justify the time and effort
>needed to produce a good How-To document.
Morris,
I recall seeing your panels on BIS recently so it seems to me that
your audience is larger than just a.s.t or a.e.h and after reading
Yahoo.SolarHeat every day for a couple of years, it also seems to me
that the passive fans are growing in numbers.
I'm still an active fan due to a use of summer heated water, but it
seems a shame to hold back a viable passive design.
Curbie
Morris Dovey
> I'm still an active fan due to a use of summer heated water, but it
> seems a shame to hold back a viable passive design.
I agree. It's not a matter of holding back - it just doesn't make sense
to spend that much time producing a How-To for so few people while other
problems remain unsolved.
In the "unsolved problem" category, here's a time-lapse video of a
(non-electric) solar-powered tracker built by a clever Kiwi:
http://www.youtube.com/watch?v=V0r5LP_kKVA
The jitter is the result of wind and (a lot of) backlash in the drive
train, but the approach taken looks good.
sno
effort....
thank you much....have fun....sno
--
Correct Scientific Terminology:
Hypothesis - a guess as to why or how something occurs
Theory - a hypothesis that has been checked by enough experiments
to be generally assumed to be true.
Law - a hypothesis that has been checked by enough experiments
in enough different ways that it is assumed to be truer then a theory.
Note: nothing is proven in science, things are assumed to be true.
Curbie
If you or anyone read anything negative in my use of the term "hold
back" it was not my intension and I apologize.
I still like the single axis clockwork tracker used on the Scheffler
concentrator, but I don't really see from the video how that one
works.
Curbie
Morris Dovey
> Just wondering how much you calculate would make it worth your time and
> effort....
>
> thank you much....have fun....sno
At 3%, the idea had a lower approval rating (among folks with an
interest in solar heating) than George Bush's foreign policy.
What's to calculate?
Morris Dovey
> Morris,
>
> If you or anyone read anything negative in my use of the term "hold
> back" it was not my intension and I apologize.
I didn't, but was sensitive that some will consider that it's
unforgivably selfish of me to drop it and move on with other projects.
You have nothing to apologize for.
> I still like the single axis clockwork tracker used on the Scheffler
> concentrator, but I don't really see from the video how that one
> works.
It's a bit easier to see here:
http://www.youtube.com/watch?v=xHl-nuBpe5c
The obvious advantage in my pumping context is that the pump can (also)
keep the tracking reservoir filled.
Curbie
wrote:
>On 3/8/11 3:29 PM, Curbie wrote:
Curbie
>It's a bit easier to see here:
It is.
>The obvious advantage in my pumping context is that the pump can (also)
>keep the tracking reservoir filled.
At a cost, I wonder how much water it take to drive that tracker on a
daily basis???
Curbie
Morris Dovey
I don't know - Daniel just got his prototype working. It appears to be
cobbled together using bicycle parts and pop/beer cans - which should be
available in a lot of developing areas.
I'd be willing to bet dollars against doughnuts that it'll see a fair
amount of improvement. (I have a few [half-baked] ideas of my own) :)
Curbie
In order to compare the merit of two plans (active to passive or
passive to passive) it seems that someone would need both plans. The
thing I like about your passive collector is cost, size, and the
ability to retrofit them to an existing structure, a lot of passive
plans require the space and cost of mass thermal and large amounts of
costly thermal glass.
If you don't have time... you don't have time, just seems a shame to
abandon let hard earned knowledge.
Curbie
Morris Dovey
> In order to compare the merit of two plans (active to passive or
> passive to passive) it seems that someone would need both plans. The
> thing I like about your passive collector is cost, size, and the
> ability to retrofit them to an existing structure, a lot of passive
> plans require the space and cost of mass thermal and large amounts of
> costly thermal glass.
The original goal was to arrive at a commercial product that the
construction folks could treat like a standard window unit or pre-hung
door, and that could be installed in a conventional structure to reduce
heating costs.
The installable module approach turned out to be a good idea, and (to
even my surprise) an exploration of the physics led to a panel capable
of delivering 100% of the heat for an ordinary, conventional structure.
One of the things I learned was that an active panel _cannot_ outperform
a sufficiently well-designed passive panel. At first that seems
counter-intuitive - but it's true, because efficiency doesn't come from
a fan.
What seems difficult for most people to keep in mind is that it's all
about heating _air_ (or water or whatever) rather than any of the
panel's parts. To build a /really/ efficient panel, the design needs to
operate at the absolutely lowest temperature possible, and the
difference between the warmest panel parts and the collection media
lowered to an absolute minimum.
> If you don't have time... you don't have time, just seems a shame to
> abandon let hard earned knowledge.
The knowledge hasn't been abandoned. I've been shoveling everything I
have into a USB FLASH drive. In addition, there are panels scattered
across the US and Canada to backup the data.
Right now there are a billion and a half people experiencing severe
water crises. See:
http://hdr.undp.org/en/media/HDR06-complete.pdf
for details. I think I know how to solve that problem, but it's going to
take everything I've got and all the help I can beg to get the job done.
Curbie
>The original goal was to arrive at a commercial product that the
>construction folks could treat like a standard window unit or pre-hung
>door, and that could be installed in a conventional structure to reduce
>heating costs.
This is what I like about the design.
>The installable module approach turned out to be a good idea, and (to
>even my surprise) an exploration of the physics led to a panel capable
>of delivering 100% of the heat for an ordinary, conventional structure.
I'm a little twitchy here, replacing household heating load during
sunlight I can see, I don't see intrinsic heat storage, never less the
return on investment for that alone gives the design merit.
>One of the things I learned was that an active panel _cannot_ outperform
>a sufficiently well-designed passive panel. At first that seems
>counter-intuitive - but it's true, because efficiency doesn't come from
>a fan.
Heat storage is still something that needs to be considered when
compare active and passive systems.
Curbie
sno
> On 3/8/11 3:06 PM, sno wrote:
>
>> Just wondering how much you calculate would make it worth your time and
>> effort....
>>
>> thank you much....have fun....sno
>
> At 3%, the idea had a lower approval rating (among folks with an
> interest in solar heating) than George Bush's foreign policy.
>
> What's to calculate?
>
thinking again....<grin>....have fun....sno
Morris Dovey
>> The installable module approach turned out to be a good idea, and (to
>> even my surprise) an exploration of the physics led to a panel capable
>> of delivering 100% of the heat for an ordinary, conventional structure.
> I'm a little twitchy here, replacing household heating load during
> sunlight I can see, I don't see intrinsic heat storage, never less the
> return on investment for that alone gives the design merit.
I can't fault your twitchiness - the 100% solar heat wasn't even hoped
for when the first two new panels were installed. In fact, I made the
strongest case I could for three panels instead of two - and I was
caught completely by surprise when the two were enough to slightly
overheat the building through that first winter.
To relieve some of that twitchiness, start with the volume of air in the
heated space. Once you know the volume you can approximate its mass, and
from that you can calculate the amount of heat energy in that mass of
air at room temperature. Now calculate the mass of storage media needed
to store that much heat at the same temperature. Knowing that, you can
use the density of the storage medium to calculate the corresponding
storage volume.
Note that that volume of storage is what's needed to raise the
temperature of all the air in the structure to whatever you called room
temperature exactly once - from a /very/ chilly -273.15˚C!
If you DAGS on [alt.solar.thermal]+"Physics help please" you'll see how
I muddled my way (with some expert help) to grasping why things played
so unexpectedly well. Somewhere in the thread you'll find a short
program that I wrote to do the calculation - and I'd guess that you
wouldn't have any difficulty adapting that to a spreadsheet.
>> One of the things I learned was that an active panel _cannot_ outperform
>> a sufficiently well-designed passive panel. At first that seems
>> counter-intuitive - but it's true, because efficiency doesn't come from
>> a fan.
> Heat storage is still something that needs to be considered when
> compare active and passive systems.
Heat storage needs to be considered no matter what - but the thermal
mass required has nothing to do with whether the method of heat
acquisition is active or passive. :)