Posted by daestrom on September 22, 2006, 8:54 pm
Any information on how they work in really cold climates? They look really
sharp and well done.
In one photo, it looks like you have foam-board half-circles covering the
one end of the tubes. Is that to balance the flow through tubes, or just a
Folks in 'snow country' have reported good results of mounting just
vertically on the south wall. What's lost in not facing the sun directly is
made up for by snow-reflected sunlight. What's your experience been with
This is exactly the sort of panel I've been thinking of adding to my home.
Second story has a south-facing wall that is above the neighbor's
single-story house. Lots of reflection from his snow-covered roof. Oak
trees shade it in the summer, but the leaves drop off in the winter. I'm
thinking a panel such as this, with two holes in the upstairs
bedroom/hallway for ducting could be a real boost to heating. We get down
to 0F (-18C) quite regularly which is why I wonder about the temp rise in
really cold climates.
Posted by schooner on September 22, 2006, 9:21 pm
Yes the half circle inserts are to balance the airflow. Wayne balances each
one before the glazing goes on as the inlet and outlet locations impact how
the air circulates, balancing helps to even the flow through each duct so
there are no dead tubes.
We are in a snow climate here in Nova Scotia but typically not long periods
of extreme cold, mostly 0-15C on average during the day I'd guess with some
really cold days, but can't really offer much insight into whether the snow
reflection helps or not, I'd assume it does but it is hard to really
measure. My panel is mounted vertically on a south western wall and I get
good results although I am blocked for early and late parts of the day with
trees and the fact my house is in a low area. From testing there seems to
be an increase with a slight tilt angle, but that was in non snow season so
perhaps it would balance out.
With using inside air as the source and with the glazing and the fact the
air flows through the heated tubes and is never in direct contact with the
glazing I would guess it holds up fairly well even in colder temps but not
real measurements so far. I'll see if we can get some readings this winter
comparing the outlet temps to outside temp on clear days.
I've added some more pictures and info to the website:
Posted by Gary on September 22, 2006, 12:56 am
The collectors are really looking good.
Is the glazing material glass? or polycarbonate?
Wondering what are you using for the "extruded alum frame"?
It would be interesting to hear your experiences with the selective paint? I
have heard it can be difficult to work with?
I'm trying to sort out the advantages/disadvantages of using the alum tubes as
the absorber. One potential advantage I could see to the round tube absorbers
is that if the full circumference of the tubes heats up, then you have 3 times
the heat transfer area from the absorber to the air that a single flat plate
absorber would. Can you tell if the tubes heat up all the way around? A couple
of surface mount thermocouples would allow you to measure it -- let me know if
you want to borrow a couple.
I'd agree with Schooner that short ducts to the house should not be a problem.
You might want to think about how you are going to maintain them and keep them
from being damaged.
If you are going to go to the effort of building an external structure and
outside ducting, I would make the collector area as large as you can in order to
get the most out of the time and effort you put into the outside housings.
Could you get some extra use out of the project by integrating the collectors
with a garden shed, storage shed, sunspace, greenhouse, ...?
"Build It Yourself" Solar Projects
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Posted by schooner on September 22, 2006, 1:13 am
The glazing is actually Lexan, just single pane. The frame is slightly
curved on the front to give the Lexan a bowed out appearance. This was done
so the Lexan would keep its shape and not flutter in wind, and also will
always expand out when it heats up and not buckle and warp unevenly.
The extruded aluminum frame is from the big advertising signs you see and
minimalls, 7-11 and such to hold the lighted signage, we get it direct from
a sign company.
As far as I know the selective paint has been easy to work with so far,
spraying it on is fairly easy and it dries quickly from what my father has
said, you can also brush it on where needed although they suggest as thin a
layer as possible. It is the same selective paint used on many of the hot
water systems and we get it from a local company that builds solar hot water
Our thoughts on the aluminum tubes is the same as yours but no we haven't
tested it around the tube per se. On an early panel before we balanced the
airflow we had one tube that didn't get a lot of air and the foamboard
behind it showed signs of heat so I would say it is working as expected.
The other advantage of it is the rough surface that helps increase the
surface area and angles that it can collect sun on and also the fact it
gives a rough surface to the airflow to break up any laminar flow that could
happen on a smooth surface. We basically looked at the can idea and to us
it seemed less than ideal, too much effort and not the best airflow and lots
of areas for leakage. I'll see if we can get some temp readings somehow
from the back and sides, however is difficult to do in the assembled panels.
I'll try and get some more info posted on the website. Its been a work in
progress, so far I believe my father has built around 5 panels, each one
changing slightly, better materials, etc. The current aluminum frame
version is the latest and seems to be the best thus far in terms of weight,
performance, and overall looks.
Posted by darrylvan on September 22, 2006, 1:21 am
I'm thinking of integrating them with an outdoor garden shed. I'm not
sure how to lay it all out yet :)
I just built my house this year and hit onto this solar stuff after
construction. I wish i had been more conscious during the planning stage....