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Posts: 1,845
Reply with quote  #31 
Found this site looking for a flow rate per cubic foot water collector and thought it was interesting.  Wondering why I have not seen these types of evacuated tubes before. Wonder if you could make one with a polycarbonate panel so it would filter light through but still heat water or use downspouts and put air through them?http://www.presentationcenter.org/Environmental_Mission/Welcome_Center/Energy/solar_thermal.html

What is the best flow rate per square foot for a solar water panel?


Posts: 243
Reply with quote  #32 
Hi Dan,
I think that about 0.04 gpm per sqft of panel is a good point to try to hit.  

Within reason, the more flow, the more efficient the collector will be because the temperature rise drops as the flow increases, and a cooler collector means less heat loss out the glazing.  But, more flow also means a larger, more expensive, and more power hungry pump.

The tradeoff on efficiency vs flow rate is here: http://www.builditsolar.com/References/ColFlowRate.htm

Like the look of those vacuum tubes used as a shading structure.

I think the green tint is not good -- the greener the glass, the higher the iron content, and more iron content leads to less transparency.

You could test the glazing by doing a side by side test like this: http://www.builditsolar.com/Experimental/TreeShade/TreeShade.htm
Set up some glazing you have around (SunTuf would be perfect) in one collector and your found glazing in the other -- the glazing that heats the water bottle the most is the winner.  Would love to hear how that comes out if you do it.



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Reply with quote  #33 

   The tint caused by iron was what I was thinking but when I searched I found this, "Ordinary soda-lime glass appears colorless to the naked eye when it is thin, although iron(II) oxide (FeO) impurities of up to 0.1 wt%[47] produce a green tint, which can be viewed in thick pieces"  This glass was used in display cases so I figure it is tempered and it is very thick, 1/4 inch plus,  This may also account for the greenish tint and while it may be caused by iron it still may not be excessive.  That may also be an issue because it is thick so it has lots of mass unlike the suntuff it may hold the cold more than suntuff would have.  I do have some thin very clear lexan I could compare it to but I'll probably use it in the end anyway.
   I bought a DC pump today for experimenting, it says 200 gallons per hour so I'll have to see if I can slow it slow  to about 1/4 to a 1/3 of that.  I was hoping to power it with my small solar panel but a 7 watts it's probably too small.  Won't hurt to try though.
   I like those vacuum tubes also but since I can't build them I was thinking of two layers of twinwall with downspouts or water pipes in between them and the lower layer would be tinted or have a thicker layer of screen laying on it to collect light and allow heat builtup.  This would still allow some shading but some light through also.  Make a nice useful porch cover.


Posts: 8
Reply with quote  #34 
Dear Scott and others

Since my initial posts seem to have been taken well, I will describe my experience with solar since 1981.

I will begin with a profile. If you don't like what I say, just say so and I will go away.

I have been more or less what today is called a prepper since 1950. My parents lived through the depression and anyone who did never wasted anything.

In 1950 we were living in a rural house in Central Ontario. Our modern technology consisted of electric lights and a radio. As for running water, you ran to the river with a pail to get it. We had an ice box, and I can still remember trips to the icehouse beside a bridge over the railway tracks. We had a root cellar with enough food for the winter so we wouldn't starve, but, had we been forced to rely on it, the variety was not great. Of course, my mother bottled preserves.

In 1953, we moved into the big city (pop2500). My parents bought a house from an old retired doctor. He had retired in 1937 and continued to live there with his wife just as if it was still the 19th century. The day his wife died he left and never once returned. The place was fully furnished, (covered with drop cloths), there was even food in the pantry.

There were sidelights and transom lights on the doors (the latter is a window over the door). There was no running water, just chamber pots; no built in closets, just armoires. We had a summer kitchen. For those of you born to 21st century houses, cooking was done with wood or coal. Using it in the summer made the house too hot, so an outside kitchen was provided. There was a separate stairs to the maid's room. There was a formal parlour were you entertained guests. Even though it was an urban house, there was a barn in the rear, with a carriage house, a stable for horses, cows, pigs, chickens and a hay loft. There was was a well and a cistern for rain water.

I have since visited 19th century house reproductions in pioneer villages and they look just like that house did the first day. My parents modernized the house once town water was available, installed a refrigerator, an electric range and a TV (one channel). They converted the summer kitchen into two rooms for boarders. My parents had great luck with boarders. They got rid of two daughters that way. Of course, we still had preserves and a root cellar. And they never destroyed the character of the house

In 1961, when I was in high school, I undertook to study the Romans on my own. Most people think of the Romans as a failure; the truth is their empire lasted a thousand years. Roman roads, aqueducts and sewers were wonders of the ancient world, even though they were not recognized as such even then. They enabled Rome to become the first city of about a million.

The Romans did fine as long as they were a rural empire. Then they moved into cities [city] and became consumers instead of producers of the necessities of life. They became more dependent on political handouts, whined when the grain ships were late and spent the time that they used to use providing for themselves watching sport spectaculars.

Sound like anyplace you know?

I think you can understand how my upbringing and my research (you may have guessed I am a student of history) has made me a proponent  of the Muslim adage: "Trust in God, but tie your camel".

Ab (canadiannorthernhistorian)


Posts: 8
Reply with quote  #35 
I have already found the immediate information I was looking for.

So I will begin a detailed story of my experience with energy efficiency and passive solar, so others just might profit from my successes, and perhaps learn from my mistakes.

I include it here rather than general design since this site gets more hits and it is just a general discussion.

I don't know how many posts this will take. I will include plans and a photo or two if I can figure out how to post them.

My father was a stationary engineer, I had one brother who was a building superintendent, one who was a auto mechanic and one who was an aircraft mechanic. I was very much the youngest of the family, my father was 49 when I was born, my oldest brother was 22.

I went to university but it was for an education, not a job training. By the time I started university I was already a carpenter.

I worked a lot on concrete piers for highway bridges and it taught me a lot about concrete and form work.

I was also an architect but never had any papers. At that time, where I lived, I learned you didn't have to have papers if you didn't design/build over 3 stories. I never did and saved the expense of papers.

I designed and built my first house ( a play house) at age 12. I designed my first real building ( a bakeshop with an apartment over) at 16. My design was good enough (I would make changes now) but my experience in supervising a work crew left a lot to be desired. The 50 year old building is still in use.

I rebuilt my first "energy efficient" house in 1973 by adding insulation and a cistern. I also had a well "witched", to supplement the existing well, but it came up dry.

Ab (canadiannorthernhistorian)

Posts: 8
Reply with quote  #36 
We (I was married by then) stopped our planning and pipe dreams and made our first move to passive solar in 1980-81.

We were living in a town house in the "city" (24,000) and looked for a rural property. We looked for 15 acres but ended up buying 55 acres because it was just as cheap. The property had 10 acres cleared, with 15 acres of softwood with a pond and small brook, and 30 acres of hardwood (mostly maple).

We were lucky to sell our townhouse, and rented another in the same complex for the construction period. Moving across a driveway was the hardest move I ever made.

We were lucky to be able to invest the money and get a vendor take back at a lower rate.

Interest rates were high and nobody was buying/building. Our vendors were willing ( I was going to say happy, but that would be stretching it) to lower their price and take a mortgage at a reduced rate.

Also, when it came to buying materials we were able to get bargains because when suppliers found we wanted a house lot of materials they practically grovelled a our feet.

I think our planning was good, but also we had a lot of good blind luck. Our principal luck was being able to sell the OUR townhouse. That is what comes of good living. LOL

My wife called it the "boonies". I said anyplace that was 5 minutes off a four lane highway hardly qualified as remote.

The first issue was water. We knew of a couple that had built first and then drilled a well (they never got a good supply). It cost so much, they had to sell.

So water was first, even before a driveway.

My wife didn't believe in witching and my previous experience with it had been very bad (see previous post).

I went up and down the concession road and talked to everyone. Those who had drilled wells had to go deep and had a poor supply. The two who had dug wells had a better supply and better quality.

The property was in a "collection" basin and the problem was too much water (close to the surface). We could always have taken water from the pond/brook.

I talked to a hydrologist, he recommended what to look for and we hired a backhoe.

We hit water at 12 feet. I don't know how much water we had because we rented a big pump rated at 200 Imperial gallons a minute and we couldn't pump it dry. We turned the front of our property into a lake and we lowered the level, but no way could we pump it dry.

So we had water.

The next project was a driveway. Our stream divided into two and a seasonal stream ran in front of where we built. We measured the flow (this was done at the spring peak) and sized a culvert.

Only thing was it froze up in the winter, dammed the steam and flooded the driveway and front of the property. So we had another lake. We had to replace it with a much larger culvert.

I had the basement excavation done also in the spring at the highest water table. We went down 18 inches and hit water. I called it off right there.

So the house ended up 30 inches higher than planned. It meant changes to the design, and back filling, so the house, and also the septic bed, ended up on its own little hill. As a precaution, I added 1 foot to the height of the basement walls and put in 12 inches of crushed gravel below the basement floor. 

We had the only dry basement on the concession, even with our flooding problem. We had a sump pump, but never used it and loaned it more or less permanently to a neighbour.

I have an incoming email from another historian with questions so I will be back.

Ab (canadiannorthernhistorian)


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Posts: 1,845
Reply with quote  #37 
I found some glass on craig's list today, basically 14  4X6 sheets of 1/4 inch new tempered glass for 75.00 dollars.  I even have somebody willing to take 2 at 10.00 each and can probably get rid of a few more for similar prices.  Unfortunately the wife thinks I don't need any more glass, (or solar panels).  With 14 sheets I can build a greenhouse, make a sunroom/greenhouse for the back of the garage that will also supply heat, make a couple of water heater/collectors.  It also solves some of the issues I had with polycarbonate and plexiglass, see: 

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Posts: 2,240
Reply with quote  #38 
No Sweat, Dan, take it all !

I'll even take some myself

Wives have a habit of being right most of the time, not-wrong some of the time, and dead wrong on the odd occasion.

Tell your lady from me that THIS is one such occasion !


(1)  "Heat goes from hot to cold, there is no directional bias"
(2) It's wrote, "voilĂ " unless talking musical instruments...

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Posts: 1,845
Reply with quote  #39 
  I would but she's not talking to me because of our "free health care discussion" last night.  (and please, this is not the forum so let's not go down that road).  As you said, another time I am wrong according to her, only she did not use such nice words.

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Posts: 1,845
Reply with quote  #40 
Had a pretty good solar day even though it started bad and ended bad,  The picture is my garage heater.  It has two issues, It is undersized by a lot, and the fan was over sized for the heat it produces.  The fan even in full sun would constantly cycle on and off because it would cool down too much.  I replace the one big DC fan with two smaller DC computer case fans.  They still put out a good breeze, and probably spread the flow out better.  In any event they did the trick and it never shut down till it got pretty cloudy.  As you can see it's pretty cloudy now though it was worse.  This heater started out as a metal plate backpass, (air flows behind the plate), and two separate window panes but I found a bigger piece of glass so I made it a little bigger.  I later took it apart later and added vents at the top and bottom to get air through the front of the plate also, baffles behind the plate, and one layer of screen it front of the metal plate.  It's 3X6 feet with double glazed glass on front.  The wall is great in the winter for sun when there is some but the 2 foot overhang is already starting to cover up about 1/4 of the panel and by summer it will be completely shaded.  I should change it over to screen but have been thinking about making it 4 feet high and 12 or 16 feet long for better output.  If I went with my original long screen plan and used solar screen I think I could really heat up the garage. (like the drawing below) 
But I did have great sun for about 1 1/2 hours and all my panels were cooking and they actually put out a lot of heat during the mostly cloudy periods.  The garage went up at least ten, the pole barn went up 15 degrees, the shed went up 20 degrees, and the wife had windows open in the house..  Overall a nice 33 degree spring day.  Saw my first flies outside today, probably have mosquitoes next week but my vans still stuck in the snow.

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