Green Dream: A Solar-Powered Water Boiler

Additional : I'm using a tank loading system to "warm up" the water in both the domestic and the radiant tanks. If the solar panels are warm enough I'll run the glycol thru the heat exchangers in each tank based on need. If for example the domestic water tank is at full temp the full solar panel array will be dedicated to the radiant floor load in the winter. When I can't produce enough from the solar panel for domestic and radiant demands I'll use my geothermal system to "charge" up the water in both tanks- via a second heat exchanger located in each tank...

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Popular Science Magazine

I built a smaller one of these for research purposes at school. We used a propane torch on the underside to apply some solder to the small gaps left between the metal plate on the bottom and the pipe, to aid in conduction. It wasn't a good bond between the two, so it won't hold the pipe in, but it is better than air.

The text says 375 feet of copper tubing per collector. It would be nice if the layout was shown or described.

Why is the schematic for the tanks, pump, valves, controls, etc. not given? This is the hard part for me.

I noticed you used black paint in the project. A competitive magazine published over 20 years ago found that a dark (leaf) green color efficiently absorbed more heat than black. A paint used for automotive exhaust manifolds would be good if you could locate a suitable color. In that same article tubing was also silver-soldered to sheets of copper flashing. I believe you could use any absorbent metal, creating a "hat-shaped" section, over the copper tubing using a thin coat of (electronic) heat sink compound to improve the thermal bond between adjacent metal surfaces.

In my (Southern US) climate all solder joints may need to be silver-soldered to prevent future leaks, and it might help to use 6 inches of fiberglass insulation underneath the absorbent surfaces. The effects of solar heat may well melt some of the more critical solder joints if you use regular plumbing solder. Silver solder is usually available from suppliers of heating and air-conditioning parts.

The specification of 375 feet per pannel 3 x 10 does not make sense (75 feet x 5 pannels) look more probable. Can you please confirm this and also what size piping is used 1/2" or 3/4". Thanks

Very superficial article.
How much is the estimated cost?
How many joules of heat do you expect to capture?

You do a disservice to those who are interested in making real changes with a poorly researched "comic book" article such as this. Don't talk down to us. We are big boys - lets have some science in the article.

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Nature is in the intensive care ward, and we are ripping out the IVs.

Could someone post a link that will provide more detail of the components of the collector, how they are assembled, more detail on the plumbing layout, etc. Thanks

It seems like a bad idea to use so many soldered joints of copper pipe, as it increases the chances of leaks later on. Will the solder hold up to longterm extreme heat conditions that may occur on top of the roof in the summertime? Does all the air have to be bled out of the glycol circulation system like it does in a car's pressurized cooling system? The system sounds like it could be riddled with unforseen problems so it might be a good idea to design it to be highly serviceable.

When reading through the other 'Green Dream' posts, I can't help but notice that this one, that clearly pertains to the topic, has been conveniently left out of the posts. John Carnett's name also does not link to this article. PopSci, please tell me that you aren't trying to hide an article from us because people are being critical of the article's merits. The benefit of user comments is obvious, but what is the point of letting users comment if you are going to squelch their input by hiding articles like this? Now, can we please put this article where it belongs on the site.
Thanks,
Matt

Now this is a good system, though, I do favor the concept of underground heating. I am informed that you can recycle the water and given it is underground there is little temp variation and water loss through vaporization is minimal.

Regards,
Steve
www.designerradiatorstore.co.uk