Steel Roof and Solar Hot Water

There have been a few solar hot water threads, varying from simple coils of black plastic tube to my 'homebrew' system, which is a good cheap starting point.
I'd sy it is probably extra trouble to try to incorporate it into the roof. I'd go for a simplified version of what I've already done.
Del

I did that under a tile roof. You need to create the space for it. (maybe use a router to create a "ditch")

I used CPVC piping. Works well when the sun hits the roof and the wind doesn't cool down the metal too much (in my case the tiles).

Make sure you arrange the layout well, that you can drain the pipe eventually. Zigzag slope from top to bottom.

You can fill it up with water and glycol to avoid freezing up.

The collector (tank) must have a jacket or heat exchanger and if the tank can be put higher than the outlet, you don't need a circulation pump in this circuit. Thermal Siphon principle.

Of course, under glass window, you will have more efficiency, since the wind doesn't affect the temperature, radiated to the piping.

I have both systems and if I have hot water under glass for 300 days, under the tiles only 240 days. But Lora treats us well.

I just found this link: http://zomeworks.com/files/double-play/TimMerrigan/RISA_8Nov02.pdf

in which the Department of Energy compares states that "Glazed collectors are ~10-15 times more efficient (per unit area) than metal roof RISAs (Roof Integrated Solar Absorbers).

Interesting. . . . I wonder how accurate that is?

I recently saw a solar collector which runs "Pex" -type pipe under the ridge-cap in a loop coil. Invisible and easy to maintain if need-be.

http://cr4.globalspec.com/blogentry/10724#

Wow! I like that idea for the ridge vent. When I bought my current house in Maine, there was a wood fired boiler connected to the DHW system. I could not get them to leave/sell the wood fired boiler as it had been "loaned" to the previous owner. So the system is sitting there using just the oil fired system for DHW at the moment, but still has all the connections to the storage tank....sooo all I need is the PEX and a pump and some plumbing! Hope I can get it done next summer. Thanks for the pointer!

I was at the local big box the other day pondering usability of a 250 ft roll of 1/2" black drip line, which cost all of $40, the trick would be figuring out how use the least amount of connectors & tie downs & keep it all running downhill....

You're much better off with glazed panel or encapsulated glass tube (the best there is, which I'm currently fabricating) solar thermal collectors independent of a new metal roof system due to the better thermal transmittance factors.

Be sure that any mechanical attachments and perforations (for piping, etc) through the metal standing seam roof doesn't invalidate your roof warranty!

Check out the www site for Mother Earth News for starters......there are many more not-for-profit websites on the Net....just do a Google search, and be sure to check the old blogs here in the forum!

Good luck building your system.

Every time I go to Mother Earth News I get agitated and irritated at the common line of thought.

There are some good things I am sure but trying to get through the junk is too much!

The architectural beauty of a home is often compromised when solar energy collectors are installed. Optimizing efficiency at the cost of compromising the look of a home is not acceptable to most home owners.

Getting some energy out of a roof by using a ridge collector or Sam's metal roof collectors have great appeal because they are designs which do not compromise a structures style. Another advantage of these designs is that they would intrinsically survive snow and ice conditions.

You made a good point Dell, Most of the so called technical metal roofs are forbidden in many European countries. If you are lucky they are approved for a horse stable. Unless they are sandwiched, they also compromise the roof structure in terms of condensation dew place in the structure. Plus: Solar on the roof means brains in the head, although this saying probably needs to be worked on. That is why I have some systems too. Lol. GA.

Solar on the roof means brains in the head

With present solar system costs?

With bankrupt governments plus neighbors helping to pay for them?

İf someone wants them fine - but why should tax dollars go toward it plus everyone else getting screwed with a higher electric bill to help pay (where the utility offers incentives or a FIT).

The original Robin Hood plan - in reverse!

I'm with Dell the Cat on this one. I have 36 solar PV panels on my southern roof and they look great! Plus they make tons of "juice" every day and turn back my electric meter making me money from the local utility company!!! hehehehehe!!!!!!!!!

The 52 solar thermal encapsulated tube collectors which I'm putting together will be mounted the south roof of my future 2-story steel toolshed (that I'm also fabricating).....I don't consider them an eyesore, & luckily my next door neighbors didn't voiced any concerns in the Village ZBA meeting held recently.

Del & Capt Moosie,

It all depends on the architectural style of the home. If the home is of a modern style, solar collectors can be incorporated easily to improve the styling. If it is an older style home in an older neighborhood. It becomes more challenging to make the panels blend in.

Reality is that some like the look of technology and others do not. For example, some like to display their big flat panel televisions while others spend a great deal of money and effort in trying to hide them. These big beautiful televisions are built into walls which have pictures which are put in front of them when they are not on, or they are put onto mounts which are motorized and fold into cabinets which match a designer style of the room. I've even seen televisions placed behind two way mirrors so that they are not seen when switched off.

I live in a 1911 Craftsman style home with historical significance. Putting solar collectors onto the roof would not be met with the approval of the local historical societies. To improve energy efficiency of the house, I removed all of the wood shake siding, upgraded the plumbing and electrical systems, then installed insulation before double wrapping the house with fiber reinforced roofing paper and then reinstalling the refurbished shake to restore the original look. For the attic, perimeter vents 1" tall were installed between each pair of rafter tails. This gap cannot be seen from standing on the ground looking up at the second story. Inside the attic, IR reflective insulation installed on the bottom edges of the rafters form a cavity or duct for removing summer heat. Vents along the ridge let the heat out.

It has been my experience that the creative intent, or style almost always takes precedence. For example, many new car buyers put styling as the highest priority. For me, my highest priorities are function and cost or ownership. But I am an engineer and my priorities are not in the majority.

It is my belief that energy saving technologies would get wider acceptance sooner if the buyers did not have to compromise styling. If more engineers would meet consumers part way by compromising efficiency for styling, the number of installed systems could increase and the energy technology industry would grow quicker.

My home has light fixtures with decorative bulbs in them. Replacing exposed clear glass or flame shaped bulbs with an energy efficient compact fluorescent lamps is not acceptable to my wife. She is right, styling trumps the energy savings. If energy efficiency was the priority we would replace all the the historical incandescent fixtures with fluorescent fixtures.

One more thing about metal roofs. My brother lives where snow is seasonal (about 2 to 3 months) and metal roofs are preferred because they can support the weight of the snow and his snow removal crew when they walk on the roofs to shovel off the snow after a heavy storm for his clients. Although solar collectors collect more energy when mounted in direct contact with the sun, they are not sturdy enough to withstand the winter seasons. Increasing the strength by increasing glass thickness would increase the weight beyond what most roofs could support. Therefore, solar collectors are not installed. Under these conditions, compromising efficiency by collecting heat through a metal roof would be the only viable solar solutions that customers would buy in his region.

Hey dvmdsc and russ,
Life sounds real tough for you guys.
Maybe we should organise a collection or aid package to help you guys out.
Come to think of it, I'd love to personally deliver a few beers if you need 'em.
Del

The second suggestion sounds great!

Didn't realize cats liked beer though?

Just found this site, I am not affiliated in anyway, I just like the photos particularly the standing seam roof with pex (aethestics):

http://www.dawnsolar.com/gallery.html

Does look cool, but it must be a pig to bleed the air out of all that pipe.
Del

Right - that is probably not a real roof but a make believe thing.

try ceramic based insulating paper (like ceramic paper , thin cera wool) to insulate your gerrage roof, that should be fitted under your roof..