I’m interested in setting up a solar hot water system with the vacuum tube technology. However, I’d like to do this away from the house itself. My question is, what material is the pipe made of that transports the water to and from the collector? If it’s buried under ground does that suffice for insulation? Also, is there a typical pipe diameter for a residence? I’m trying to stub out piping and conduit connections for various systems prior to pouring rat proofing in the interior of a grade beam foundation. If anyone has experience in this area, or knows where to find out about it, I’d appreciate the input.
Tom
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Not to rain on your parade but if you go to Green Building Advisors web site they would pretty much universally recommend against solar hot water. They would recommend the money be spent instead on Solar electric instead which then can be used to heat the water via electric or heat pump water heater. I would go check there to investigate the logic and economic cases they lay out against solar hot water.
Say what? Solar hot water is one of the few green technologys that actually make sense in some climates. Down here in south Florida most houses had homemade solr water heaters that worked just fine. I still see them on house that were built in the 30's and 40's.
I agree.Low tech like simply heating water beats high tech like solar PV every time.
That is particularly true when you factor in cost.
"I agree.Low tech like simply
"I agree.Low tech like simply heating water beats high tech like solar PV every time."
Care to prove that statement? Where is your financial analysis?
Again, you didn't even bother to go to the resource I provided. Go there and refute their analysis. Telling the OP to go Solar Thermal without any facts, figures or analysis is useless. Back up your post and prove GBA analysis wrong.
http://www.greenbuildingadvisor.com/blogs/dept/musings/solar-thermal-really-really-dead
If you live in south Texas where the black fiberglass tank on the roof counts as a water heater then it's incredibly cheap to install and run. But I can attest that showering in water heated by such a unit on a cool day in January is less than enjoyable.
First of all, read and comprehend what the man wrote. He isn't talking about some DIY system. Hes is talking about a vacuum tube system which is a commercially built system. Secondly, I told you where my information came from but you apparently couldn't take the effort to go there and review THEIR reasoning (not mine) for saying it is cheaper to heat hot water with Solar Electric than with solar thermal. I'm sure they would love to hear your argument in opposition to their position but I would come prepared with detailed cost and thermal output numbers or they will bury you before you even get you first post typed.
Simple Is Best
Solar electric to heat water? Really? Heck, let's put a Mr. Fusion in the DeLorean while we're at it.
Solar hot water for residential use is so proven, it was routine for Israeli dwellings in the 80's. Every house had the water tank mounted above the roof, with collector panel attached. Typical panel size appeared to be about 3'x6'. This was, of course, in addition to the elements within the tank itself.
Before then, it was common in the 70's for Californian homeowners to run their pool water through a coil or two of 1/2" black irrigation tubing to heat the water. This simple expedient really cut power bills and extended the swim season.
I've seen factory-recommended CPVC fail on the first sunny day after installation. I'd make a solar array using multiple small collectors, and connect them with copper tubing. I would keep the tubing above ground, for accessibility- repairs WILL be needed at some point. Insulate the pipes, and have an expansion tank in the system. It's best to have several small expansion tanks, one for each separate section.
"Black pipe" isn't nearly enough. It needs to be enclosed, and covered with tempered glass. Lexan will quickly yellow and lose strength in the sun, and Plexiglass will soon scratch.
A lot simply depends on where you live. If freeze protection is not an issue you can use a very low tech solution. I also point out to the "high tech is always best" guy that a modest water heater is going to eat 10kwh of power a day and a solar PV array that will put put that kind of power will cost you $25,000-30,000 based on the proposals I have on my fridge. That is not powering anything else or back feeding the grid. it is just heating water.
There may be some "welfare for the rich" out there that allows you to get the tax payers to fund some of your project but it is still a cost.
One hurricane or hail storm, and you are starting over.
I don't know if solar panels
I don't know if solar panels and heating tubes could be combined, but that seems ideal to me for solar applications. I don't know how high heat affects solar panel output, but if heat isn't a problem, you would basically have a solar water heater with PV power available to run the pumps (and more).
PV efficiency goes down as the panel heats up. Water heating is used in some systems to cool the panels, and increase the PV output. I don't understand why they are not use more often.
Quick Google check gives:
http://www.solimpeks.com/pv-t-hybrid-collectors/
http://dualsun.com/product/2-in-1-solar/
Those are pretty neat.
Here's a picture of my solar hot water heater. I know it doesn't look like solar hot water, but it is. It's a Rheem hybrid water heater with refrigerant and a blower fan. It takes the heat out of the air, and heats the water. We installed this in the front of our house, with an insulated pony wall, so that it would be next to our passive solar windows, where it is often 80-90 deg F.
It's a poor man's solar hot water, but almost equally as effective.