DIY solar water heating

Colombiano

New Member
Good morning all, Having owned factory made solar panels on 3 houses I am contemplating making my own and would appreciate some feedback on my ideas. I am in the process of designing and building a new modernistic house and swimming pool, I have plenty of land but do not want to see ugly solar panels or water storage tanks. My idea is to incorporate the solar water heating into the roof and use a circulating pump to move the hot water to the tanks.

Please bear in mind that many "normal" things are not readily available here, I'm near to the equator but 6500 feet above sea level, very similar temperatures and sun all year round, no chance of any frost unless there is an apocalypse. I never need heating or aircon in the house. I have plenty of space so am thinking of black alkathene piping rather than very expensive copper tubing, less efficient but much simpler to install, I would need more glass to encase it. Will the alkathene piping stand possible high water temperatures?

The tanks would be lower than the piping so I'm thinking something like a central heating pump and then a pressurising pump on the house supply. The garage roof could supply the house hot water needs, bathrooms and kitchen are very near. The house roof could have the same system but on a larger scale to heat the pool using the pool pump to circulate the water.

Your thoughts and comments would be much appreciated
 

Jackfre

Solar Enthusiast
One of my best system builds for pool heating was installing poly tubing in the concrete skirting around the pool. It cools the concrete while heating the pool and being close by requires little pumping horsepower to supply the water. As to the domestic, you do not say how much water you are trying to heat and store. It will matter to your system design. I have only used factory built dhw collectors so cannot speak to materials that would be suitable. Having used the factory built in the past I would think that your best option. Keep in mind that your diy project is going to be on the roof and if things go sideways you have to do your work up there.
 

Colombiano

New Member
One of my best system builds for pool heating was installing poly tubing in the concrete skirting around the pool. It cools the concrete while heating the pool and being close by requires little pumping horsepower to supply the water. As to the domestic, you do not say how much water you are trying to heat and store. It will matter to your system design. I have only used factory built dhw collectors so cannot speak to materials that would be suitable. Having used the factory built in the past I would think that your best option. Keep in mind that your diy project is going to be on the roof and if things go sideways you have to do your work up there.
Thank you, The piping in the concrete seems a novel idea, my pool will be long and narrow proposed 12 metres by 3 or 3.5 and 1.2 deep .... about 12.000 gallons I need to find out how much piping I could fit into the surrounds. Can you tell me your figures please?
 

Colombiano

New Member
Re the hot water heating, manufacturers panel are ugly eyesores. I want to integrate mine into the roof so that all I see is a glass panel with a stainless steel tank insulated and hidden. There will be two of us living there, the tank will be about 320 litres or 90 gallons. Very rare not to have sunny days. I would prefer to have a long narrow collector. I have a space in mind of 1 metre by 4 metres.

The garage will be single story, no problem for working on it thx
 
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nosys70

Solar Addict
there are several type of panels. The usual ones for water are the vacuum tubes , very efficient (you get get hot water even if the tubes are under snow).
But yes they are thick and ugly and most of them have some kind of tank build on it (while it is not mandatory)
another type , less efficient , is the flat panel, that looks almost like a photovoltaic panel. You DIY easily, it is just a metallic plate , painted black under a glass to keep heat.
since the tickness can be minimal, the aesthetic is not too ugly, but i think you can buy good looking panels for less that you will invest in maeterial and tooling.
 

Colombiano

New Member
Thank you, solar panels are not cheap here in Colombia but labour is, especially mine lol. I have seen some chinese imports but am wary as to the quality. I am willing to sacrifice some efficiency for aesthetics.
 

nosys70

Solar Addict
in that case, i do not think labour is the main parameter.
building a solar panel require copper tube , glass, aluminium etc.. that are all expensive material, especially if you need a lot.
labour cost would be then marginal.
some people even heat water by using black plastic pipe, that cost almost nothing and can be found in big diameter (like 1 inch)
industrial solar panel usually use cheaper metal, or embossed plate replacing tubes and apply industrial processes (like plating) to obtain
cheap and better optimized components.
For example you would use regular copper tube or plate that is usually thicker than needed, while industrial panel use the thinnest tube possible.

this requires huge press , machines and mold usually out of reach for DIY.

for aesthetic, an example give above would be to put a plastic tube into the ground, cover it with concrete and have everything invisible..
if your house is not build yet , that would be easy to include and very cheap to realize, added to the fact that the energy stored into the floor last a lot longer than the available sun, so you can get hot water long after the sun is gone.
 
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Colombiano

New Member
As I said in my first post .... I have plenty of space so am thinking of black alkathene piping rather than very expensive copper tubing, less efficient but much simpler to install, I would need more glass to encase it. Will the alkathene piping stand possible high water temperatures?
 

nosys70

Solar Addict
if the pipe is enclosed in concrete i would not worry.
if the pipe is exposed to the sun, you would worry more about UV resistance than temperature, because alkathene is HDPE polyethylen, and polyethylen as bad resistance to UV
if the water is running constantly into the pipe you should not go very hot, usually HDPE tubes are rated up to 60 deg. C
but the problem is such installation is supposed to run for years. If you plan to change pipes every 3 years, then it is not a problem.
 
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Fred S

Solar Addict
Have you considered splitting your system and using PV panels to electrically heat the water for the house? (Perhaps still use piped panels to supply the pool, which would prevent the need for the water system's lines being inside your house.) For the amount of indoor hot water you'd need and your abundant sunshine, I'd estimate you'd only need 2 kw of panels (e.g. six 330 watt panels). There are controllers available that do this, with no charge controller or inverter needed. I would use several controllers for redundancy - e.g. one controller for each heating element in an electric water heater.
 

Jackfre

Solar Enthusiast
We put 1" pvc in the slab with parallel flow, reverse return from a 1 1/2" header. There was no engineering. It just seems like a good idea and it worked. I did some systems back in the 70's when I was in the business that were "built-in" to the roof as you describe. First you have to make sure your sub-roof is secure and water tight. Do not overlook this detail;) Given that it is a glazed system you will be talking high temps. I do not know what today is the best diy material to use. Copper was the go to and I believe it still is. When all is said and done, even with expensive material and cheap labor I think you will find that the best option remains a factory built collector. But, I will be interested to hear how it goes for you.
 

Colombiano

New Member
Yes I have looked at heat pumps and had a quote, almost as much as building the pool! I assume that most posters are USA or UK. There is a vast difference in price here, everything that has to be imported carries a huge "luxury" tax.
 

Colombiano

New Member
We put 1" pvc in the slab with parallel flow, reverse return from a 1 1/2" header. There was no engineering. It just seems like a good idea and it worked. I did some systems back in the 70's when I was in the business that were "built-in" to the roof as you describe. First you have to make sure your sub-roof is secure and water tight. Do not overlook this detail;) Given that it is a glazed system you will be talking high temps. I do not know what today is the best diy material to use. Copper was the go to and I believe it still is. When all is said and done, even with expensive material and cheap labor I think you will find that the best option remains a factory built collector. But, I will be interested to hear how it goes for you.

Thanks, sub roof is no problem the planned site for the collectors covers a walkway.
 
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