DIY Solar Heater

StephanienCarl

New member
May 20, 2016
4
Albany. NY
Hi there. My husband is in the process of making a DIY solar heater for our pool because the solar cover is not always enough. So my question is he wants to buy a submersible DC pump. Though he has not been able to find one that is okay in chlorinated water. Does anybody have any ideas? Because I'm really getting rather frustrated with the whole thing. I would greatly appreciate any recommendations or suggestions
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
13,633
Pleasanton, CA
In most cases, you can never build a DIY panel for less cost than a commercial panel and have the same performance.

But what does he plan to use the pump for? For most solar panels, the main pump is sufficient.

As for the chemical tolerance, you will need to check with the manufacture.
 

bioguy

Active member
Aug 5, 2018
41
Whitehouse Station, NJ
I built one last summer. It relies on pressure from the pool pump to push water to the top of my garage where I have about 1000 feet of 1/2 inch polyethylene drip tubing. I built two manifolds out of 1/2 inch tees to separate the input into 10 equal lengths of tubing and then collect them up for a return line to the pool. I drew a diagram below. It works even without the check valve and air bleed valve that I plan to add. I only run the pump during the day. There is also a valve on the line that goes up to the roof so that I can turn the flow off (for example, when changing filters or vacuuming). I don't like getting up on the roof or I'd take pictures of it. On a sunny day, the water returning from the roof can be +6F. Even on overcast days I get +2 F.

solar water heater.JPG
Total, the system cost about $150. About $100 for the black tubing and another 50 for the other fittings.
1 pvc tee that is 1.5 inch on the cross piece and 0.5 inch on the other piece.
1 garden hose bib
1 female hose connector for irrigation tubing
20 plastic tees (1/2 inch)

I get a flow rate of 2.83 gallons per minute from the heater. My pool is 12k gal, so it would take 70.7 hours to completely turn over the pool. If I'm running the pump 12 hours a day, that's 5.8 days to get a 2 to 6 degree rise. I enjoyed designing it and putting it together, so I'm not adding my labor costs. If you have the money, I have no doubt that a commercial version would work better.
 
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mas985

TFP Expert
LifeTime Supporter
May 3, 2007
13,633
Pleasanton, CA
@bioguy, sorry but I just don't want forum members to get the wrong idea about DIY panels.

1000' of 1/2" pipe is only 42 sq-ft of panel area. You can get twice the panel area at less than twice what you paid plus it will have much higher efficiency than your design.


Your design has inherent inefficiencies with the water flow which makes heat transfer much less efficient than what it could be. The distribution of water flow in each of the pipes is greatest at the edges of the panel and in the center, the flow rate is close to zero. This is the reason panel manufactures use larger headers and very small tubing. This technique evens out the flow between tubes. Here is a simulation I did for another member that shows the flow rate changes in the different pipes. Total flow rate and surface area is the same between the two scenarios.


1593896851685.png

1593896273703.png
 
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bioguy

Active member
Aug 5, 2018
41
Whitehouse Station, NJ
@mas985 No need to apologize. If I gave the impression that I thought DIY would be a better choice for raising water temperature per dollar spent, I apologize. I thought I made it clear that I thought a commercially available version would be more efficient. Thanks for running the math. Mine is definitely cheaper, but if the actual efficiency of the panels you linked matches your numbers, it's much better per dollar to go with the commercial version.

As I said, I had fun designing and building it. In retrospect, it probably would have been a better choice to use a design someone else had perfected.

I may need to do a side-by-side comparison if I can scrape together the money for commercial panels.