Homemade Solar Array

[smid87]

Split by moderator from HERE as it was not really on topic. jblizzle

For less than one panel, you could build your own. I have 5 100' 1/2" black poly water pipe coils connected to two 1&1/2" headers and this was around $200 for the materials. My raised platform is within a few feet of the pool so I did not need to spend much on PVC pipe. I held my hand near the return yesterday afternoon and there was a considerable difference between the pool water temp and the return water temp!!! I know that is not scientific, but it sure felt good to know it was working well. I should mention that part of the cost of materials was some "clear" plastic that I used to cover the whole solar array so that I could pick up some extra heat from a solar oven effect. It gets to around 150 degrees inside!!! I put an oven thermometer in it and it actually starts reading at 150, but I can tell from the needle position that I am at or near 150 because the needle drops well below the point. Next will be to automate it!!!

 

[jblizzle]

Re: Repair suggestions for damaged Aquatherm solar panels

Those 5 runs of 100 foot are only about 20sqft of area. For that amount of money you could have bought 80 sqft of panels off eBay. It does not pay to make your own anymore ... except for a sense of accomplishment.

Solar heating is always most efficient when the temp rise is only a few degrees, so sounds like you are not moving enough water through your setup.

 

[smid87]

Re: Repair suggestions for damaged Aquatherm solar panels

Those 5 runs of 100 foot are only about 20sqft of area. For that amount of money you could have bought 80 sqft of panels off eBay. It does not pay to make your own anymore ... except for a sense of accomplishment.

Solar heating is always most efficient when the temp rise is only a few degrees, so sounds like you are not moving enough water through your setup.

I did the math on them and it is at least 62 sqft, but with the roundness of the tubes, it is likely more. The diameter is 4 feet so pie R squared is 12.56, but I have read many places that the actual square surface area is more like 25 sqft. If that is the case, then it would be around 125 sqft. Based on the heat output I would say it is more likely the 125 sqft.

Then you have to add the solar oven effect from the enclosure around it and there you have it. A solar array for little money and efficient enough. It raises the water temp 6-8 degrees on a sunny day. Outside temp is not much of an issue because of the oven effect. It usually gets at or over 150 degrees inside the array. The return water is noticeably warmer, but not significantly so. I did not do much math on the output so I get what I guessed I might. Real science at work :lol:

I should add that I painted the inside flat black and added a few rocks (painted them too :-D ) for heat retention when clouds pass. Not going to do much, but every little bit counts.

 

[jblizzle]

Re: Repair suggestions for damaged Aquatherm solar panels

I think you are a little arbitrary with rounding up your math there ... 5 * 100feet * 0.5 inches * 1ft/12in = 20.83 sqft ... That is the sqft of the tubes exposed directly to the sun ... even if the OD of the tube was 1" and not 1/2" that would be less than 42 sqft.

If your coils are not tightly wound, you can not say the exposed area is 4 feet diameter. And you certainly can not say you have 125 sqft of exposure when you only have 500 feet of 1/2" pipe.

Now the fact that you have enclosed your setup certainly makes it more efficient as you are getting some heating all around the tubes and not just getting heating directly from the sun exposure. You have also protected the array from cooling effects due to the wind so that helps as well.

I am glad it is working great, but hard to say if it is truly more efficient than 80 sqft of actual solar panels ... especially if you enclosed the panels like you did the coils.

Do you divert all the flow through the coils? Do you know the temperature delta you are getting between the incoming and outgoing water?
You may be able to add even more heat to the pool if you can increase the flow rate through the coils.

BTW, I am going to split this discussion as it has nothing to do with the thread.

 

[cramar]

gotta say that I pursued the DIY solution for some time but after enough research came to the conclusion that commercial panels are the way to go, both for cost and performance.
It's all about as much square footage as possible and then getting as much flow thru as possible, ironically the temperature coming out the end can be the least of concerns. I can turn my flow down and get some really hot water coming out, but I don't, I crank it up and get alot warm water into the pool instead of a little bit of hot.
With tens of thousands of gallons to heat, it's about volume, not necessarily temperature.

Once again TFP was right, just my 2 cents.

 

[smid87]

Re: Repair suggestions for damaged Aquatherm solar panels

Do you divert all the flow through the coils? Do you know the temperature delta you are getting between the incoming and outgoing water?
You may be able to add even more heat to the pool if you can increase the flow rate through the coils.

I do divert all the flow through the coils. I do not have a way to measure the temp in and out so no temp delta. Budget was a big issue and I have built one of these with one coil before and it would get warm. I did not know you could get panels for under $100 dollars or I might have chosen that route. I do have two dysfunctional leaking panels that I could probably cob back together. :-D

 

[jblizzle]

FYI, when I bought my current house there was a DIY solar on the roof ... 2500' of 1" black poly tubing laid all over the roof. It went up and over ridges and overlapped and was not well laid out. In fact water may not have even been going through all 8 of the circuits. I figure at best it could have been 200 sqft, but likely less due to overlapping. I was also always fighting with leaks (probably because the would never drain completely). Much happier with my 500 sqft of panels now.

The prices of these panels has come down a lot in the last few years ... as I said, if what you have is working that is awesome and likely it was something you enjoyed building.

 

[smid87]

FYI, when I bought my current house there was a DIY solar on the roof ... 2500' of 1" black poly tubing laid all over the roof. It went up and over ridges and overlapped and was not well laid out. In fact water may not have even been going through all 8 of the circuits. I figure at best it could have been 200 sqft, but likely less due to overlapping. I was also always fighting with leaks (probably because the would never drain completely). Much happier with my 500 sqft of panels now.

The prices of these panels has come down a lot in the last few years ... as I said, if what you have is working that is awesome and likely it was something you enjoyed building.

From what you are telling me it should not be doing what it is doing, but it is. I just drew from solar hot water panels which are laid out very similar to what I did (not coils though). I get 4-6 degrees of water rise every sunny day. Now that I put in a solar cover, I get an extra 1-2 degrees from that and major heat retention overnight. Yesterday was 78 for a high and the pool began at 70 degrees and rose to 76 by 4pm with the solar cover on and the solar heater on. Last night was 48 degrees and this morning we woke to the pool being 74 degrees (lost 2 degrees overnight!!) I am loving this and it was cheap. Any more and my girlfriend and I would just ditch the pool and find a pond to swim in. These things cost so much to operate so every penny we can save makes keeping the pool more practical.