How to direct water to solar panel

[mxcolin]

I have a small DIY solar panel that I'm going to use to add some extra heat to my pool, I understand all the economics of a DIY solar panel etc. that's not what I'm concerned about it's the mechanics of the flow I'm wondering about. I'm going to feed water from the pump return to the solar heater, my question is regarding how:

Option 1: I split the water coming out of the chlorinator running one side to the heater and another side away from the heater, then combine both of the flows further up the line and into the same inlet that returns to the pool.

Option 2: Same as above but rather than combining the water upstream I return the warmer water through a separate return.

For option 1 I'm not sure if the chlorinator should come before or after the solar heater, or if it even matters.

 

[PieterS]

I think you could do it either way - whatever is easiest from a plumbing perspective. I would almost just stick to option 2 for simplicity if you have a good way to return the heated water to the pool or don't mind just having an extra hose going into the pool.

As to before/after chlorinator - I would lean towards after the chlorinator so as to not mess with the flowrate through the chlorinator (although I assume whatever you divert for the solar heating would be a small amount). I don't know if the concentrated chlorinated water coming out of the chlorinator matters for the solar loop?

So no great answers - just more to consider!

 

[mxcolin]

Yeah, I'm leaning towards option 2. I have a good way to return water to the pool and no issue having an extra hose going in.

 

[Zmann]

Pic of your DIY solar ?
I have a flat roof and I am going to build a few of them , probably the pex under glass for the first try but still planning

 

[mxcolin]

This is my first attempt, not completely finished but I'm happy with it so far.

 

[Zmann]

thanks
I see you been searching on the interwebbs also lol

the dowels and irrigation tube is cheaper than pex and may be a better option

I just happen to have access to 7 sheets of 5x5 glass so I was using that for my size

 

[mxcolin]

It started to get expensive as I added up the materials and the items I didn't have that I needed to buy to complete it, plus mistakes/things I didn't need. Could build a new one for probably 60% of the cost. Tested it yesterday and got about 14 degrees of extra heat at a pretty decent flow rate. We get a LOT of sun, so I'm pretty hopeful. I've seen people build these on YouTube in places with almost no sun and get some decent results. I may daisy chain a pre-made panel also at some point. Every time I look at reviews on them, however, it's almost always bad. Full of leaks and problems.

 

[Zmann]

if they had premade panels at a fair price I would try them but decent ones are pricey and need a mounting system since they can blow around , the DIY have some weight and I don't think they will need much mounting consideration on my flat roof

I am ordering my valves and backflow preventer so I can get the plumbing run up to the roof ,, then I will start my panel build

 

[Newdude]

if they had premade panels at a fair price I would try them but decent ones are pricey

OP has 4500 gallons and although +14 degrees is a impressive gain, the flow rate through a garden hose will not likely add much to the pool that isn't erased overnight.

With your 31k gallons, you'd be 'spitting in the ocean'.

However, i am a huge fan of backwoods engineering, so Bravo @mxcolin !!!!

 

[mxcolin]

Yeah, you're right, I did the project mostly because I enjoyed it and wanted to see how it would work. I'm under no illusions that it's going to be a massive difference-maker, maybe in conjunction with my solar blanket, it will add a few degrees. We'll see, hoping to test it in April. We do get a lot of sun as I said.

 

[Newdude]

I did the project mostly because I enjoyed it and wanted to see how it would work.

And for that, *and* it worked.

You have alot going for you with the pool size and location. Keep us posted.

 

[IUsedToSail]

My kiddos have been begging to build one of these as a Home School science project. Anyone else have some real world results?

I need to replumb anyway for my new cartridge filter, I already bought the T's and fittings to connect it to the system but am on the fence whether I want to build it or not. We already have a 406k BTU Raypack pool heater, however with gas prices through the ceiling it probably wont be getting much use this year. Just firing it up costs like $7. ;-)

 

[mxcolin]

I have just hooked mine up and will report my findings in a few days. Lots of sun ahead so let's see what I can get out of it

 

[mxcolin]

So I have my setup complete, it's very unseasonably cold and overcast for us at the moment but that's about to change, so hopefully get some results soon. Even now the water at the heated outlet is a few degrees warmer than the pool water. The one thing I've noticed after all this is that my pump is now probably a little under-powered, that being said I'm very happy with the way the plumbing turned out and not a single leak.

 

[PieterS]

Looks pretty good!
What is the black/grey cartridge in the middle of the picture - is that an additional filter?
How are you regulating flow through the solar loop?

 

[mxcolin]

It's a chlorinator, one of my biggest issues in previous years has always been forgetting to chlorinate the pool so I wanted to automate it. The flow from the 1-1/2 PVC to the garden hose seems to regulate the flow more than enough. If anything I'd like a greater flow rate.

 

[PieterS]

Right - got it, makes sense. I use the Intex chlorinator myself and have been pretty happy with it. Definitely prefer it over lugging chlorine!

I've been thinking of building a few coils myself. Fully understand likely doesn't make much difference, but I'll tell the kids it does Would love to build something with a little solar panel - would only run when solar power is enough to run it... that way I don't' have to tee off the pump, and don't have to extend my pump time just to run the solar loop.

I upgraded my intex pump/sand filter after the 1st year - the combo supplied with the pool is barely adequate!

 

[mxcolin]

Yeah, it's not likely to make a massive difference but I loved making it

 

[bjmsam]

I've been thinking of building a few coils myself. Fully understand likely doesn't make much difference, but I'll tell the kids it does Would love to build something with a little solar panel - would only run when solar power is enough to run it... that way I don't' have to tee off the pump, and don't have to extend my pump time just to run the solar loop.

That's what I did:

Encouraged by this post (and not discouraged by this post or this post or myriad other posts), I also built a 4-ft x 8-ft solar water heater panel using most of a 500-ft roll of 1/2-in polyethylene irrigation distribution tubing and spare wood that was taking up room in my barn.

A spare photovoltaic panel stepped down to 12V powers a small diaphragm pump to circulate water through the thermal panel. Fun project!

Note for anyone interested: The water in my solar heater is circulated by a DC pump powered directly from a PV solar panel. A 360W transformer is used to convert the 48VDC panel output to the 12VDC pump input, but when the panel is shaded or the sun is setting, the pump pulls down the voltage until the transformer switches off, the panel recovers, the transformer switches back on, and the cycle repeats about once every second or two, which is undesirable. A cheap Low Voltage Disconnect (LVD) in discharge mode connected between the panel (battery) and transformer (load) eliminates the problem by activating the pump when the panel generates more than 46VDC (near rated output in sun), deactivating the pump when the panel generates less than 40VDC (shading or sun angle), and waiting five minutes before attempting to reactivate.

Pump
Transformer
LVD
Have fun!

 

[setsailsoon]

m,

Very cool little project. If you decide to mess with this more remember flow is generally more important than temp at the outlet of your heat exchanger. You want turbulent flow. At this rate the flow is higher and outlet temp is not max but overall BTU's transferred is maximized. There are calculations the flow regime using the Reynolds number. You may have to dig a little bit on Google. Or you may even be able to find a pdf copy of a manual called Flow of Fluids by Crane. They had some very neat nomographs that we used before calculators were available. On second thought you may want to forget this idea... there's probably an app for that!

Chris