Large Scale Solar Installation

[pool250]

I am thinking about putting in a large solar water heater.
I am plumbing the new pool in the next couple of weeks so I need to know if I have to put in separate pipework
for the solar or if I can use the main pump and line.
The plan is to put in 2 or 3 times the surface area of the pool (28sqm) in black pvc pipe; about 90sqm, coiled on a piece of ground about 6ft higher than the pool/pump and about 30ft distance.

I need to find out how effective this kind of larger installation would be in heating the water in winter.
The average daytime winter temp is around 60F and night time around 50F: no snow, night time frost is rare and light, typically winter daytimes with full cloud cover.
If the benefits of putting this size of system would not extend to keeping the pool sufficiently warm in winter then I should really only put in sufficient pipe to extend the shoulder seasons.

thanks

 

[Bama Rambler]

As a rule the coiled pipe installations aren't nearly as efficient as the standard mfg'd units. You'd probably be money ahead to buy mfg'd units unless you have several thousand feet of black poly laying around.

You can use your main filter pump to run the solar collector system.

 

[pool250]

If I get panels they would have to go on stands I imagine as I have no spare north facing roof and I suspect that they would corrode badly left on the sandy ground here.
The cost of pipe works out about $1700 for 90sqm, I am guessing that panels to get equivalent output would be considerably more here plus there is the cost of the stands which I could have made up fairly reasonably.

The big question is, whether it is poly pipe or a smaller area of panels, is this sort of sized solar going to heat up the water sufficiently to keep the pool open for a good chunk of the winter here?

 

[bk406]

as I have no spare north facing roof

I saw this and thought to myself why in the world would he put solar panels on the north face of the roof. Then I remembered your under the equator!

 

[pool250]

spare north facing roof space is becoming a precious commodity down here......you cant even give away the south facing stuff!

 

[mas985]

The average daytime winter temp is around 60F and night time around 50F: no snow, night time frost is rare and light, typically winter daytimes with full cloud cover.

Without the sun, how do you expect to use solar?

 

[pool250]

The average daytime winter temp is around 60F and night time around 50F: no snow, night time frost is rare and light, typically winter daytimes with full cloud cover.

Without the sun, how do you expect to use solar?

yes that is what I thought too.
I hope Jason wont mind my quoting him from my Pool Plumbing Layout thread: "Solar can be extremely effective if you have enough surface area of solar collectors. Even a small area of collectors will extend the season several weeks, and at the other end of the range, with two times the surface area of the pool you could swim most of the year".

To my reading this would mean that given enough surface area of collector, winter conditions which were reasonably mild such as I have here, should extend the swimming period considerably, regardless of the lack of brightness/heat, but I may have got the wrong impression.....

 

[mas985]

Unfortunately, there is no solar without the sun. I believe that Jason's quote was assuming there is sun. You can have some heat gain with just the air but then the air must be warmer than the pool.

I have 450 sq-ft panels on a 550 sq-ft pool and if the weather is right, I can get 80+ water from March through October. But the sky has to be clear and the wind not too strong. Otherwise most of the heat is lost. Also, you need to have a good cover to reduce the heat loss.

If most of your winter has cloud cover, then I would say forget it. Just plan for the sunny months.

 

[pool250]

Reckon its that Australian Tourist Board at work; they have convinced the world that the sun shines all year in Australia......if only.

 

[pool250]

Cant get sunshine hours statistics for here. can anyone give me an idea of what size of collector would be best for a 28sqm pool, with a fairly mild winter.

 

[dmanb2b]

You can lay Fafco panels on the ground without a problem, unsighlty yes, but they will not corode as they are plastic. You do run the risk of a rodent chewing through 'em , but I've got field mice, skunks, wild turkey, deer, rabbit and Raccoons and so far so good after 2 seasons. Just lay some landscaper's cloth under them...I used some leftover tyvek I had laying around

PS...in my case the south side (your north side) faces away from the yard, so I could acre less what it looks like behind the pool, and as for when you are around the pool, most people get over the look of then panels on the ground vs the warm water they are swimming in

 

[dmanb2b]

ps...one 4x20 fafco panel would do just fine on a 11k gal pool but if you have room for 2...even better.

 

[pool250]

You do run the risk of a rodent chewing through 'em , but I've got field mice, skunks, wild turkey, deer, rabbit and Raccoons and so far so good after 2 seasons

I have these guys bouncing around all night and some of them are 5ft tall; reckon they might put a paw through those panels.

 

[dmanb2b]

awe...they're about the size of my retriever

Just kidding...I guess deer hooves would have done mine in ...the panels are pretty tough...I've walked on them with boots on. But little raccoon teeth...they've gone through our garbage cans at time

here is a pic of mine if it helps

I've since added a 2nd panel

 

[Bama Rambler]

Yeah the roo would be bad for the panels but it will for the coil of pipe too so that's a wash. As Dman said, laying the panels on the ground is fine and since it's sand that's even better. However, whichever system you go with you're gonna have to have sun at least a few hours most days.

 

[mas985]

Cant get sunshine hours statistics for here only this. Can anyone convert these figures into available sun hours for best sizing for solar collector ie large enough to take advantage of the usable sun weeks and no larger so that the extra collector capacity isnt contributing, for a 28sq metre pool?

Mean daily solar exposure (MJ/m2)
The averaged amount of daily solar energy reaching a specific location on the Earth’s surface in a calendar month or year, calculated over the period of record. The solar exposure provided in these statistics has been estimated from satellite imagery. Divide the values by 3.6 to convert from units of megajoules per square metre (MJ/m2) to kilowatt-hours per square metre (kWh/m2).

So the pool is 28 sq-m? That is 300 sq-ft not 90. That makes a lot more sense given the pool is 11,000 gallons. But then the solar panel coverage is 100%.

BTW, the same web site contains other stats such as mean daily sunshine, number of clear days and number of cloudy days.

 

[pool250]

BTW, the same web site contains other stats such as mean daily sunshine, number of clear days and number of cloudy days.

Yes it does but not for this location; they dont collect all of that data for every location and they dont collect hours of sunshine for here, unfortunately.

I was figuring around 3X the surface area which would be about 90sqm,

 

[pool250]

ok, so just to confirm. A second pipe circuit and low flow pump (say around 25lpm) isnt going to be required for these small diameter tubed rubber panels or other type of collector?
The rest of the details can be worked out when the pool is finished but for now I have to be certain that I dont need to put in a separate pipe circuit on the pool.
thanks

 

[Bama Rambler]

No second circuit needed. Just a bypass (which you will do anyway) is all that's required. Your main pump will handle the solar fine.