confused about solar panels (or mats)

[chem geek]

The specifications for the SunGrabber solar panel may be found at a link to a PDF file on this web page. It says that the minimum recommended flow is 1 GPM per panel, the maximum recommended flow is 4 GPM per panel, and the normal recommended flow is 3 GPM per panel.

Thank you for your diagram which shows that these panels are currently hooked up in series, though that doesn't make much sense since it is less efficient and would require a bypass for most of the water from the pump to go to the returns directly (do you have such a bypass)?

The panels will hold up to 30 PSI for normal operating pressure (maximum intermittent is 45 PSI). So that's about 69 feet of head for the high-end of the range of normal operating pressure. I don't know what size of pump you have -- if you know it and the brand, then I can look up the pump curve (unless you've got the manual that should have it).

Unless you had some sort of bypass taking some of your pump output to the returns directly and only feeding some of the flow through the panels, then it would seem to me that your pump has blown out parts of your panel (i.e. the diverter) due to higher than recommended GPM and may even exceed the panel's PSI limits.

The specifications for these panels say that the maximum recommended flow per panel is 4 GPM. Hooking them up in series limits the total flow for the entire system to be the same 4 GPM, but the temperature gets higher as it goes through each panel. This is less efficient since you want the panels to stay cooler. It would be better to hook them up (or as many of them as is reasonably possible) in parallel instead of in series. That is, connect the tubes at one end to each other. With your four panels, that will allow for 4x4=16 GPM total to flow through the system with the panels all remaining relatively cool for best efficiency.

On the FAQ page it says:

How big is the SunGrabberTM System for Above Ground Pools?

Each system is approximately 20 feet long by 4 feet wide, consisting of two 2'x20' solar panels (coupled together with a 3 ½" coupler).

So it sounds like you have two systems which should be plenty for warming your 24 foot round above ground pool.

Having all systems in parallel would look like the following:

  Pump
    ||>>>>>>>>>>>||
    ||           ||
    ||>>>>>>>>>>>||
    ||           ||
    ||>>>>>>>>>>>||
    ||           ||
    ||>>>>>>>>>>>||
                Return

I believe you were showing the systems being connected in series as follows:

  Pump
    ||>>>>>>>>>>>||
                 ||
    ||<<<<<<<<<<<||
    ||
    ||>>>>>>>>>>>||
                 ||
    ||<<<<<<<<<<<||
 Return

If one or more of your panels has a broken diverter, then that panel will likely have less flow going through it if hooked up in parallel, but you said your panels were hooked up in series so I don't see how a missing diverter would cause any problem. There would be full pressure along the entire length of pipe at the end of one panel and the water had to flow through the panel and through all other panels since in series there is no where else for the water to go. So, I'm confused.

Richard

[farmgirl]

panels are currently hooked up in parallel. series hookup was an idea that we found out will not work too well. called fafco last night, and it turns out seller accidentally sent me 3 above ground panels, and one in ground panel. i assume that is the problem. they are going to replace it with the proper one....hope that solves the problem!!! any other ideas for maximum solar efficiency??? thanks. you've been a great help.

[farmgirl]

Well, it has been 3 days so far, and Fafco has not returned my calls. Anyone else ever had to deal with their customer service reps? So far, they have been very nice, but I have the feeling perhaps they are trying to ignore the problem.....GOSH! I hope i am WRONG!

[matt4x4]

Hi Farmgirl,
I think I explained this to you last year....
First off, there's no difference between IG and AG panels, when looking at the kit, the difference lies purely in the accessories they soak you another 100 dollars for when getting the IG panel, however, panel costruction and operation normally does not differ.

edit...
Ok, after trying to get the make of my panels, I came across some info regarding certain companies and different construction between IG and AG - Sunheater by smartpool, does things a bit differently, they use open manifolds on both ends, thus utilizing each panel in a one directional flow, essentially the panels all get tied together in parallel on one end to feed and the output sides all get tied together to collect back to the pool - this should make each panel's efficiency pretty much equal seeing that the water on the input side is the same temp for each panel.
Here are their instructions for both the AG and IG panels - hope this helps some........it sounds like your 4th panel is like thse IG from this Company...

http://www.smartpool.com/website/sun...%20English.pdf aboveground

http://www.smartpool.com/website/sun...%20English.pdf inground

end edit

When looking at the split manifold panel, there is a header manifold at each end of the panel, the 2 oposing headers are different internally.
One header has a SOLID block in the middle, this is the input/output header, water flows in and gets forced up half the panel because the block will not allow water straight through, once it reaches the other side of the panel, it enders into the open header (which should have caps on either end), this header does NOT have any blockage in it, the water from half the panel fills this header and pushes down the panel in the opposite direction, going back to the input/output header. Now the water reaches the input/output header on the previously dry half, and flows out the pipe, this pipe either gets connected back to your pool return or to the input/output header of the next panel and the process repeats itself.

Air pockets play a big part in the functionality of these panels, if air gets trapped in the open header, it may render a portion of that panel useless, the only way to get rid of trapped air is to place purge valves at each panel's highest point, depending on how the panels are mounted, this can mean several valves.

The most efficient way I found when mounting panels on a roof is side to side, feeding at the very bottom, with a checkvalve (automatic one way valve) in line to stop gravity from draining the panels backwards when not under pressure, this will allow the air to travel upwards working itself up and out of the panels naturally, once the air is purged from the panels, it will stay purged since there is a check valve at the input on the bottom.
Thihs method also only requires one air bleeder valve at the top where your panel meets your return line going back to the pool - this bleeder will automatically purge any air that makes it to the top of the panel, but not allow any air back into the system.

I think I drew a diagram last year, but can't find it on my PC.