confused about solar panels (or mats)

[farmgirl]

Setting up pool today, some of u might remember last year's arguments with DH about two panels staying hot (ie, no water flow thru them). to prove his point today, he had me look into each header pipe of each panel, to show me the center baffle, or diverter, where the water pressure should force flow up into the panel. i could see that the diverters are NOT solid, but have smaller holes in order to send part of the water up thru the panel, and not create immense back pressure. (Sort of like a washer placed in the center of the header pipe) is this right? or should the baffles CLOSE off water flow through the header pipe COMPLETELY until it makes a u turn and comes back through the panel? One of our panels has NO baffle AT ALL????? Could this have been last year's problem? i read that solar panels made for in ground pools have no baffles at all. i heardthat sometimes they can fall out and get lost. does that mean the panel is now useless? If not, can this panel still be used in conjunction with the others? should i replace it? is there any way to repair it? guess i need a class on "solar pool heat 101".

[farmgirl]

Since no one has replied to my question, perhaps i should assume that i did not make myself clear. Oh well, it is easier for me to "show" than to "tell. To simplify my question pertaining to the flow restrictors in each header pipe of the solar panels.....has anyone ever put a new flow restrictor on a solar panel? Would it be ok to just use the panel WITHOUT the flow restrictor? I understand that in ground pools require panels WITHOUT flow restrictors. Why???? I just need to know A: how to fix the panel, or B: can i go ahead and incorporate this panel into the system along with the others? ANY help will be appreciated. Thanks!

[chem geek]

There are different kinds of solar panels for use with pools. Even with an above-ground pool, the panel design may be similar as with an in-ground pool except that they are usually longer (in-ground pool panels are usually roof mounted so are typically sized at 4 feet by 8, 10 or 12 feet while in-ground panels are typically mounted at ground-level and are frequently 4 feet by 20 feet. This link shows in-ground [EDIT] I mean above-ground [END-EDIT] pool solar panels from FAFCO. These are the "many small tubes" kind of panels and are the same, except for size, as their in-ground panels. The flow rates for each panel are the same as for their in-ground pool panels, namely a minimum of 3 GPM, recommended 4 GPM, maximum 8 GPM. So clearly if only two panels are used then there must be a diverter since the flow rates from typical pumps are much higher than 6-16 GPM (assuming two panels are used in parallel).

Do you know what brand of solar panel you are using? Perhaps we can find its specs on the web and figure this out. Also, when you were running water through your panels, if they were hot from the sun before the pump went on and then stayed hot, then water wasn't flowing through them with enough volume. If they cooled off (to ambient air temperature) when the pump went on, then they are working at least somewhat properly.

Richard

[farmgirl]

We have a total of four 2x20 panels, including the one that is missing the diverter in the header pipe. If we go ahead and hook it up, will it work ok? We were thinking of trying to following configuration:


return====||>>>>>>>>>>>>>>>>l l
||<<<<<<<<<<<<<<<<||
l l
||>>>>>>>>>>>>>>>>||
||<<<<<<<<<<<<<<<<====pump


According to everyting I have read, the more water flow you get going thru solar panels, the better. So why do they put in those diverters in the first place? Would you not get better water flow without them, if the panels were set up and plumbed correctly? As u can tell, science was NOT my best subject.....LOL!

[farmgirl]

well, my diagram screwed up when I sent it to the forum....let's see if i can try again:


pump=====ll>>>>>>>>>>>>>>>>>>ll
ll<<<<<<<<<<<<<<<<<<ll
ll
ll
ll>>>>>>>>>>>>>>>>>>ll
ll<<<<<<<<<<<<<<<<<<ll
ll
ll
ll>>>>>>>>>>>>>>>>>>ll
ll<<<<<<<<<<<<<<<<<<ll
ll
ll
ll>>>>>>>>>>>>>>>>>>ll
return====ll<<<<<<<<<<<<<<<<<<ll

We figure that this way, if we cap off the ends with the diverters, water will be forced to path of "least resistance", and just flow one way through each panel individually. What do you think?

[farmgirl]

i still cannot seem to get the diagram lined up correctly, but maybe you'll get the idea

[farmgirl]

last year i had 2 hot panels and two cold panels. The hot panels (not working properly) were the two on the inside, cooler ones were on both ends of parallel configuration. They are all the "sungrabber" models, a set of four 2x20 panels. my main concern is of cours maximum efficiency, but also whether or not i can use the panel that is missing the diverter (flow rate resrictor) in the header tube.

Last year i had this:
pump========
cold==================ll
warm=================ll
warm=================ll
cold==================ll
return========

I would like to repeat that all header pipes with diverter discs were at the return and pump side of this setup. We double checked that!

[farmgirl]

my diagrams are just making things worse. They are not going thru to the forum as i have typed them. Anyhow, we had standard parallel setup with return and pump on same end, and all panels capped off on the opposite end.

[farmgirl]

Code:
||>>>>>>>>>====return
||<<<<<<<<<<<<<<<<||

||>>>>>>>>>>>>>>>>||
||<<<<<<<<<====pump

Maybe this will be a little clearer....whew!!!

[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