Solar Panel Replacement / Update

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The efficiency of the panels is related to the flow rate but given you have a pretty large set of panels, it will probably deliver more than enough heat for the pool. The only issue may be that the pump run time will be slightly longer to get the heat gain than if the flow rate was higher.

But if you want to figure out where most of the head loss is:

What is the clean filter pressure?

What is the pump level relative to the water level?

Is all the plumbing 1 1/2" including the backwash valve?

Is there only one suction/return line to/from the pool?

What is the distance from the pool to the equipment and from the equipment to the panels?

What is the model # of the pump?

Is the bypass off so all of the water is going through the panels?
 
Ok, here goes, I have 2 pressure gauges installed now, and a flow meter that shows flow when solar is selected per the diagram above.

Equipment is: Jandy 2 speed 1.5 HP Flo Pro model FHPM 1.5-2, filter is a Hayward EC-75 Perflex DE filter, and the solar panels are 11 4x12 TechnSolis panels with 2 inch headers. Aditional Information the spring check valve on the solar return claims to have .2 psi of restriction, and the vane type flow meter states a maximum of 1.9 to 3.8 psi at 80 gpm (no curve information at lower rates that I have found, it is Universal Flow meter model MM with 1.5 inch fittings, it was an ebay deal)

All underground pipe is 1.5 inch, which includes 1 skimmer and 2 returns sharing the same 1.5 inch pipe back to the pump, all inside equipment room plumbing is 1.5 inch with the exception of a 2 inch stub on both sides of the pump totalling about 4 feet in length and the 2 inch solar diverter valve (steps down to 1.5 inch on both sides though due to existing plumbing layout limitation and my desire not to use a jack hammer) there is no backwash multiport valve with this DE filter, just a backwash / drain outlet with its own cut off valve and drain line . Almost all outside above ground plumbing for the solar panels is 2 inch, with the exception of the solar panel feet that transitions to 2 inch 10 ft after going through the wall from the equipment room.

below ground suction side pipe from skimmer to the pump 1.5 inch with a 35 foot straight run, return line is also 1.5 inch and is about 35 feet to the first eyeball, and another 30 feet to the second eyeball with 2 elbow fittings. Pump is located about 12 inches above water level.

Solar plumbing outdoors all 2 inch except note above has 70 ft to the panel feed point and 80 feet on the return totalling 150 feet (this is rounded to the nearest 10 ft), panel layout is as shown above with 2 banks, but instead of 10 panels there are 11, the extra panel is in the right bank, if my math is right the .15 psi pressure drop of the panel should roughly equal the drop found in the 45 feet of 2 inch PVC on the return from the left bank of 5 panels, not counting fittings at the ends which should cancel each other out.

Pressure readings with clean filter are 20 psi at the filter and 5 psi at the feed side of the solar panel, both gauges mounted at a about 2 feet above ground level, top of panels at about 15 feet above ground level. Measured flow at the flow meter about 48 gpm, all water going through solar panels.

thanks for the help, Ike

p.s. it does seem the filter is a major restriction here, but I am still wondering if my flow goals would be improved with an additional return line, and or potentially replacing my skimmer and upgrading to 2 inch on the suction side.
 
You are losing 15 PSI from the filter to second gauge which is pretty significant and much more than I would expect. It could be in the filter or the plumbing but it seems a bit high to me especially since the flow rate is so low.

Just a back of the envelope:

15 PSI = 35' of head

At 48 GPM, that is about 4x what a DE filter with a 1.5" backwash valve would typically cause. So unless you can figure out what is causing so much pressure loss, changing the return won't help much.

Again, are you sure you have the bypass completely shut off forcing all of the water through the panels?
 
Yes, I am sure that all flow is going through panels, and this is my second Hayward EC75, the first one was destroyed by my roofers last year (long story, simply put they took it upon themselves to "clean" it after dumping all sorts of debris into the pool), both had similar clean pressure readings, it was not until I just added the second pressure gauge down steam that I realized just how much flow resistance these filters have. Specs are here http://www.hayward-pool.com/prd/In-Grou ... 5516_I.htm
 
I don't have any head loss data on that particular filter but just based on the drawings, more than likely that is what is causing all the head loss. If you want more flow rate, you will need to fix that first but it may not be worth it either.
 
I guess I will take it one step at a time and live with things for now on the flow limit, it was one of THOSE days today, which fits in since it was one of THOSE weeks last week, including but not limited to having no air conditioning the last 3 days (well almost none, just a portable one I bought for emergency use on the generator a few years ago) as the fan on the central air conditioner outside unit failed catastrophically (sheered off at the hub, then running off balance sheared the mounting screws), today I get the solar controller hooked up and everything running then BOOM a couple of hours later power surge ZAPPED the solar controller and a TV. Solar controller may be fixable looks like it blew a filter capacitor, along with the fuse and maybe the LM317T voltage regulator. So I guess I will be going to Radio Shack in the morning and hopefully they will have a 317T.

Ike

p.s. thankfully we had a cool front come through Friday, with luck the replacement fan will arrive Monday
 
Isaac-1 said:
Yes, I am sure that all flow is going through panels, and this is my second Hayward EC75, the first one was destroyed by my roofers last year (long story, simply put they took it upon themselves to "clean" it after dumping all sorts of debris into the pool), both had similar clean pressure readings, it was not until I just added the second pressure gauge down steam that I realized just how much flow resistance these filters have. Specs are here http://www.hayward-pool.com/prd/In-Grou ... 5516_I.htm
Click to expand...

We recommend changing DE filters to cartridge filters when installing solar pool heat. A clean DE filter adds more back pressure, and a dirty DE filter increases the pressure quicker than a dirty cartridge. I can't overstate the importance of proper flow in a solar pool heating system (quantity and balance).
 
If the DE filter is sized appropriately, then the flow should be just as high as a cartridge filter. And if the filter is backwashed as we recommend, then flow will not be reduced too much. If course if a cartridge was undersized, then that too would increase pressure and lower flow rates.

Never had a problem with my DE filters on either of my setups with solar.
 
jblizzle said:
If the DE filter is sized appropriately, then the flow should be just as high as a cartridge filter.
Click to expand...

True enough, but we rarely see adequately sized DE filters around here. They also get dirty faster in my experience - or more accurately, the flow rate is reduced faster as the DE filter gets dirty.
 
Thanks for weighing in,

On the topic of flow, do you feel 4 - 4.3 GPM per 4x12 panel is critically low? As this is my current range between dirty and cleaned filter? Published minimal flow is 3 GPM and max is 10 GPM, recommended is 4.95GPM, I am just not sure I trust their numbers since minimum varies with panel and header size, but max and recommended stay the same at 4.95 GPM for 4x8 through 4x16 panels.

Thanks Ike
 

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Isaac-1 said:
Thanks for weighing in,

On the topic of flow, do you feel 4 - 4.3 GPM per 4x12 panel is critically low? As this is my current range between dirty and cleaned filter? Published minimal flow is 3 GPM and max is 10 GPM, recommended is 4.95GPM, I am just not sure I trust their numbers since minimum varies with panel and header size, but max and recommended stay the same at 4.95 GPM for 4x8 through 4x16 panels.

Thanks Ike
Click to expand...

They should be able to supply a curve. For FAFCO panels, there is not a dramatic drop off in efficiency until you get down to the 2 GPM/panel range. 4 GPM is close to optimal. They may have the same GPM rating because the curve is pretty flat at that point typically. I would say if you are shooting for 4 GPM with any brand or length panel, you will probably be okay. Remember that these "optimum" flow rates are based on test conditions, so the actual efficiency under given circumstances may vary. You don't want the water flowing so fast that all of the minimal heat gain is lost on the way back to the pool, and you don't want the water flowing so slow that the heat rise is great because the panels lose efficiency as the water temperature in them increases (there is a point of diminishing returns).
 
Jason, you made a comment about wanting a job, it looks like I may be getting into this solar heating stuff more than I planned, since installing these new panels a couple of weeks ago I have had 2 neighbors ask which solar installer I used, and when I told them it was a mostly DIY project they have asked me to help them layout systems for their pools.

Ike
 
Isaac-1 said:
Jason, you made a comment about wanting a job, it looks like I may be getting into this solar heating stuff more than I planned, since installing these new panels a couple of weeks ago I have had 2 neighbors ask which solar installer I used, and when I told them it was a mostly DIY project they have asked me to help them layout systems for their pools.

Ike
Click to expand...

Haha. The whole solar pool heating industry runs on word of mouth. I'm not a bit surprised. Once people show their neighbors how awesome it is, they invariably want it!
 
Well I think I have it all going right now, hard to tell for sure though as I did not get it all working until after dark tonight, and of course we have 70%+ chance of rain the next 2-3 days.

Stop reading here if you want, a bit of a rant / saga follows

As I mentioned a few messages ago I had just managed getting everything connected to the existing solar controller last weekend when we had a power surge that fried the controller (replacing the fried voltage regulator chip did not fix it either, it just blew again when power was applied), so I thought no big deal I will just order another bare Aqua Solar model AQ-SOL-LV-TC (the one with the built in pump timer), not the whole kit with sensors and actuators, I find a place that shows them in stock at a reasonable price (just over $225 +shipping), well it turns out they were out of stock until June, it seems everyone was out of stock until June for ALL variants of the AQ-SOL, at least everyone that did not want full retail at $450+, then after much searching I find Amazon has ONE base version (ships with no sensors, actuators or relays) of the AQ-SOL-LV in stock for $225, so I order it, with hopes of transplanting the fried circuit board (note I do have electronic equipment repair experience, certifications, etc. disclaimer, don't try this at home, etc.) Well it comes in today, I take it out of the box, and it is ALMOST what I need, same basic circuit board in the control box, no cut out for the timer, but otherwise MOSTLY the same. Here is the big kicker they did not populate the header pins for the timer connector on the circuit board, every thing else is there, even the little surface mount resistors / capacitors that the traces from the header pins would go to, just NO CONNECTOR to plug the timer into, even the part number is the same on the circuit board. So I end up spending about an hour of my time tonight with a soldering iron transplanting the header pins off my dead circuit board onto the new one (I am sure voiding the warranty in the process) all because someone decided it was best to save around a penny for a little header connector, probably less than a penny in bulk)

Ike

p.s. I know I had no reason to expect them to use the same circuit board other than it makes sense from a design standpoint, but to populate EVERYTHING but the one cheap header was a bit annoying, I can see leaving off an expensive IC that might not be used on the base version, but HEADER PINS that are used in another production model....
 
Hi I just found this thread, very good info for me as I'm deciding if to repair or replace my 30 year old solar system. I have stock 2" PVC up on my roof now, do I need to paint that, and if so, is there a special paint to use?

BTW, I thought the last post on the first page was May 5 of 2014, looks like this thread is a year old, sorry if it is all outdated now.
 
Its ok, but you should start your own thread on your project, tell us about your situations and what you are considering, etc.

Ike

p.s. if that PVC is 30 years old I would suggest replacing it, in my update I had a through wall section of 1.5 inch PVC that I was replacing with 2 inch, in the process of pulling the old pipe out of the wall, I found the PVC cement had degraded to the point I was able to pull the ball valve off the end of the pipe.
 
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