Solar Panel Heaters

DustDevil · Mar 15, 2017

Hi everyone, been reading on installing a solar panel pool heater for a while and a few quick questions.

1. Is it reasonable to drive a solar panel heater off a sump pump? I have seen a few threads, but more about problems then successes. Install would be on a pergola 10ft above the pool, so checked out a few pumps with the needed head lift (~ 16ft). Biggest disadvantage I see is not having filtered water run through the panels. Biggest advantage would be not having to plumb 50ft of new tubing from current pool pump location.

2. I assume it is better for pumps to push then pull water, is this correct? That is, the pump motor is better situated as a submersible as opposed to an in-line pump on the pergola near the panels (pull-push system). Ultimately probably just need to buy 1 panel and see what flow is using different configurations but thought I would ask.

3. Has anyone had good success with ebay solar panels (eg. XLong Inground Above Ground Solar Energy Swimming Pool Sun Heater Panel 4 | eBay ). I see Helicol, Fafco, Aquatherm seem to be preferred but outside of the investment I want to make.

Thanks everyone for any help and for the awesome resource this site is.

JohnT · Mar 15, 2017

Welcome to TFP!

So many reasons it's better to use your pool pump. A sump pump isn't intended to run all day, and you need to run as much as you can to benefit from solar.

CJadamec · Mar 15, 2017

A single 4x10 panel will do very little to heat your pool most pools what size pool do you have? A 4x20 fafco pannel will run you around 200 from amazon or ebay which is "ok" for pools up to 24'. The panels you linked to have a lot of reviews saying they are prone to longitudinal splits on the tubs which lead me to pass them up on amazon there was a seller there selling (4) 4x12 panels for 170 which is a great deal but in my mind too good of a deal for there to not be an issue with them. Just my 2 cents as I just purchased my solar panel about a week ago.

mac4lyfe · Mar 15, 2017

I just bought these panels off of ebay. XLong Inground Above Ground 28 Solar Energy Swimming Pool Sun Heater Panel | eBay

The collectors are much larger than fafco or sungrabber. It's like only 22 channels along the 2 feet whereas sungrabber has like 150. If a couple of these channels start to leak it looks easier to plug but you're going to lose much more throughput versus plugging a little channel in the others. I'm thinking more channels equal higher efficiency as well but I haven't installed these yet nor tested. These panels are much more rubbery than the others that are pretty rigid. Time will see how long they last.

gwegan · Mar 15, 2017

For a whole host of reasons you should run off a pool pump. You can't have a submersible pump in a pool. So you couldn't swim with the solar running. You also need to use filtered water otherwise the panels will clog after the first month.

DustDevil · Mar 15, 2017

Thanks everyone for the replies. I am hoping to start with about 80 to 100 sq ft of panels, should have clarified. Link was more for brand then sq. ft.

From the reading I have done, seems 4-6 GPM is near ideal for most of these solar panels. Is that right?

To get the right head pressure though will probably need to run around 2000 rpm (based on Head (feet of water) = (RPM/350)² - GPM²/470). This would place GPM around 25-35 GPM. Not sure how to calculate in flow restriction of panels, or if you need to.

Seems the pool pump would be overkill to get the required head. All new to me, so please correct my understanding of the flow dynamics.

If correct, at 2000 rpm my old variable speed pump would run about 400W. Currently have a single speed but looking to upgrade.

So assume run 5 hours a day, that is ~ 2kwh each day. In AZ, on peak is $0.25 per kwh so about 50 cents a day to run. Not terrible but not good either.

A 12V, sump pump could be easily run off 5 amps (so about 0.06 kw). If run for 5 hours would be 0.3kwh and about 1.5 cents a day. Other advantage is you could probably run this off a 120W solar panel with easy, no converter needed and almost self-flow regulating (i.e. pump runs faster when more sun which is good).

What I can't figure out most 12v transfer pumps use garden hoses, so what kind of head loss or flow going from 3/4 to 1.5 inch pipe.

Is this reasonable or just a bad bad idea

- - - Updated - - -

CJadamec...if you have a link to 4 - 4x12 panels for 200 please send! Also teh reviews on the product I linked would be great, couldn't find any.

JohnT · Mar 15, 2017

Only pool approved pumps are safe for swimming. Plus the pump will burn up a few hours into the first day.

Synchronous AC motors, which most sump pumps use, aren't variable speed. They run at the same speed all the time.

Plus you'd need separate intake and outlet hoses for the solar which would be in the way and look like heck.

Not even worth considering.

Use a valve and bypass to adjust flow through the panels.

mac4lyfe · Mar 16, 2017

^^ John and gwegan are giving you the best advice. You only want to use pool approved pumps for long term use. I have used a sump pump to check panels for leaks, so it does work but I only ran it for several minutes at a time and I certainly wouldn't swim while the pump was in the pool. It can certainly be done (especially if you have a small pool) but the price of replacing the pump after it's burned out and the cost of replacing plugged panels because the water wasn't filtered first will most likely cost more than the savings gained. Plus my wife is none too happy with wires and hoses laying all over the place.

CJadamec · Mar 16, 2017

Sorry to take a while to get back but like the others said a sump pump is right out. Your pool pump is there to do that job already and is the proper tool for the job.
This is a link to the 4x20 panel I picked up it says sun quest but in the box is a Fafco panel.
https://www.amazon.com/gp/product/B015GBLSFS/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1

This is the link to the other ones I mentioned.
https://www.amazon.com/Koval-Powere...2&sr=8-11&keywords=Solar+Swimming+Pool+Heater

If you look closely to the pictures of the panels from other sellers you can find reviews for the same panels sold under different names. This is a link to reviews of the same panel design.
https://www.amazon.com/XtremepowerU...72&sr=8-4&keywords=Solar+Swimming+Pool+Heater

The Fafco panels have threaded header connections making the plumbing much more standard with off the shelf fittings. The cheaper panels use a metric header with no threads so you have to use a hose clamp to connect to them. That was another reason I spent a lil bit extra for the fafco panels.