Solar Heater on a Flat Roof?

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W

wiscousonian

0
Mar 17, 2010
80
well after a great first season I'm already looking forward to the next! I'm so thankful for all the help on here and getting me up and running with my first pool! Below are a few photos later in the season.
We went form this:
12-18-09-3.jpg

03-pool-3.jpg



To This:


7-30-10-59.jpg

7-30-10-65.jpg


I'm exploring the idea of adding a solar heater...I'm a pretty handy person but Ive got questions about this. I plan on just getting some panels and plumbing everything myself, putting it on my flat roof and making everything able to dis-assemble to remove it from the roof in the winter. So my questions are as follows:

1. I've read good things about some panels on ebay, And another i have bought the same brand (sun grabber) from a retailer instead of ebay. Specifically these on ebay. Whats your thoughts on these? I'd plan on getting 2 panels this size.
2. Do these need to be mounted to some type of rack so that they are tipped, even though I've got a southern exposed flat roof?
3. The best location on my roof is probably about 40-50' from the pump, Ive got a 1 1/2hp pump now, Should this be enough? i know this is a guess.
4. I'm assuming something like this is going to need to be secured to the roof? Thats going to be hard on a flat roof where penetrations to the rubber is a bad thing...guessing this means some kind of rack?

Any other questions i should be asking? I've estimated that i've got about 600sqft surface area.

It looks like the panels will be ~175 each (from ebay) + some plumbing pieces and this project should easily be taken care of for less than $600 (unless i need to build a rack of some type) yes? I'd really like to add a heater to my pool just to regulate the temps during the season, plus possibly provide an earlier open and later close.
 
I think you can get by without tilting the panels. For most of your swim season the sun will be nearly overhead. You'll have to anchor them somehow to avoid wind issues. I don't have a clue how to tell you to do it though, unless you could build a rack that spanned the whole roof or if you could lay some kind of rack directly on the roof.

Your pump should be plenty. You get back most of the energy used to raise the water when it falls back down, so you'll just be overcoming the length of pipe for the most part.
 
so are those type panels worthy of their price or should i be looking form something else?

Still not sure what to do about the anchoring issues....I could build a flat rack that could site on the roof, although wind would also get under that also, so that does not solve much.
 
I'm certainly no solar expert, but I did some research last year and ended up installing 6 - 4' x 12' aquasol panels on my roof. It was a very standard setup on a sloped composite shingle roof, so I can't offer much advice on your flat roof application. Perhaps you could strap it down and secure the straps into the wood fascia boards or eaves so you don't have to penetrate the roof? Maybe some sort of industrial grade tensioners/bungee cords attached to both ends? I'm not sure how this would affect the longevity of the panels as the tension required to keep them flat might be more than the panels are designed to withstand. Maybe this would be a good argument to build a rack system to withstand the tension. Just throwing out ideas here.

As previously mentioned wind is probably the major concern and my 4' x 12' panels are essentially secured at each panel corner with 2 lag screws, plus two straps horizontally across the panels with lag screws at the ends and between each panel. I think in total ~35-40 1/2" lag screws.

As for SunGrabber panels, I never really did determine any quantitative differences between SunGrabber and some of the more expensive brands like Fafco, Vortex, etc. I ended up going with Aquasol because they were somewhat inexpensive, had some good reviews, and the 4' x 12' was a good fit for my roof. I've heard the 20' SunGrabbers can be difficult to keep straight, especially on a sloped roof, and my panels are very visible from the front of the house so I wanted them to look nice. Perhaps not an issue with a flat roof.

As for sizing I'd recommend running some calculators online, like this one: http://www.solardirect.com/pool_heaters ... ulator.htm

160 sq. ft. of solar panel does seem somewhat on the small side to me, of course depending on your region and surface area. My pool surface area is about 400 sq. ft. I ended up with 280 sq. ft. of collector area, that's all my roof could fit. This gives me about 3-4 degree rise in temperature at 40 GPM and will raise the temperature of the pool about 5 degrees on a good full sun day. In the summer w/out a solar cover (which helps a lot) I was maintaining anywhere from 80-90 degrees. This summer I will try using a solar cover to hopefully keep it closer to 90.

Good luck!
 
dwichman, Thanks for the help.

According to the calculator i need about 320 sqft of solar or about 4- 4x20 panels! That seem like a lot of panels! I've got roughly 520 sqft surface area.

I'll have to do some thinking about mounting the panels still... Will I be able to simply roll these back up again for storage in the winter or will they get brittle in time? If i should not be rolling them seasonally then possibly a mounted option is going to work best to make sure they stay put from the day i get them, Although moving a 20' panel will come with it's own issues! I can't possibly be the only one that has these type of requirements.
 
I would get all the panels you've got room for.

One thing to consider is that if you mount them flat, they won't drain when the pump is off or you don't want heat. The problem with that is that the water that remains in the panels can get hot enough to damage some panels. Needs to be kept in mind with your planning and when choosing panels.
 

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Ok so i thought about a rack, PVC will probably be the best option because it will be light, easy to disassemble for storage, and pretty cheap. Here are my rack plan ideas posted below:

Top View:
rack-top.jpg


Side View:
rack-side.jpg


If I use tee's as feet it will give me a place to run a rope through the feet and attempt to hold it in place in strong wind.
 
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