Solar Sizing advice

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jeffblue

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Oct 20, 2015
81
Huntington, NY
Hi all, looking to get some input on a solar heater installation. after doing some research, i gathered that roughly 75% coverage was ideal for the north east (i'm in new york, on long island). my pool has been between 76-79 degrees this summer. it has been a very cold summer, so many cold days and rain storms that i haven't bothered using the blanket. last summer i was averaging about 83-85 degrees just using the solar blanket religiously. this summer we hardly swam because the pool has been so cold, as we prefer 85+. ideally 87-90.

So i've been talking with two dealers, one is h2otsun, and one is a local reputable dealer/installer of heliocoil. I'm very handy DIY everything but I'm not really keen on doing a self install since i'm not a fan of going on the roof. That being said, apples to apples comparison for the two systems i've compared give me the following.

I cannot yet find a local installer for the h2otsun panels, so i will compare the parts alone for the heliocoil to the h2otsun, even though i have an installed price for the heliocoil.

panels/associated parts/solar controller (not including labor or long runs of PVC) for the heliocoil for 415sq feet of panel comes to 5,735. labor including trenching and long pipe runs is another 2100. 12y warranty on the heliocoils if installed professionally.

panels/associated parts/solar controller for the h2otsun for 600sq feet of panel (horizontal orientation fewer headers) came to 4,300.

My roof gets a ton of sun with no obstruction for pretty much the entire day. it is south facing with little wind. my pool is 20x40, and traditional measurements would imply a volume of roughly 30k gallons. However, after doing many chemical additions and seeing how my water responds to a given amount of any chemical, i have arrived at my pool being roughly 22,500 gal. it has a very shallow end, and the 8ft deep end has a lot of beveling with only a small portion actually beeing fully 8ft.

Obviously the heliocoils are more expensive and for fewer panels, but they are the only ones i can find a local installer to actually put in. my biggest concern is the difference in performance between 415 sq feet and 600sq feet. I only use the pool between may and september and would be using a blanket. in order to try and get 600ft of heliocoil, including labor, it quite frankly just gets out of hand budget wise. So the question is, is 415 square feet sufficient? or should i try to find someone who will install the other system in order to try and get more coverage for roughly the same installed price.

does anyone have any input with regards to the performance of their solar heater in the northeast based on a similar situation? should i just keep it simple and go with the local dealer/installer with the 415 feet or should i hold out on trying to find someone who will install the 600ft of h2otsun panels? Am i going crazy and going overkill expecting that i need 75% coverage for optimal performance?
 
Impossible for us to say how many sqft you need. Too many variables. Basically, the more panels, the more heat.

And you would likely want to be using the blanket to maintain the heat at night.
 
Look to see what options you might have for green energy credits.
Also, and this is a bit of left field thinking -- have you looked into PVs? As on electic solar panels?
If you have sun exposed roofs, it may be more beneficial to put PVs, which will offset gas heating expenses, and work year round.
 
More is definitely better. I would lean more toward 100% coverage. We have 240sf of panels and 720ish sf of pool and we needed to add a small heat pump to help out at times. Our pool is partially shaded only receiving full sun about 2 hours per day. Our panels also have partial shade. And we're in Texas.

I did most of my research with Solar Direct and I purchased and installed my panels from them. A solar controller is also essential to success along with a solar cover.
More discussion and pics in my pool thread, link in sig.
 
I will second the recommendation for a solar controller.

jeffblue said:
yes i would definitely use the blanket with the panels. i just gave up this summer as its been so cold regardless with or without a heater that it was just easier to leave it off since we weren't swimming anyway.
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I don't know why you would not use the solar blanket, especially with the cold nights we are having in the Northeast. All the heat that the pool may gain during the day, you will lose at night as the temps dip into the low 60's / high 50's. While it might not keep the water warm enough for you to swim, if we get a warm spell it would get you to swimming temp quicker if you can retain some of that heat.
 
I used to have about 50% coverage for my pool and the panels would heat up the pool pretty well for most warm days (+10F in one day) and I could easily go without a cover. But the problem without a cover is that the water temps will swing quite a bit from morning to night. I used to get a 6-8 degree swing which also means I lost 6-8F overnight.

With a cover, the swing is about half that. Plus now my panels (moved off the roof) are now only about 20% of the pool area and they still perform pretty well and keep the pool above 86F on most days. But now I need the cover a lot more and can only go without when air temps are above 90F.
 
Mario P said:
Look to see what options you might have for green energy credits.
Also, and this is a bit of left field thinking -- have you looked into PVs? As on electic solar panels?
If you have sun exposed roofs, it may be more beneficial to put PVs, which will offset gas heating expenses, and work year round.
Click to expand...

To be honest i haven't given it much thought. my electric bills aren't too bad, as my house is very well insulated and energy efficient (LED everything, Energy star appliances etc). my electricty bills in winter sometimes dip into under $100 per month and in summer with my hayward 2hp pump running 8hrs a day and using my CAC on only hot nights it crests into the 300's for only 2-3 months.

pooldv said:
More is definitely better. I would lean more toward 100% coverage. We have 240sf of panels and 720ish sf of pool and we needed to add a small heat pump to help out at times. Our pool is partially shaded only receiving full sun about 2 hours per day. Our panels also have partial shade. And we're in Texas.

I did most of my research with Solar Direct and I purchased and installed my panels from them. A solar controller is also essential to success along with a solar cover.
More discussion and pics in my pool thread, link in sig.
Click to expand...
Thanks for the suggestion. wow so it seems like the heliocol panels alone are about double the price through the dealer than those vortex panels are, and to be honest thats whats got me frustrated with this whole thing. the labor and everything else really isn't that bad, but so far the only place around here that i can find that will install solar is a heliocol dealer. it's killing me to see that i could basically have a 75-100% coverage system from h2otsun or solar direct for what these heliocol panels cost.
domct203 said:
I will second the recommendation for a solar controller.




I don't know why you would not use the solar blanket, especially with the cold nights we are having in the Northeast. All the heat that the pool may gain during the day, you will loose at night as the temps dip into the low 60's / high 50's. While it might not keep the water warm enough for you to swim, if we get a warm spell it would get you to swimming temp quicker if you can retain some of that heat.
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I will definitely be using a solar controller, i didn't mean to be vague about that in my original post. i just replaced my pump with an intelliflo 011018 so i'm excited to be able to have that interface with the solar controller. I normally would be using a blanket. last year i did religiously, this year it has been so cold anyway that even with the blanket (my heater is broken) my pool does not get up to a temperature i enjoy swimming at (85+). so to go out every morning and remove it and close it every night to not end up swimming because its still too cold is just a lot of effort with no real benefit. i have no problem using the blanket if it keeps my pool warm enough where i enjoy swimming, as it would if we had a warmer summer or if i had solar. once solar is installed i would gladly use the blanket again.

mas985 said:
I used to have about 50% coverage for my pool and the panels would heat up the pool pretty well for most warm days (+10F in one day) and I could easily go without a cover. But the problem without a cover is that the water temps will swing quite a bit from morning to night. I used to get a 6-8 degree swing which also means I lost 6-8F overnight.

With a cover, the swing is about half that. Plus now my panels (moved off the roof) are now only about 20% of the pool area and they still perform pretty well and keep the pool above 86F on most days. But now I need the cover a lot more and can only go without when air temps are above 90F.
Click to expand...

so 20% coverage got you 10 degrees with a cover? i'd be basically at 50% coverage, and i would be using a blanket and controller. That being said, my 20x40 pool is pretty low volume for how big the surface area is, so what i'm wondering is if i'll be ok with the 'lower' coverage (50%) vs my ideal 75%.
 
50% I got 10F in one day. With 20%, I can get about 6F rise with the cover. We have very high evaporation rates here because of the low humidity. It might not be so bad where you are. The more humid it is, the less heat that will be lost in general.
 
My suggestion is dump solar and go natural gas or propane. You got the pool to swim right? With all that money spent the enjoyment is totally lost if you are shivering both in and out of the water. Not to mention the extended season with a fossil based heater. I also like a very warm pool like 90 and we looked at heat pump and gas heat and ended up with gas. As far North as you are I think you are going to be sorely disappointed once the solar is in and running.
 

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I'm only commenting because I am in the "Northeast" also, but much further North... I'm in New Brunswick, Canada and we have had a cool summer here as well. New York would always get much much warmer weather than we do here, right on the Atlantic coast.

My experience is only with a home-made solar heater that has 800 linear ft of 1" black poly pipe in 4 parallel loops, not 800 square feet of panels. My pool is 18x42, and 30,000 gallons (lots of deep end). Very rough calculation, if the outside diameter of the pipe is 1.5", that would take 8 feet to get 1 square foot of area (if the "pipe were flat")... so it's roughly equivalent to 100 square feet... maybe as much as 200 square feet if you consider the round nature of the pipe and how the sun hits it. South facing garage roof.. pool and heater pipe are in the sun almost all day long.

I'm very pleased with this set up, using my Intelliflo pump only, I circulate all my water through the pipe on my roof, and controlled it manually with a valve (no solar controller yet)... but we were very good with turning it on for sunny days, off at suppertime, and off on cloudy days. Using a solar blanket also, very religiously whenever the pool was not in use.

My results... the pool was generally in the mid to high 80's all of July and early August... it did reach 90 for a couple of days in late July.

Take that for what it's worth... hope it helps.
 
PoolGate said:
My suggestion is dump solar and go natural gas or propane. You got the pool to swim right? With all that money spent the enjoyment is totally lost if you are shivering both in and out of the water. Not to mention the extended season with a fossil based heater. I also like a very warm pool like 90 and we looked at heat pump and gas heat and ended up with gas. As far North as you are I think you are going to be sorely disappointed once the solar is in and running.
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from my understanding, you can expect +10-15 degrees from a properly sized solar setup with a south facing roof which should put me above 85 for the entire season and over 90 for parts of the season. isn't natural gas about 4 dollars per hour to run a heater? i feel like any time i ran the heater and didn't swim i would feel like i just burnt money for no reason.

duanebe said:
I'm only commenting because I am in the "Northeast" also, but much further North... I'm in New Brunswick, Canada and we have had a cool summer here as well. New York would always get much much warmer weather than we do here, right on the Atlantic coast.

My experience is only with a home-made solar heater that has 800 linear ft of 1" black poly pipe in 4 parallel loops, not 800 square feet of panels. My pool is 18x42, and 30,000 gallons (lots of deep end). Very rough calculation, if the outside diameter of the pipe is 1.5", that would take 8 feet to get 1 square foot of area (if the "pipe were flat")... so it's roughly equivalent to 100 square feet... maybe as much as 200 square feet if you consider the round nature of the pipe and how the sun hits it. South facing garage roof.. pool and heater pipe are in the sun almost all day long.

I'm very pleased with this set up, using my Intelliflo pump only, I circulate all my water through the pipe on my roof, and controlled it manually with a valve (no solar controller yet)... but we were very good with turning it on for sunny days, off at suppertime, and off on cloudy days. Using a solar blanket also, very religiously whenever the pool was not in use.

My results... the pool was generally in the mid to high 80's all of July and early August... it did reach 90 for a couple of days in late July.

Take that for what it's worth... hope it helps.
Click to expand...

Thank you for the input, that does help me. perhaps 50% is fine then.

mas985 said:
50% I got 10F in one day. With 20%, I can get about 6F rise with the cover. We have very high evaporation rates here because of the low humidity. It might not be so bad where you are. The more humid it is, the less heat that will be lost in general.
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thats not bad at all for the amount of coverage.
 
so i'm doing a little more digging, and on poolheatpumps.com you can get a techno solis 9 panel 4x12 kit totalling 432 sq feet including controller and everything else i'd need for installation (except for the long PVC Runs, trenching, and labor) for 3150 + 250 shipping, so 3300. the local installer/heliocol dealer is looking for 5900 for the same amount of square footage worth of heliocol panels. The person who i met with from the company was very nice and i had a nice time working with him, but this is an astronomical price difference. assuming i use his 2100 labor quote including trenching and long PVC runs, it seems like i can pay 4200 for a 576sq foot techno solis kit and be out the door for 6400, which is 1400 dollars less than i was quoted for 415 sq ft of heliocol panels.
 
jeffblue said:
from my understanding, you can expect +10-15 degrees from a properly sized solar setup with a south facing roof which should put me above 85 for the entire season and over 90 for parts of the season. isn't natural gas about 4 dollars per hour to run a heater? i feel like any time i ran the heater and didn't swim i would feel like i just burnt money for no reason.



Thank you for the input, that does help me. perhaps 50% is fine then.



thats not bad at all for the amount of coverage.
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I have heard it is more like 1-2 degrees per day. I did do a lot of research before settling on a gas heater. Solar and a heat pump were about the same. But again my point was it isn't about the money it is more about the experience. Swimming in cold water is no fun at all. Gas will extend your season for really as long as you want. There are people in MD that keep their pools open year round. Yes, cost is around $500/month in the cold months. But you at least could open it in early May and close in October which is my plan. Probably the best of both worlds is to have, well, both.

Now if you will in reality get a 10-15 degree rise that would change everything. I suggest you talk to someone in your area that has solar heat and a similar sized pool and see what they actually get.
 
Also FYI: When I was looking at solar, most companies advertised heat gains in terms of "solar plus cover". This is kinda misleading. I found that most people do not use the solar cover after struggling with it a few times. If you don't use the cover, anything you gain in the day will be lost plus more at night. The system seems awfully expensive for the gains you get. Do more research!
 
1-2 degrees per day, indeed that is pitiful and i would never consider paying much for anything with such poor performance. i'm curious as to where that figure would have been, because 10-15 degrees seems to be pretty average almost anywhere i look.

gas heaters definitely have their place. if you want your pool very warm very quickly they are amazing. if the weather hasn't been great for a few days and suddenly its nice one morning, fire it up, your pool is going to be warm very soon. also they are much better for really extending the season. if i already had a functional heater of any kind, i would just bite the bullet and use it despite energy costs, but i'm basically starting from square one now and i like the idea of 10-15 degrees with 0 cost, but totally agree with you that some small increase of like 2 degrees is certainly not worth it.
 
http://www.jacuzzi-spa-covers.co.za/images/sunwise_pool_blankets.jpg?79
PoolGate said:
Also FYI: When I was looking at solar, most companies advertised heat gains in terms of "solar plus cover". This is kinda misleading. I found that most people do not use the solar cover after struggling with it a few times. If you don't use the cover, anything you gain in the day will be lost plus more at night. The system seems awfully expensive for the gains you get. Do more research!
Click to expand...

i think you might be co-mingling two different products. solar covers and solar heaters. 'solar covers' don't really have anything to do with solar (in fact their primary use is at night), and are a pretty misleading term. they are more or less a giant sheet of bubble wrap that prevents evaporation, which is the main cause of heat loss. they don't really help you increase your temperature, but rather prevent temperature loss overnight. the less heat you lose at night the higher you start the next day. they are very beneficial though because heat loss can be 5-10 degrees at night and thats 5-10 degrees less your heater, no matter what kind it is (gas/elec/solar) has to work to recover that heat. solar blankets shouldn't cost more than 200 dollars.

a solar pool heater is actually a 'panel' of strips of black thin piping that is placed on the roof (or sometimes on the ground in some setups) that essentially works by having water pumped up to the roof, which is generally 120-160 degrees in summer, absorbing heat from the roof, and then returning to the pool. These systems are the most expensive to install, but have no additional running costs aside from the pump. These are the units that get temperature increases of 10-15 degrees.

this is a solar pool heater
http://poolheaterworld.com/wp-content/uploads/2015/06/pool-solar-panels.jpeg

this is a solar blanket

http://www.jacuzzi-spa-covers.co.za/images/sunwise_pool_blankets.jpg?79
 
Sorry the link was broken: https://drive.google.com/uc?export=download&id=0Bw8ON_7zALxWUHdOanVnWURwcGc

Also, keep in mind that the numbers I gave you were total heat gain from the pool and the panels together. Plus it was more of a maximum under the correct conditions. If you do the back of the envelope calculations, a set of panels may add only 2-4 degrees per day on average but over time it accumulates so the total heat gain of long term solar over no solar is in the range of 10-20 degrees above nominal pool temperatures. It is an important distinction.
 

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