Solar Roof Panels vs Heat Pump in CT/New England?

[m1rabel]

Hello and thank you for reading this post (first time posting, sorry if I make any mistakes!). We need some advice on heat pump vs solar panels to heat our 15'x30' oval above ground pool. We are in Connecticut and other than the month of July, the water is just too cool for anyone to comfortably swim in. Though we use a "clear" solar cover every night (and during the day when the pool is not used), the pool doesn't get enough direct sunlight. We have pretty much ruled out propane heaters based on expense though the idea of quick, on-demand heat is very appealing. Is there a "next best thing" that is cheaper to utilize? Our goal is to keep the water temperature swimmable for us (mid 80's ideally) from June through September (with occasional night swimming being even more ideal!). On average, the water temp. in June was low/mid 70's (didn't formally keep track though), the temperature peaks in July reaching around mid 80's most days then drops again to low/mid 70's in August and definitely September as air temps cool and the pool is in the shade more of the day. Water temp would likely need to be raised (and maintained) anywhere between 5-15 degrees in June, August and September (can a heat pump or solar panels even achieve the upper end of this?). Below are as many of our specifics as I could think to provide as well as a few primary concerns/questions. Any experienced advice you can offer to help us decide between a heat pump or roof mount solar panels would be very appreciated! (Next step would then be to get recommendations for brands!!).

Specifics:
* 15x30 oval above ground pool (10,600gallons) plumbed with 2" pvc (instead of the typical ABG flex piping) - a total of approximately 24' from pump/filter to pool, plus 3' up to skimmer/return.
* 2-speed Pentair Optiflo pump
* Pentair Clean & Clear 150 sf cartridge filter
* Roof where solar panels would be mounted is West facing but gets many hours of direct sunlight and is located directly behind the pool equipment. Would be about 10 1/2' up to roof edge.

Primary concerns and questions when comparing heat pump to solar roof panels:

1) most importantly, we want a heating option that does NOT require the pump to run on high if at all possible since we rely on the cost savings of running it on low. This is especially important if the heating method we choose requires a decent amount of running time to heat the water. I know I will need to figure out what my specific flow rate is when running my pump on low to be able to compare to the min/max gpm of the heating equipment. Is there a reasonably simple way for me to calculate this? Will the fact that we have 2" pvc plumbing to and from the pool (vs the standard smaller flex hose) impact the gpm?

2) like anyone, we want the best and quickest way to heat the pool (besides gas!). I know heat pump and solar panels each have their own pro's and cons and there is alot that impacts this - but in our specific application and region, is one really more effective than the other (cost-wise, quickness in heating the water, etc).

3) if we went solar panels, putting holes in our brand new roof is not real comforting a thought, but for those of you who have done this, is it truly a legit concern or if properly installed are leaks a non-issue?

I would like to have attached a photo showing the layout and roof area but am not sure how to do that.

Thank you again for any advice or personal experience from those with similar circumstances. I look forward to hearing back!

 

[tphaggerty]

I'm in Dutchess county NY and have had solar for 7 years. Heating an IG 20x40 with a northeast facing roof - proving that solar is definitely an option even in the NE and even without ideal layout. Of course, I have about 720 sf of panels!

With a smaller AG and west facing roof, you should be in great shape.

1) Get a solar controller that can kick your pump to high speed when running solar. Key to solar is LOTS of water to the panels. You don't really need that many panels, so you might be able to get by with a slower flow. But you won't get nearly as good heat increase.

2) Both heat pump and solar are basically slow ways to heat the pool. Both can be sized to increase the heat flow. In general, a heat pump is going to be quicker and can provide heat on days that solar might not be able to. On the other hand, solar is basically free after a year or two. I added a 2nd bank of panels to help our pool recover more quickly from rain & cloudy days - best to do it upfront!

3) The holes in my roof don't leak. Each was sealed with caulk as it went it (I have access to the attic and check on a regular basis.

The KEY to solar in our area is covering the pool at night. Evaporative cooling kills solar, you get a +5/-5 effect if you don't use a cover.

If you are close to NY, you can PM me, you are welcome to come by and see my setup.

 

[bk406]

I live in central massachusetts. I never considered solar since my house faces in the wrong direction. Also, when i would want to start to heat the pool in the morning for the afternoon, the sun wouldnt be high enough anyway to do much good.

I have a 120,000 BTU heat pump on a 14,000 IG. Works great at keeping the pool around 83-85 from memorial day thru mid august. Before and after that, not so much. I got a propane heater this spring and it was the best thing I ever bought for the pool. I know you said you didnt want propane, but to extend swim season into september, its the only way, IMO. It's just too cool at night for solar or a heat pump to work very well. Even with a solar cover, you lose too much heat at night forma heat pump or even solar to heat the water up given the shorter days.

This is just my experience, i'm sure others have different experiences. But IMO, solar and heat pumps just arent practicle to extend the swim season much beyond the end of august in NE.

 

[tphaggerty]

This is just my experience, i'm sure others have different experiences. But IMO, solar and heat pumps just arent practicle to extend the swim season much beyond the end of august in NE.

Depending on the weather, I swim until the end of October in water that is above 70. Right now, my pool is about 82, and that is after the 2 weeks of rain due to Irene and the tropical storm. It clearly depends on placement and amount of panels, but solar IS definitely an option for extending the season here in the NE. If I flipped my panels to the west facing streetside, I'm sure I could stay into the 80s into October. BTW - Canada has a great downloadable book on solar heating pools, something well north of 50% of the pool heating in Canada is solar....

I am the ONLY one in our neighborhood that keeps a pool open into October and I generally open in early May (sometimes in April, but that has proven to be not such a good idea), so the idea that solar is not viable for extending the season in the NE just isn't right.

 

[bk406]

This time of year, 82-83 is too cold for us. We like it up near 88 or so for september, and I cant get that with a heat pump, and i'm guessing solar too. It's all perspective on how warm you want the water.

The kind of heat you put on the pool really depends on what you want to spend, how late (or early) you want to swim, and how warm you like the water. If you can get pool water to 88 degrees in October with solar, maybe im missing the boat.

 

[tphaggerty]

Nope, 88 in October with solar probably isn't going to happen. Then again, I shudder to think what you are going to spend on propane to get that 88.

Seven years ago, when we built our pool, our neighbors said it cost them close to $3000 to heat their pool the first summer they had propane. After that, they only heated for guests. Since I can keep my pool close to 80 for basically free now, I'm good with solar (and I don't have to wait for guests) :-D !

 

[bk406]

This time of year I only use the gas to heat it up when I want it warm. Since april, I've spent about 600 bucks on propane. But then again I use my heat pump june thu august. I do use the gas to bump it in the summer. If the heat pump has it at 83 or so, I can put 4 degrees in it wth the gas in less than an hour. If I heated with propane the entire season, sure, it would get pretty expensive. If I had natural gas, I'd junk the heat pump and just use NG since here its really cheap.

 

[mokabb]

I installed solar on ground based racks last spring and it totally changed our pool usage. My family likes the pool in high 80s to swim in. Before solar, even with covers, we could sometimes get there for a week or two every summer. This summer, we were consistenly above 88 since the week before Memorial day until all the clouds and rain the past 2 weeks. Now we are back up to 87 today after two sunny days and I would predict hit 90 again tomorrow based on the forecast. Too bad my neighbors have such tall trees, because we start to lose the sun at 3 pm this time of year, so can only get about 6 hours of warming.

Best money we ever spent.

 

[m1rabel]

Great responses! thanks so much for all the useful information! I especially find any cost data extremely helpful - thanks for sharing and keep it coming! I'm wondering if it would make sense for us to first try a solar option, see how that goes for a season, then if necessary, add a propane heater for additional heating when and if needed? But then we're back to roof solar panels vs. heat pump. I know a heat pump has the advantage of heating even on cloudy days, but I "heard" they can take up to several days to get the pool temperature up to the desired level, and if I have to be running my pump on high that whole time, it would defeat the purpose of my 2-speed pump. But are solar panels any more effective at heating quicker and would I have the same "pump on high" issue? I'd really like to know if anyone has or knows of a brand of solar panels or heat pump that can work with a pump on low - I know this is hard to say without knowing what my GPM flow rate is while on low..... I need to find a way to figure that out....

Looking forward to more experiences and opinions (and any real life operating cost data for the different heating methods in this region!)

 

[bk406]

I know a heat pump has the advantage of heating even on cloudy days, but I "heard" they can take up to several days to get the pool temperature up to the desired level,

While thats true, a heat pump is meant to run consistently. At the beginning of the season, I ran mine up to 15 hours a day for 4-5 days to get from 40 degrees to 80 (I turned the pump off by 10 pm, there's just not enough ambient heat to justify it at night in NE). After that, I just set it at 83 and it ran when it needed to. They really aren't designed to heat up the water quickly. They are designed to maintain the desired temp ad run whne needed.
Generally, in May, mine runs between 6-12 hours to keep the temp at 82 or so. A lot of it depends on how cool the nights are and how much over night loss there was. In may in central mass, I lose around 5 degrees a night even with a solor cover. So to get it back to 82, it can run almost all day to get it there if the temps are in the mid 60's. If it hits mid 70's, it might take half a day. By mid june, it might only run 2-3 hours.
As far as cost, that varies on the electrical rates. My electric rates are around 15 cents a kW/hr. I figure my heat pump costs around 70 cents an hour to run, give or take. So for a 12 hour run to put in 5 degrees, it costs around $8. My gas costs $2.39 a gallon. I have a 400k heater that burns around 4 gallons per hour. I timed it this spring, and in mid May, I put 4-5 degrees in 14,000 gallons in about an hour. That works out to be about $9. So, if the HP runs all day, the gas is about as cheap. Obviously as the air temps warm the heat pump runs less and costs much less to run.
As far as solar, yea, its free after the cost of buying and install. I'm sure they work very well, a lot of people have them. We can just get pretty cloudy here in central mass in the afternoon in early and mid spring and again in the fall, so if the suns not out, not heat.
I guess if it were me, I would do the solar and see how it goes. If you find it not working for you in the early and late part of the season, I'd get the propane to supplement it. I wouldnt have the solar and heat pump together. Too much downside to both on either end of the swim season.