Would like feedback from NorCal folks with Solar Pool heaters

[dannieboiz]

I'm getting PV installed on my roof and the company i'm about to contract does Solar Pool heaters as their primary business. They're quoting $4k to install 500 Sqft system on my north facing roof. Another $500 if my system require a controller which I'll most likely need. My South and West roof is going to be used for my PV.

I think I spend about $125 a month in just heating the pool during the summer. I was told to expect an average of 80-85 degrees pool temp between May/June to about Sept.

I also have a gas heater. So we can use it in conjunction of the solar heater. We like our water around 90 degrees.

Wondering if it's worth it. for 4k it sounds pretty expensive.

 

[mas985]

I think I spend about $125 a month in just heating the pool during the summer.

That seems low to me. Have you done the actual calculations? Is that without solar? You shouldn't need any other heat with solar.

But 4k for solar is the going rate. You just have to compare it to what you would spend with a gas or electric heater.

 

[bignick]

I had a Heliocol system put in by Solaron back in 2009. I don't know how many square feet of panels I have, but my pool is only 450 sf and all of my panels are facing South. I paid $4300 out-the-door. I didn't need a controller since my controller was already compatible.

Being in Sacramento, it gets hotter than where you are, but I can easily maintain a temperature in the mid 80's during the summer. This year I am using a solar cover to reduce the evaporation and during those 2-3 weeks where the temps spike at 110, my pool got to the mid 90's. When I originally installed the pool, I went with a gas heater because I didn't like the look of the solar panels, but then I realized how inconvenient it was (I didn't want to have the gas heater on continuously). Solar is so much better. But the gas heater does come in handy like the time I was having a Memorial Day party and the ambient was only in the mid 70's, so I used the gas heater to get it to 85 degrees.

 

[bobby1017]

I had 300 sq ft of helicol panels installed on 8-2011, they are facing south at a 30 degree slope. The cost was $3500 but I already had the automation installed and the pad was stubbed for solar setup. Later I added another 25 sq ft to use all the space on the rack. I can expect the water to hold 80 deg by April 1st, during May thru Sept it will be at 86 deg by afternoon, I keep the thermostat at 85. Yesterday pm the temp was still 85 in the afternoon. This time of year all it takes is a string of 3 rainy / cold days to drop the temps to mid 70's, then it can never recover. My last swim last year was early November, but the temp was mid / low 70's.

 

[santacruzpool]

We are in the same place trying to decide on solar for our 450sq ft pool. We just swam yesterday and it was a cool but refreshing 74 degrees, today it is 72 due to overnight cooling.

We are stubbed out for solar to a corner just below our roof, and we have the automation and everything ready for solar, but I am not sure we need it. We opened our cover at night during our hottest days in August just to keep the pool under 90, as I never like it that hot.

Our quote is also $4000 for our system to be setup - but we are really not sure we will do it...

 

[Pool Clown]

That price is inline for the material and the labor but NOT THE LOCATION. You will not get the amount heat you should with your panels facing North. I don't think it is worth it for 80-85 + having to run the heater. That's really the reason to get solar in the first place, so you wont need to use the gas.

Curious, is this Poco Solar?

 

[chem geek]

I've got 466 square feet of solar pool water heating panel area, but not all are in the sun all the time (there's a tree that blocks two of them part of the year). If you want to have very warm water without needing any gas heat, then you'll definitely need a solar cover. We have an automatic electric safety cover that probably insulates half as well as a bubble-type cover. We keep our pool warm at 88ºF so really 86-87ºF in the morning to 89-90ºF by the end of the day. This post shows that with this scenario I don't need any gas at all in July/August but need some outside that range.

Basically, because you want your pool water very warm at 90ºF you really need to use a pool cover with solar, especially for the extended season. Note that with solar you won't have the water temperature be constant all day and night -- it will be coldest in the morning and hottest in the late afternoon. So if you want to swim in warmer water in the morning then you'd need to target even hotter for the late afternoon so that the temperature will be retained overnight. With my thinner cover I lose around 2-3ºF overnight depending on night temperatures in the summer and I'd lose about twice that amount (4-6ºF) if I didn't use a cover at all. With a bubble-type cover, you can expect to lose half of what I lose so perhaps 1-1.5ºF overnight during peak summer months. If I were using a bubble-type cover, I'd likely not need any gas from June through September.

Note that my panels are facing south-south-west. Your north-facing panels are NOT going to do very well during most months. The latitude of San Jose, CA is 37.3º so even at the summer solstice (end of June) the sun at peak noon (closer to 1 PM with DST) will be at 37.3-23.4 = 13.9º towards the South from the vertical. A standard roof pitch (except in snow areas where the minimum is usually 6/12 or 26.6º) is 4/12 so that's 18.4º. So a southern roof is quite efficient. A northern-facing roof of this type would have an angle relative to the sun peak of 13.9+18.4 = 32.3 and only be 85% efficient. This will really show up a lot during the extended season. I compare a southern exposure to a northern one below (assuming 4/12 roof pitch in San Jose, CA) for each solstice and equinox:

Date . Southern . Northern
6/21 .... 99.7% ...... 84.5%
9/23 .... 94.6% ...... 56.4%
12/22 .. 74.0% ...... 18.9%
3/20 .... 94.6% ...... 56.4%

The bottom line is that it's not too hard to get to the 80-85ºF range in the Bay Area, but getting a pool consistently into the 88-90ºF range takes more effort meaning a combination of solar water heating panels and an insulating cover, most especially if one wants to extend the season. Also, as noted above, a northern exposure means you are only going to get decent solar heating in June/July but not nearly as good beyond that.