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Thread: Boosting Solar Throughput

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    Boosting Solar Throughput

    Hi Everyone,

    In the past 2 summers, I havent really been satisfied with the way my solar heating system is working. It does bring the temperature up on warm, sunny days, but quickly loses that over night and takes all day to recover the heat.

    I know a solar cover would help dramatically, since its losing the heat over night, and I plan to do that.

    One other thing I was considering was adding a second pump. I currently have a 1.5 HP pump powering the filter, and have a spare 1 HP pump just laying around. The solar controller can turn on a second pump when it goes into heating mode, and I was thinking of just adding this second pump to the solar loop. The water coming out of the return when the solar is on is VERY hot, so I was thinking adding the additional pump would push more water through the heating panels and heat the water up faster (I read somewhere on here that there isnt enough water going through the system if it is more than a few degrees warmer than the water in the pool).

    Does that sound like a decent thing to try? It would only really cost me the extra PVC fittings to add the pump to the system.

    Thoughts?
    18' Round ABG (8000 gallon)
    Hayward X-Stream Cartridge Filter
    1.5hp Hayward PowerFlo Matrix Pump
    80 sq. ft. solar panels
    Goldline automated solar controller

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    JasonLion's Avatar
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    Re: Boosting Solar Throughput

    That would probably work, but there might be something simpler that you could do to get the same result. A 1.5 HP pump should be more than enough to get plenty of water flowing through the solar panels. Perhaps your diverter valve isn't sending enough water to the panels. It might be something as simple as adjusting the stop on the diverter valve so it sends more water to the panels.

    Do you have the system setup so that the current pump runs any time the solar controller is calling for heat? Adding a separate solar only pump makes the largest difference when there is some reason not to run the main pump the entire day.

    Another question is how many panels do you have? A 1 HP pump dedicated to the panels would be too much if you only have a couple of panels.

    Any additional information you can give up about your setup will help us give you better advice.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Mod Squad JohnT's Avatar
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    Re: Boosting Solar Throughput

    Your pump is already oversized for your setup, so I can't see how you could be having low flow. Does all of the pump output go through the solar? I can't run all of my 1HP pump's output through my panels
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: Boosting Solar Throughput

    Before I installed a solar cover, I was loosing about 15 degrees overnight (ambient 85 in the day, 60 at night). Now I loose about 1-2 degrees. Heck, I don't even need to heat the pool, the sun does it through the cover. Pool was 85 this morning when ambient was only 82 (clear sky, sun out).
    38K Gallons IG, Intelliflow VS-SVRS, 30GPM 24/7, 72sqft DE Filter, Spectralight UV, Jandy C1900 driving Liquid Chlorine and Acid (toys, I know..), Jandy LXi gas heater, Aquacal SQ175 Heatpump, Riverflow Competition swimmer, Jandy automation, Touch and iAqualink, Pebblesheen | The Build

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    Re: Boosting Solar Throughput

    Quote Originally Posted by shakenbake
    Before I installed a solar cover, I was loosing about 15 degrees overnight (ambient 85 in the day, 60 at night). Now I loose about 1-2 degrees. Heck, I don't even need to heat the pool, the sun does it through the cover. Pool was 85 this morning when ambient was only 82 (clear sky, sun out).
    Yikes! I'll bet you had a decent amount of wind or perhaps your air is very dry (very low relative humidity). Usually, evaporation wouldn't be that high to lose that much temperature overnight. I know in my own pool at similar day/night temperatures in the summer that having the cover off would lose about 6 degrees overnight while with a fairly thin mostly opaque electric automatic safety cover I lose around 3 degrees overnight. However, we generally have no wind at night (it's mostly in the afternoon). With a more insulating bubble-type cover, I estimate the loss would be more like 1-1/2 degrees by cutting down heat loss from conduction through the cover which is what you are seeing.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Re: Boosting Solar Throughput

    I know I could use more panels, only have 80 sq ft of them. Unfortunately I don't have any more accessible roof space without going all the way up to the top of the second story.

    The panels are a good 100 ft away from the pool.

    I'm surprised how low your temperature losses are. If I get the pool up to 85, it can drop into the high 60's overnight, a 15+degree drop. Our ambient temperatures are the same. It can be in the 80s during the day and in the 40s-50s at night.

    My pool is above ground, so maybe that's the difference?
    18' Round ABG (8000 gallon)
    Hayward X-Stream Cartridge Filter
    1.5hp Hayward PowerFlo Matrix Pump
    80 sq. ft. solar panels
    Goldline automated solar controller

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    Re: Boosting Solar Throughput

    Quote Originally Posted by chem geek
    Quote Originally Posted by shakenbake
    Before I installed a solar cover, I was loosing about 15 degrees overnight (ambient 85 in the day, 60 at night). Now I loose about 1-2 degrees. Heck, I don't even need to heat the pool, the sun does it through the cover. Pool was 85 this morning when ambient was only 82 (clear sky, sun out).
    Yikes! I'll bet you had a decent amount of wind or perhaps your air is very dry (very low relative humidity). Usually, evaporation wouldn't be that high to lose that much temperature overnight. I know in my own pool at similar day/night temperatures in the summer that having the cover off would lose about 6 degrees overnight while with a fairly thin mostly opaque electric automatic safety cover I lose around 3 degrees overnight. However, we generally have no wind at night (it's mostly in the afternoon). With a more insulating bubble-type cover, I estimate the loss would be more like 1-1/2 degrees by cutting down heat loss from conduction through the cover which is what you are seeing.
    It's been super windy here in austin for the last month or so.
    38K Gallons IG, Intelliflow VS-SVRS, 30GPM 24/7, 72sqft DE Filter, Spectralight UV, Jandy C1900 driving Liquid Chlorine and Acid (toys, I know..), Jandy LXi gas heater, Aquacal SQ175 Heatpump, Riverflow Competition swimmer, Jandy automation, Touch and iAqualink, Pebblesheen | The Build

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    Re: Boosting Solar Throughput

    Are you running your pump and circulating through the solar panels at night?If so,that would cool your pool down.
    11000 gal L shaped gunite pool with and aggragate plaster
    Pentair cartridge filtration with 1.5 hp pump
    only have 3 returns and one dedicated vacuum line
    manifold to pump is three valve

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    Re: Boosting Solar Throughput

    Nah, I at least know better than that

    I have an automated controller too, so it's not operating when the panels are cooler than the pool.
    18' Round ABG (8000 gallon)
    Hayward X-Stream Cartridge Filter
    1.5hp Hayward PowerFlo Matrix Pump
    80 sq. ft. solar panels
    Goldline automated solar controller

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    mas985's Avatar
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    Re: Boosting Solar Throughput

    Quote Originally Posted by Wolfmarsh
    I know I could use more panels, only have 80 sq ft of them. Unfortunately I don't have any more accessible roof space without going all the way up to the top of the second story.

    The panels are a good 100 ft away from the pool.

    I'm surprised how low your temperature losses are. If I get the pool up to 85, it can drop into the high 60's overnight, a 15+degree drop. Our ambient temperatures are the same. It can be in the 80s during the day and in the 40s-50s at night.

    My pool is above ground, so maybe that's the difference?
    100 ft runs could explain why your have such low flow rates through the panels. What size are the pipes and how high are the panels? Also, what is your filter pressure with the panels on vs off?


    Also, if you are seeing a 15 degree drop over night, that would imply that you have a 15 degree gain during the day but I don't think that is possible with 80 sq-ft of panels so something isn't adding up? How did you get the pool water to 85 in the first place?
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Boosting Solar Throughput

    1.5" all the way there. THey are about 9 feet off the ground at the low point, and 13 feet off at the high point.

    The place where the panels are is perfect, south facing. It gets sun all day long. Ill take some measurements once I get everything going again for the summer, but it does rise 10-15 degrees by days end. If i run the pump from 8am to 5pm, the panels stay on all day and the pool does get that warm (as long as ambient is also that warm). By the next morning, its back to the low temp.
    18' Round ABG (8000 gallon)
    Hayward X-Stream Cartridge Filter
    1.5hp Hayward PowerFlo Matrix Pump
    80 sq. ft. solar panels
    Goldline automated solar controller

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    leibin's Avatar
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    Re: Boosting Solar Throughput

    I'll have to chime in that a pool cover is going to be the cheapest and easiest way to maintain your temps. Here in AZ, where it is dry, I would experience around a 10 or more degree loss in pool temps right now without the cover on. With it on, I lose 2 degrees
    12k IG Pool / Spa - plaster
    Jandy ePump 2.0 & Hayward Power Flo II (for rock waterfall)
    Pentair CCP320 Cartridge Filter
    iAqualink RS controls & Aquapure PLC1400 SWG
    Pentair Minimax NT 400k btu heater & 6-4x12 Fafco Panels

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    Re: Boosting Solar Throughput

    I have a 20x40 inground pool and heat it mostly with 80sqft of solar mats that are on the ground near the pool. I always cover the pool when not in use which makes a huge difference. I have an intelliflow pump that I run at a very low flow rate during the day just to get flow through the panels. Since I have time of day electric pricing I only boost the pump output at night when power is cheap and don't let the water flow through the panels a night (obviously). This combination keeps my pool at 80-85 degrees most of the year and I only use my heatpump at the very start and very end of the season for maybe two weeks.
    20x40 IG vinyl, heatpump and solar and 3 siberian huskies, 10kw PV solar electric system. Nikon Photographer D800e dSLR.

  14. Back To Top    #14

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    Re: Boosting Solar Throughput

    Yeah, I think im gonna get the solar cover also.

    Since I have the extra pump laying around, I would only lose my time and a couple of bucks in fittings to add it to the system. Is the general consensus that this would be a waste of time?
    18' Round ABG (8000 gallon)
    Hayward X-Stream Cartridge Filter
    1.5hp Hayward PowerFlo Matrix Pump
    80 sq. ft. solar panels
    Goldline automated solar controller

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    Re: Boosting Solar Throughput

    The solar cover is more important than the solar heater!

    I think you would be wasting your time with the second pump and costing yourself a lot of money. Figure out what it costs to run a one HP pump - you will be surprised at how much it costs. Are you panels all piped in series? If so you might want to consider plumbing them in parallel, that will drop your pressure loss and increase your flow rate. Does all the flow go through the panels or only part of it? If part of it why not increase the flow through the panels?

    During the day I set my pump to run at about 200 to 300 watts and have the flow go through a pair of 2' by 20' panels in parallel, that is enough flow to have the water just slightly increase in temperature and get maximum heat extraction from them.
    20x40 IG vinyl, heatpump and solar and 3 siberian huskies, 10kw PV solar electric system. Nikon Photographer D800e dSLR.

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    mas985's Avatar
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    Re: Boosting Solar Throughput

    I agree, the pump is a waste of time and could possible cause more problems. With 80 sq-ft of panels, you only need about 8 GPM to reach maximum efficiency. You might actually try bypass some of the flow from the panels. What is your filter pressure with and without flow through the panels?
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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