How to Use Solar Energy to Heat a Pool

Two Methods:Harnessing Solar Energy on a BudgetEmploying Advanced Solar Heating Systems

Heating a pool can be a very costly undertaking that could be potentially damaging to the environment. As pools are mainly used during the summer heat or in locations that are hot year round, sunlight may be a smart option to keep the water at a comfortable temperature. The success of heating your pool with sunlight will vary depending on how much sun you get, the size of your pool, and the method that you choose to heat your water.

Method 1
Harnessing Solar Energy on a Budget

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    Add more length to your hose when you are filling your pool. The length of the hose contributes to the temperature of the water within it. While fifty feet of hose is generally sufficient, more length means that the water in the hose will have more time to warm up and the added surface area gives off more heat as well.[1]
    • Use a dark colored hose because the darker the color, the more solar energy is absorbed.[2]
    • A black rubber hose is ideal and is relatively inexpensive. Alternately, use black garden irrigation pipe because it is thin-walled to allow quick heat transfer. While it is inexpensive, it will also kink easily. Both are readily found in most home supply stores.
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    Angle your hose towards the sun and try to expose as much of it to the sun. When filling your pool, point the hose directly towards the sun or leave space between your hose and any surface so it does not cast a shadow onto itself. This allows a greater angle for the moving sun to strike the hose and heat the water within.
    • Mount your hose on a board that can be angled towards the sun for more exposure.
    • In some cases you may want to mount the hose on a board and attach it to a sun-facing roof. This is not recommended unless you have a suitable low roof, such a shed, or are skilled at working at roof height.
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    Fill the pool slowly. Use a thinner stream of water when filling your pool because it will heat more quickly. Try keeping the stream around half an inch in diameter to allow it to take in heat while still filling the pool at a decent rate. Use a hose that is ⅝ or ¾ inch to slowly fill the pool.[3]
    • Most in-ground pools will have a hose bib that may be used to drain water from the pool. allowing the pool to fill slower will allow the water to spend more time collecting heat as it moves from the pipes, to the hose, to the pool.
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    Set many pipes in parallel when using an above ground pool to increase heat gain. Water will heat up any time they flow within exposed pipes that are above the ground. Be cautious because the sun can heat exposed pipes to a temperature dangerous to the touch.
    • If your system is working correctly, your pipes should be cool to the touch, as this means the solar heat is being harvested and transferred to the water, instead of being released to your hand.
    • Above-ground pools will lose more heat overnight, when overnight temperatures drop below the pool water temperature.
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    Prevent energy from being lost. The biggest loss of energy within water is from the surface due to evaporation. This can be prevented by buying a pool cover. A pool cover that is translucent will allow the water to absorb solar energy during the day without losing it throughout the night.[4]
    • When a cover is on for 12 hours of the day, up to a 5 degree fahrenheit difference from air temperature can be seen.[5]
    • Pool covers not only reduce cleaning time but also the amount of chemicals needed to clean the water.[6] This will prevent you from needing to drain your pool and thus, start collecting energy over again.
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    Use a solar blanket. Solar blankets are pool covers that look like bubble wrap but are designed specifically to soak in the maximum amount of solar energy, and transfer it to your pool.[7] They are noted to produce a 5-15 degree increase in water temperature. [8] Simply cover your pool by placing the bubble side down and heat cannot escape, even or cold and rainy days.
    • Solar blankets are an inexpensive option as they cost approximately $75 and will last up to five years.
    • Solar blankets also keep debris off of your pool and are great to use at night when most of the heat that was collected from the daylight is lost.

Method 2
Employing Advanced Solar Heating Systems

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    Mount an unglazed solar collector on the roof of your home. These are made of heavy duty rubber and coated with a UV light inhibitor to extend the life of your panels.[9] Solar collectors work by pumping water through the solar collectors which are then warmed by the sun.
    • Unglazed solar collectors have inexpensive parts and simple designs making them significantly less expensive than glazed solar collectors. Unglazed solar collectors are approximately $3000 and last up to 7 years.
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    Mount glazed solar collectors around your home. These are a more expensive alternative to unglazed solar collectors but are more effective in producing heat. Glazed solar collectors are made from copper tubing sandwiched between an aluminum plate and iron-tempered glass.[10]
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    Maintain your filter to ensure that it is effectively cleaning debris from your pool. Pool water is pumped through both the filter and the solar collectors so keeping them properly maintained ensures that they are performing at their peak and no heat is lost.[11]
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    Maintain your pump. Usually a pump circulates the heated water from the solar collectors back into your pool. If your pump is working poorly, you aren’t getting the most out of your solar collectors.[12]
    • Be careful not to let water drain from the hosepipe so that the pump is running "dry" as this will damage the pump. Once water is flowing be sure to keep the end of the hose in the pool to prevent it from running dry.
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    Employ solar rings. These clear, inflatable disks will heat your pool effectively, as one ring transfers up to 21,000 BTU a day.[13]
    • The advantage to solar rings is that they are easily removed and disassembled for winter storage.[14]
    • Buy enough rings to cover approximately 80% of your pool. A ring is generally 59 inches in diameter.
    • Rings will generally last 5 years and cost up to twenty dollars each but, considering that they don’t use any electricity, this is a moderate cost.
    • To set up the rings, use 4-5 breaths to fill the outer ring with air. Next, inflate the inner rings using the same method. Remember to scrunch the ring up with your hand to distribute the air. It’s unnecessary to fill the rings all the way as they will be just as effective while mostly filled.[15]
    • Rings can be left on your pool while the cover is being used.


  • Solar collectors will work on cloudy days and overcast skies as they collect UV and thermal energy from the sun, which cuts through clouds.[16]
  • Make sure the water is over 60 °F (16 °C) to avoid lowering your body temperature and reduce the risk of hypothermia.


  • Do not use spaflex, tigerflex or any form of flexible PVC to run the solar plumbing as these pipes deteriorate quickly when exposed to direct sunlight and UV.
  • Do not expect major increases in temperature - this is unlikely to help make the pool usable in the Winter but may extend the swimming season.
  • If you want to use solar energy for warming water for other purposes, note that most garden hoses are not suitable for use with drinking water. You will need to set up a 'heat exchange' system or use food-quality hoses.

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Categories: Solar Energy | Swimming Pools Spas and Hot Tubs