Heating a swimming pool can be very expensive. Since we receive the most solar radiation during the long days of summer when we use our pools, solar pool heat is a great idea.
All pools should have a solar blanket on top when not in use. It will reduce the amount of chemicals needed, cut evaporation, and raise the pool temperature about 10°. It is especially important to have the cover on at night when outside temperatures drop.
There are special considerations with corrosion and salt water pools with solar thermal. So let us know if you have a saltwater pool.
Installing solar equipment for pool heat only is not currently eligible for most solar incentives. But if you install a domestic hot water system you can send excess summer heat to your pool. The additional cost to reach the pool, over a standard heat dump, is small and is not eligible for solar rebates but the majority of the system would be eligible if installed as part of the initial system.
There are 2 options for solar pool heat, stand alone systems, or using a domestic solar thermal system and a heat exchanger.
Solar Heat Options for Above-Ground Pools
- DIY project. Get 200 ft of black 2 inch pipe. Connect it to the pool filter outflow. Place the pipe in the sun. Use a timer so you allow water to flow only when the sun is on the pipe. There are also temperature sensor to automatically divert the flow.
- Install a stand alone solar pool heater. These run about $250-750. You can buy a simple system on-line, or we are happy to install a higher quality system for you. Basically these are black “plastic” panels that the water is routed through. Ideally they are mounted on the roof, out of the way. You can expect these systems to last up to 10 years.
- If you have a Solar Thermal system that provides your home's hot water or heating needs, you probably find you have excess heat in the summer. With the use of a heat exchanger you can direct this excess to heat your pool water. Depending on location and pipe distance, the extra cost is about $2,400. This option will give the best performance and durability. While pool heating does not qualify for federal tax credits, most of the cost of using your pool as the necessary heat dump for your domestic solar thermal hot water system can if it is installed as part of the initial system.
Solar Heating Options for In-Ground Pools
Generally speaking, an in-ground pool contains much more water than an above-ground pool and the surrounding soil provides better insulation. A in-ground pool can use any of the above options, but due to the increase amount of water, the system sizing will increase. If you have an in-ground pool we highly recommend you consider installing solar thermal for your domestic hot water needs and use your pool as a heat dump. While pool heating alone does not qualify for federal tax credits, most of the cost of using your pool as the necessary heat dump for your solar thermal domestic hot water system can if it is installed as part of the initial system.
For commercial applications, such as camps or summer-only hotels we recommend flat plate solar thermal collectors. They give excellent spring/fall output and are less expensive than evacuated tubes. They can provide hot water for shower facilities as well as the pool.
Solar Heating Options for Hot Tubs
Hot tubs have small quantities of water, but the temperature needs to be high. The inexpensive solar heaters will not create the temperatures necessary. You can use your hot tub as a heat dump (see above) for your solar thermal domestic hot water/heating system. Due to the tub's small size, it is likely that you will still need an additional heat dump to prevent overheating. Since hot tubs require careful temperature control, a backup system will still need to be in place. We find the majority of the time connecting to a free standing hot tub is not worth the additional expense.
Integrating solar hot water with pool heating
Pool water cannot mix with domestic hot water. So a heat exchanger box is used. Pool water can be corrosive so it is necessary to use a heat exchanger that is designed for pool application. If there is any possibility that the pool will not be able to absorb all excess heat from the collectors, an additional heat dump should be installed. This may be the case when the pool is open for only a short period during the summer, especially with large solar thermal systems designed to do home heating.