Swimming pool solar water heater system is one of the simplest and the most economical applications for free sun heat usage that does not require high initial investment, but it provides faster payback than most of other renewable systems.
Solar pool water heater system is the right choice if planning to use and heat the swimming pool in and off the season (extended swim season), where free sun energy is used to increase the temperature in the pool.
Keep in mind that unheated pool will have the temperature a little above the outdoor temperature (if located in the southern warmer regions).
Swimming pool solar water heater has to be properly sized and provide desired temperature. If not than the backup boiler has to be used.
Picture is courtesy of energysavers.gov
The most popular pool solar heating system is where the solar panel is made of black PP plastic, rigid or with the individual pipes and usually roof mounted. Water is inside the collectors only when it circulates through. This is why this system is called the drainback system, as seen in domestic solar water heating. This is helpful in the winter time so chances of water freezing inside the solar panel and pipes are significantly reduced.
The main advantages of the solar water heater for pools are the required temperature, which is lower than for domestic hot water production, and the absence of the separate storage tank.
Here are other reasons why to buy and install swimming pool solar water heater system:
Low initial cost.
Low annual operating costs.
Easy to install.
Solar pool heating systems are efficient and durable.
Maintenance free systems.
The main components of the swimming pool solar water heater system are:
Collectors or panels
Controllers (i.e. to compare incoming and outgoing water temperature).
Pool solar collector is probably the most important part in the heating system. Solar collectors are usually roof mounted and designed to heat large amounts of water to relatively low temperatures, which is between 80 and 90 F. This is achievable due to the material used, which is polypropylene. This cheap material allows pool solar water heater to be affordable over expensive version with copper tubes. Another reason to achieve "low" water pool temperature is its unglazed setup.
The problem with the unglazed or uninsulated collectors is the collector incapability to produce any heat during the winter time.
Due to the limited operating temperature, which is usually between 220 F and 240 F, polypropylene solar collectors cannot be installed inside the glazed box to increase the efficiency as the manufacturer will void the warranty.
Standard sizes for pool collectors are 4 feet wide and 8, 10 and 12 feet in length. Top and bottom tubes are called header tubes with the size of 1,5" or 2" connected with the risers, 1/4" in diameter. Solar panel is through the headers connected to the PVC pipes by the rubber couplings and hose metal clamps.
Pool's filtration pump is used to transfer the pool water to the solar panels where it is heated by the sun radiation and then returned to the pool. Before the water goes to the solar collector, it has to go first through the filter. On its way back to the pool, it will usually go through the backup heater and the chlorinator if they are used.
As this heating system is drainback system, when pump is turned off, water from the collectors drains down to the pool.
If you are handy at plumbing and electrical wiring, it is very easy to build and/or install swimming pool solar water heater. Simply buy the solar water heater kit and the rest is like a puzzle. Use the glue and hose clamps to put the system together.
How will you determine the size of the solar panel... total length of the panel should cover 50% of the pool's surface area (for example if the pool covers 600 sq.ft collector should be at least 300 sq. ft). This rough calculation assumes the southern warmer regions (Florida, Texas), if the panel is properly oriented and if there are no shaded parts in the pool. Otherwise you have to increase the exposed area of the solar panel.
When building a solar collector recommendation is to use the above PP tubes, black flexible rubber mat, arrays of black plastic pipe or tube-on-sheet panels made of copper or aluminum. These collectors are called flat-plate collectors that feature large diameter headers and many small tubes between them.
Install the solar collectors so they will face south and tilted at an angle equal to the latitude of the pool's location minus 15 degrees.
To buy a DIY solar water heater kit, size of 300-400 sq. ft., expect to pay from $1500 to $2500 that depends on complexity of your system and the pool size. But if you want someone else to install it for you, it will cost you double. Warranty from the manufacturer is usually 10-15 years, which depends on the quality of the UV screening materials (inhibitors) and predicted payback period is 2-7 years.
Most of the heat loss, which is over 70%, from a swimming pool is caused by evaporation of water from the surface. Warm water evaporates more rapidly than cool. To reduce the heat loss during the evaporation, buy a good quality pool cover and save.
The heat loss is directly proportionate to wind velocities, pool temperature, humidity and air temperature. The most important factor is to have the swimming pool installed in a sunny spot as more than 75% of the solar energy is absorbed by the pool water.
Keep in mind to properly size your swimming pool solar water heater so the heating system can have the minimum of the heat loss and maximum heat gain. Take into account the location of the swimming pool, shades, winds, and is the panel oriented to the south.
Andy made this DIY solar pool heater from 100 ft coils of half inch plastic pipe for the pool size 30 feet x 12 feet x 4 feet average depth and 11,000 gallons. Solar panels are installed on the roof and due to the roof layout are facing east. This panel was built 5 years ago and the cost to build was around $300 for tubing and PVC but the framing materials came from scrap... more
Another simple homemade pool solar water heater made by Fraser located somewhere in Spain. He built the heater for 70 Euros for the pool size of 60 m3 and 1 m3 insulated hot tub while keeping the temperature of 35 C year round... more
How to build a solar pool water heater from instructables.