Swimming pools are hotting up. Exploit the sun’s natural energy and extend your swimming season with solar panels. Kathryn Alexander tells you how.
Living in sunny areas that get cold and snowy, and even where the sun shines long and hot, it makes perfect sense to use the sun’s energy. It’s free and it can extend your swimming season by as much as four months.
All you need to do is install solar panels and link them to your pool pump. This will enable you to heat the water in the pool to a comfortable temperature for swimming … at a time when it would normally be too cold to swim. It really is that easy.
Even though there is an obvious cost factor to install a solar heating system, once it has been installed, there are absolutely no running costs. Even when it’s cloudy, the sun’s energy continues to do its work.
“The basic principle is to run enough water through enough black stuff on the roof to get the pool warm.” Ann Kruyer
Various types of swimming pool solar heating systems are available, the most effective using inert black plastic polymers that cannot be corroded by pool chemicals or eroded by the water.
As a rule, solar heating units are incorporated into an existing filter circuit. The pool pump then operates the solar unit at the same time as it operates the filter system. The concept is simple: the pump circulates the water from the swimming pool, through the solar collectors and back to the pool. During this process, the water is heated naturally to between 24 and 34 degrees celsius (75 F and 93 F).
As Ann Kruyer, whose husband Dave designed his solar heating system explains: “The basic principle is to run enough water through enough black stuff on the roof to get the pool warm.”
This, she says, was a foolproof explanation she found on the internet during a research session to find out more about the ‘black stuff’ her husband uses to heat swimming pools – including their own. She is unapologetic about the fact that she doesn’t know how solar panels work. All Ann cares about is that her own pool water is heated gently to perfection by a solar panel using the generous free energy of the sun so that she can be comfortable and relaxed in the water.
For those of us who don’t have husbands capable of this kind of design capability, it does help to know that designs which incorporate individual tubes reduce wind load and allow the roof on which the panels are installed to breathe and dry out. It also helps to know how they work.
The panels Solar panels may be configured in different ways. The most common method is to install a continuous row of panels without any breaks. If there is a change in the level of the roof, the panels will need to be linked by additional pipes.
The size and area to be covered by solar panels will depend on a number of environmental and physical factors. These include the length of time the swimming season can reasonably be extended in your area; where exactly the pool is located; and how much shade and sunlight the pool is normally exposed to. The direction and angle at which the panels are to be mounted on your roof should also be taken into account.
For optimum efficiency, solar panels should face north. If this is not possible, additional panels may be required to run the system effectively. A roof with a very high pitch will require more panels as will a pool which is located in a very shady area of the garden. Any waterfalls, cascades and fountains in the pool will also effect the efficiency of the water heating process.
Most people employ contractors to install solar panels and these experts will determine how many panels are required for optimum performance. If you decide to go the DIY route you can find a solar heating expert that can calculate how many you will need, this could be calculated using a formula based on conditions in a specific area. This calculation method also assumes that you will be mounting the panels on a roof with a minimum pitch of 15 degrees.
Simply multiply the surface area of the pool by 40% and then divide this by the surface area of one panel.
Panels should be made of a durable, lightweight patented, polymer-based Polyolefin material which is resistant to corrosion, electrolysis, pool chemicals, ultra violet radiation, extreme temperature fluctuations and mineral build-up.
The collector construction is in the form of fine matt-black tubes and the pool water flows through these without the use of any type of heat exchanger.
As far back as 2003 swimming pool solar heating systems were available that are suitable for the DIY market. There is a one-panel system which can heat pools with a surface area of no more than 28 m2 (300 sq ft) to a desirable pool temperature.
Each panel is 6,1 m (20 ft) long, 1,3 m (4.25ft) wide and has an effective surface area of nearly 8 square meters (86 sq ft). A panel weighs about 18 kg (40 lbs) and when full, contains about 38 kg (84 lbs) of water.
Tested by various international research organizations including the Commission of Europeans Joint Research Centre, the DIY system has a heating power output of 52,1 KW derived from free solar energy.
Each DIY kit ideally should comprise of a solar panel, a vacuum breaker, an end cap, two adaptors, eight hold-down brackets and four lengths of black strapping. The size of your pool will determine how many solar panels will be required.
Installation is reasonably simple and any capable home handyman will be able to tackle the project successfully. Hundreds of these systems have already been fitted around the world.
T-fittings are installed in the flow line from the filter and a check valve is installed in the flow line to the solar system. A
12 mm (1/2 in) hole is pre-drilled into the flap of the check valve for draining purposes and gate valves are installed.
The flow line is connected to the bottom side of the solar panel one it has been fitted to the roof. The return line is then connected to the top of the panel and the vacuum breaker and plug are fitted on the adjacent end of the panel. It is important for solar panels to be adequately secured and for the vacuum breaker to be higher than the opposite 40 mm (1.57 in) adaptor on the hot water return to the swimming pool.
As a rule, any solar energy reflected from a collector tube strikes one or the other adjacent tube, and thus is also utilized. Unlike a flat surface collector, the grooved surface of these solar energy collectors leads to minimum energy loss through wind cooling.
Nevertheless, Brian advises the use of a solar pool blanket to save energy costs by preventing heat loss and reducing evaporation from the surface of the water.
“Pools lose heat in a variety of ways,” he says, “but evaporation is by far the greatest source of energy loss. Pool owners should be aware that they can lose up to 800 litres (200 gals) a day from an average 8 m x 4 m (8.7 yd x 4.3 yd) pool through evaporation. If a solar pool blanket is used diligently, these losses can be cut to a minimum, if not completely.”