Peter, it works! Today (May 11th 2019) first time that we had 38°C in the jacuzzi and only due to solar pool heating! Great job! Thanks a lot!
Are you a proud owner of a pool in Spain and want to use it a for a longer period of time during the year, or simply want to have the pool water a bit warmer during summertime?
Then get yourself a pool heating system with the sun as the only source of energy and that will do its job with absolute reliability.
There are different technologies to heat water. First the so-called conventional technologies, using fossil energy or electricity and then those, using the sun: an environmental neutral source of energy and free of charge.
According to the actual spanish legislation, it is prohibited to use fossil energies, such as oil or gas or electricity for outdoor pools. You can read in the spanish building regulations (RITE BOE Num. 89/13.04.2013; page 17): „Outdoor pools can only be heated by renewable energies or using industrial heat ...“ (free translation)
However, air heat pumps are most common in Spain and are using the energy of the air for heating the pool water. The ratio between the energy gained and invested for running a heat pump, is called COP (Coefficient Of Productivity). The COP of air heat pumps is a function of the outside temperature and varies between 1,5 and 6. Manufactures of air heat pumps determine these COPs under standard conditions (e.g. 20°C outside temperature). In winter though, when outside temperatures are significantly lower then 20°C, the COPs unfortunately drop to values of 1,5 or even 1, meaning that the heat pump is practically producing only as much as energy as it has consumed.
Please note that heat pumps have the great advantage that they can provide heat to the pool, regardless the wheather conditions and how long the sun shines. The electricity consumption and the associated costs to heat the pool certainly represent the negative aspect of heat pumps.
Heating the pool in this way, may represent a quite costly solution. Using the night tariff of some electricity providers does not really solve the problem. The night tariff is certainly less expensive, however, the COP during night time is - because of the lower outside air temperatures - a lot lower as during day time, and thus you will have gained nothing.
Heating the pool with the sun, means that you practically neither have any running costs nor environmental contamination. The „uncomfortable“ aspect logically is that you need the sun for it. On a cloudy or cold day, a solar pool heating does not work perfectly. However, this is getting compensated by the fact that outdoor pools are generally not used during winter time or during days of bad weather. Nevertheless, with abundant sunshine during spring and autumn, solar pool heating is very well possible and really makes sense.
Each solar plant has a solar collector, which is getting heated by the sun. Thanks to this energy gained, you can heat the pool by either pumping the water directly through the solar panel (open system) or by using a heat exchanger (closed system). Whenever the temperature in the solar collector is a bit higher then the pool water, a pump is getting activated to push the heat into the pool.
In case of open systems the pool water flows directly through the solar collector - ideally using the filter pump! In relation to the size (in m²) of the open systems and the wheather conditions, you can obtain daily rises of the pool temperature of some 2 to 6°C.
With other words, the running costs of a ROOS® solar plant for pool heating are zero!