How A Solar Pool Cover Works

A solar pool cover acts to both reduce evaporation, trap heat in the pool water and keep leaves and other debris out of the pool. All this adds up to substantially less work more pleasure for you from your pool. The environment also benefits from reduced water and chemical usage.

Sources of Heat Loss

Heat is lost from your pool in three ways: through evaporation, radiating heat to the atmosphere and by loss to the ground for in-ground pools or through the walls for above ground pools. While there is little that can be done about the last of these heat losses, the others can be minimized through the use of a solar pool cover.

Approximately 60% of the heat lost by a pool is through evaporation. A pool cover virtually eliminates evaporation by not allowing the water particles to leave the surface of the water body. This forces them to stay in the pool, where the energy they have obtained contributes to the general temperature of the water. In a large pool in a temperate climate, water evaporation can account for up to 60,000 litres of water lost annually, so adding a pool cover is not only a sensible measure economically, but environmentally as well.

Radiant Heat Loss

This is very similar to the process of evaporation except that the water molecule loses energy to the atmosphere rather than by escaping the water body. This energy is given off in the form of infra red radiation. This accounts for roughly 30% of the heat loss from your pool.

A solar pool cover minimizes this loss by adding a layer of material between the water and the atmosphere that can catch the lost energy. This means that the pool cover will heat up, but a well designed cover will not allow that energy to be lost from the topmost layer of the cover to the atmosphere. This is due to the insulating nature of plastics and air, which pool covers are made from.

Heat Loss From The Pool Walls And Floor

The remaining 10% of heat lost is through the walls ans floor of the pool. This is probably slightly higher than 10% for above ground pools as the walls are exposed to the air. There is nothing that can be done about this source of heat loss for pools that have already been installed, save for wrapping an above ground pool in insulating material which would probably produce an unsightly result. For new pool installations it is worth taking into account the insulating properties of the base and sides of the pool. A well informed dealer or manufacturer should be able to explain how to minimize heat loss through selection of the most appropriate construction materials.

Heat Gain: Capturing Sunlight

In addition to reducing heat loss, an effective solar pool cover will trap sunlight to increase the temperature of the water. The effectiveness of different pool blankets will depend on the materials they are made from, particularly the surface that is exposed to the sun. Clear covers let the maximum amount of light through to the water which gives a higher water temperature.

Darker colour covers absorb more energy in the cover itself which effectively prevents that heat from being absorbed by the water. This makes the surface of the cover hotter than the surrounding air and the cover will then radiate that heat in all directions. Some of this heat will go into the water, but some will also be lost to the air.

Darker pool covers are also prone to damage from the sun for this same reason. In short, the clearer the pool cover, the more effective it will be at trapping heat.

Look For Quality

A quality solar pool cover will come with a significant warranty against decay from exposure to the sun. While a high quality cover will be more expensive initially, the the long term saving of not needing to replace it must be taken into account.

Quality pool covers will come with a clearly stated and comprehensive warranty. Any vendor that does not offer a warranty on the item should be avoided.

A Roller May Be Needed

The more expensive pool covers tend to be thicker and therefore heavier, so depending on the size of the pool to be covered a roller for retracting the cover may be necessary. The cost of this needs to be considered, as do quality and warranty issues associated with the materials and workmanship of the roller.