subject: Solar Power Pool Heaters: How They Work [print this page] Solar power is a rapidly evolving technology and you can harness its latest advancements for heating your pool. Solar pool heating is cheap, reliable and cost effective in any setting. If you're interested in just how the energy gets from the warmth of the sun to the warmth of your pool, here's a rundown of the process.
Pool Solar Heating - What is it and how does it work
Solar heating recirculates your pool water through a system of mats or panels on a roof. Each panel normally consists of smaller fine tubes which heat the water as it passes through. Despite claims, performance is normally less a factor of brand than a factor of system set-up. The performance of a system depends on the amount of tubing on the roof, how well it faces the sun (orientation) and the general weather conditions (including hours of sunlight and wind).
Most systems work by 'cutting into' the plumbing near the filtration system and diverting the recirculating pool water to a roof solar collector. The water is heated by passing through the solar collector, then directed back from the roof to the plumbing near the filter. The piping used to and from the roof from your filter is normally PVC plumbing pipes and fitting (i.e. the same type as your filtration system uses). The plumbing will also need a few 'gate valves' (or taps) to control diversion of water-flow from the normal path to the solar collector instead.
How much solar collector space do I require on the roof?
To effectively heat with solar, the general rule of thumb is that you require a solar collector that is equivalent to between 75% and 100% of the water surface area. For example, if the pool is 8m by 4m, the surface area is 8 x 4 = 32 square meters. A '75% system' would require 24 square meters of roof collector. A more powerful and effective '100%' system would require 32 square meters of roof collector.
For best performance, your roof and solar heating panels should face north. A north facing roof gets sun all day. If you have to use an east or west facing roof, don't be too concerned as this can still work quite well. You might however add an extra panel or two to make up for the slight performance loss.
Options to consider:
A Booster Pump - Pumping the water to and from the solar collector on the roof can take a lot of work. How much work depends on the distance between the filtration system and the solar collector. If the collector is some distance for the roof in question, you will probably need an additional pump (e.g. 0.5 to 0.75hp). This pump operates concurrently with the main pool pump, taking the strain off your filtration system.
Automatic Controller - Automatic controllers decide when and when not to run the solar pool heater system. One basic function is that of a thermostat, stopping the system when your desired temperature is reached.
A more important function is that of deciding when to run the system.
For example:
Let's say your pool's water temperature is 21 degrees, while your target temperature is 23 degrees.
While you might be inclined to keep running the system, it might be advisable to stop the system running further.
The classic example would be a sunny morning followed by a cloudy afternoon. While running the system in the morning makes sense, continuing to run during the afternoon may actually chill the water as it passes through the collector (robbing you of valuable pool water heat).
Finally - Cover Your Pool
Remember- While your solar heating system sends heat to the pool, the pool is also losing heat.
Most heat loss occurs as simple evaporation at the pool surface. This can have a dramatic chilling effect on the pool water. For your pool temperature to rise, you must add heat to the pool faster than it is being lost.
One way to improve the heating capability of your system is to have a larger collector. A smarter and more economical way to achieve the same goal is to use a pool cover to reduce the rate of heat loss.
Example:
A covered pool with a 75% collector area may outperform a 100% sized collector where the pool is uncovered. Basically, adding a pool cover is like 'turbo charging' your solar heater's performance.
