Solar Pool Heating

• Pool covers are the most cost-effective measure to reduce heat loss, water evaporation and chemical use.
• The amount of collector area required is 50-100% of the square footage of your pool.  The amount varies depending on collector efficiency, site considerations (e.g. orientation, wind) and owner's preferences.
• Ideally the collectors should face south and be tilted between 20 and 32 degrees.
• Indoor pools, used year-round, require glazed, flat plate collectors, which should slope between 35 and 45 degrees.
• Roof-top vent pipes, etc. will interfere with the installation of some types of collectors.
• Due to poor orientation, or lack of rooftop space, pool collectors are sometimes "ground mounted" on a frame constructed near the pool.
• Most brands of pool collectors must drain completely when not in operation to prevent damage due to freezing conditions.
• All outside plumbing must drain back to the pool when the system is off.  Manual, seasonal drains are sometimes required.
• Paint all exposed PVC plumbing to protect it from damage due to solar energy.
• An additional booster pump may be required if your existing pump is undersized for the system.
• Manual operation, or a simple 24-hour timer may be substituted for expensive automatic controls.
• Always isolate the solar system when backflushing your filter.

Solar and Efficiency for Swimming Pools

Solar heating of swimming pools is one of the most economically practical uses of solar energy.  A solar system allows you to extend your swimming season, gives you more control over water temperatures and for many installations there is no increase in operating costs.

First Things First - Reducing Energy Losses

The most practical and economic step in extending your swimming season is the use of a pool cover.  As much as 70% of all the heat gained by a pool is lost through evaporation, and when you include losses from radiation and convection, the idea of heating a pool without a cover can be compared to heating a home with all the doors and windows open.  Although applying and removing a cover can be inconvenient, the cover not only helps extend your swimming season, it also keeps the pool cleaner and reduces chemical use.

A transparent cover also allows passive solar heat gain during the day.  Prices for a plastic cover range from $0.30 to $0.50 per square foot and last from two to five years.

How the Solar System Works

The plumbing of the solar system is plumbed into the existing filter system.  During the day while the filter is operating, the water is sent through the collectors before returning to the pool.  An automatic system adds a controller and sensors to operate a valve sending the water directly back to the pool or through the collectors to be heated.

In a more basic system, the homeowner sets the valve manually to run through the collectors while a timer turns the filter system on during those hours the collectors will receive direct sunshine.

System Sizing

There are a number of factors to consider in sizing the collector area and the first is the actual pool surface area.  Starting with a minimum area equal to 50% of the pool's square footage, system design is further affected by collector orientation, wind conditions, shading of the pool, local climate and length of swimming season desired.  100% coverage is not uncommon.

Orientation

Ideally the collectors should face true south and be tilted to latitude minus 10 to 15 degrees.  Increase collector area to 75% if collectors are laid flat.  Increase to 75% if collectors face west.  Other orientations are not recommended.

Although roof installations are most common, a frame can be constructed for "ground mount" for most solar systems when a roof installation is problematic because of inadequate space or aesthetic considerations.  In areas subject to winter freezing, the collectors and plumbing should be installed to allow all water to drain when the system is off.

Temperature

Pool systems heat a large amount of water each day and an efficient design returns the water to the pool after picking up two to five degrees Fahrenheit.

Collectors

Typical pool collectors are plastic panels which use large headers on top and bottom connected by a large number of small tubes.  The collectors are strapped to the roof at both ends and across the flat area of the collector.