Solar Pool Heating Information
General Description of Solar Pool Heating
When solar panels are used to heat swimming pools or spas, two basic types of panels are usually considered: GLAZ
ED or UNGLAZED. A solar absorber will typically be manufactured of rubber, plastic or metal (i.e. copper). An unglazed panel will consist of an absorber plate only. Glazing is a transparent plastic or glass cover which is applied over the top of an absorber to reduce convective and radiative heat loss. Usually a glazed collector is insulated to enhance its ability to operate in cold air conditions.
Heating pool water in Southern California is normally accomplished with unglazed and uninsulated solar collectors, which can provide moderate pool temperatures (76º F to 90º F) for a maximum "swimming season" of April to October. Unglazed collectors are influenced by air temperatures and are not expected to heat the pool to comfortable temperatures during the intervening months of November to March. A pool blanket will help retain the heat that is developed, and when used in combination with a solar system can extend the swimming season into the winter months.
An alternative to heating pool water for a nominal swimming season is to employ glazed and insulated solar collectors, which can operate on cold days when the sun is shining. A properly installed glazed pool system will not only provide a maximum swimming season but will contribute significant energy to the off-season heating requirement. As a result, many large commercial swimming pools, which are heated for the entire year, will rely upon glazed solar panels. In addition to the improved performance, glazed solar panels are more aesthetically pleasing and look like skylights. A solar system for heating spa water or pools for therapeutic use should employ glazed collectors since temperature requirements are higher.
Flow through the solar collectors should occur only during the daylight. Since the panels normally receive water from the existing pool pump, the use of a solar system incurs no electrical penalty. For this reason, it is important to size the system in order to gather enough energy during the pump's normal operating schedule. With the surface area of the swimming pool as a baseline, the following chart can be used to estimate the surface area of a solar system to provide the following seasons:
Percentage of Pool Area
Tilt Between 15º and 30º
| EAST (Direction Panels Would Face) | ||
| Desired Season | Inland | Coastal |
| June - September | 68% | 78% |
| May - October | 80% | 88% |
| April - November | 100% | 120% |
| SOUTH (Direction Panels Would Face) | ||
| June - September | 50% | 60% |
| May - October | 65% | 75% |
| April - November | 82% | 94% |
| WEST (Direction Panels Would Face) | ||
| June - September | 60% | 74% |
| May - October | 75% | 85% |
| April - November | 94% | 106% |
his chart has been developed over the years by trial and error. Collector performances vary and every pool is different. Thus the values produced by this chart can be considered to be estimates only. Systems installed on flat roofs are usually sized at 100% of the pool area.
Note: If the pool is in the shade between 10:00 AM and 3:00 PM, add equal square footage to offset.
Example: Swimming pool area is 450 square feet, inland area, south facing roof, 20% pool in shade, April to November Season: (450) x 82%= 369 + (450) x 20% = 90; total solar system area should equal 369 + 90 = 459 square feet.
