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: GLAZED 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% |
This 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.
 Back to AMECO home page
|
