I looking into heating our pool using solar energy. A bit of
background info first:
Location: Long Beach, California
Pool Size: 400-450 sq. Ft (L shaped)
The pool is in constant sunlight from sun up to late in the afternoon.
The pool is protected from wind loss on all four sides. Currently
(July), without any auxiliary heat source and with a bubble cover on
the pool, the water temperature is at 86 deg. F.
In the winter months, the pool temperatures dips to 55 deg. F. That's
a little too cool for a swim.
I've looked into commercially available solar systems, and they all
require significant roof or ground space. Unfortunately there isn't
enough roof or ground space to place a conventional system. The pool
and the garage occupy about 75% of the backyard (it's a small yard,
1940's tract housing) and the rest of the space is used for patio
space (it's not a big patio).
The only roof surface facing south, other than the front of the house
is the roof of the garage. The garage is a single story 20'x20'
structure with a hip roof. The hip roof does not have enough usable
surface area to fit the number of recommended panels.
While researching options, I was struck by the lack of sizing
difference between unglazed copper and rubber/plastic collectors. All
of the manufacturers I looked at using the same sizing guidelines,
regardless of the collector material (i.e. minimum of 50% of the
pool's surface area in collector area). That seems odd, since copper
is a much better heat conductor than plastic.
I'm thinking that a glazed solar collector the same size as an
unglazed solar collector, with all other conditions equal (flow rate,
..) would heat any equal volume of water to the same temperature! Am I
way out in left field?
Could I used fewer glazed copper collectors, say two and get the same
temperature rise as would four unglazed plastic/rubber collectors?
You don't have to install it on a roof. You could always create a
'roof' over the patio or use brackets to mount the panels on the
north side of the hip roof. You could even install the panels on
the ground somewhere.
The water is only being heated a few degrees so glazing and insulating
the collectors would add a lot of cost without really increasing their
performance. Remember, the goal is to produce a large volume of lukewarm
water and not a small volume of very hot water.