wrote in message
...
PipeDown wrote:

He is not a candidate for passive solar as he would like the option of
heating it in the winter if he wants (mild SF bay area winter)

NREL says 680 Btu/ft^2 of sun falls on the ground and 1050 falls on a
south
wall on a 48.7 F SF January day, so a pool with an R1 cover with 80% solar
transmission would collect 544 Btu/ft^2 and lose 24h(T-48.7)/R1, which
makes
T = 71.4 F. A reflective north wall might raise this to 90. And there's
this:
http://www.pacificgunite.com/solar%20pool%20heating.htm

Nick

That answer appeals to the engineer in me. Clearly under optimal conditions
Passive soalr is possible. Unfortunately weather is qute unreliable. A
couple days of rain followed by some cloudy days would cool the pool
significantly. I'll definately pass on the info