Hi. I run a solar business and we are doing a large installation in Phoenix and there is not much room for water storage and I hope to use insulated ground storage. I am considering large excavations with perhaps 1/2" inch slinky loops of pex (temperatures to 170 deg F) and I am looking for referrences to help me size the tubing, total distances. I am looking at probably 200-300k of mud for storage, insulated probably with 6" EPS all the way around. LIner will be EPDM. The amount of heat storage could easily be 5-10 million BTU's. Eric Friedland Swiss-Solar.net

If I'm not too batty due to the hour, Eric, I'm not sure you mentioned how many BTUH's you hoped to extract from the mud.
J

You might want to look at the Drakes Landing Solar Community for some inspiration on interseasonal heat storage in the ground: http://dlsc.ca/

Regards,

Paul.