Conversation with Bob at SunEarth on March 23, 2008

return to Solar Thermal Collectors

Here's a summary:

• the panels can be placed either portrait or landscape
• the maximum panels in parallel on one manifold is 6 without running the risk of leaks..."never seen one with more than six panels go more than 10 years without a leak." It is do to expansion and contraction of the long manifold vs. the panel frame. So an answer is one pipe feeding two manifolds each feeding five panels.

(AR: Another approach is to use a low (atmospheric) pressure drainback system and to make each connection with high temp silicone radiator hose. We have been doing this on all our drainbacks and it is not putting any undue stresses on the collectors.)

• Need EC (Chrome) feature which are intended for colder climates
• There is a "1.5" version that has a 1.5" header for greater flow potential
• Overheading / Heat dump
  • He has covered the panels...often recommends doing so
  • paint the panels with poster paint that washes off.
  • uses radiator coils with fans to dump heat
• List price for Empire 4x10 is $1,300 ($31.7/sf) he said if you order 12 there is a price break.
• delta T for T in - T out is 15 - 25F; it creates a step function with the tank...causing a rise up every time it goes through the loop.
• he has seen the PV pumps work.
  • pluses: runs even in with no power (outage), sun goes up = flow goes up
  • negatives: no control
  • recommends multiple pumps and close monitoring
• durability: panels should last 50yrs; the main thing to watch is fluid maintenance
• Pressure: the pressure is fixed once the system is charged up...assuming a glycol system
• Storage Tanks: Contact Bob Perkins at Morey Manufacturing in CA on xxx Valley he's been doing it for 30 yrs