heat transfer fluid makes the collector solar absorptive the solar absorptive heat transfer fluid enters through bottom header 861 fills the absorber center conduits of the absorber assembly 801 then exits through top header 860 as noted previously the solar absorptive heat transfer fluid flow direction may be reversed in one specific exemplary implementation the length a is approximately 96 inches the width b is approximately 48 inches the absorber thickness is approximately 0 02 inches c_d is 0 5 inches i_d is 1 0 inch n is 48 and l_s is 12 inches the collector assembly may weigh less than approximately 25 pounds hold less than 5 gallons of fluid operate with vacuum insulation and be manufactured inexpensively in another specific exemplary implementation the length a is approximately 20 feet the width b is approximately 10 feet the absorber thickness is approximately 0 02 inches c_d is 3 inches i_d is 6 inches n is 20 and l_s is 12 inches the center conduit makes use of the configuration defined by 830 1 this collector assembly which collects solar energy over an approximate 200 square foot area assembles in a modular fashion the entire assembly may weigh less than 200 pounds holds less than 20 gallons of fluid operates with air as the insulator and may be manufactured and installed inexpensively referring now to fig1 headers 60 and 62 are described in greater detail the bottom header 60 being representative of the top header 62.