solar collector 4 : absorbers

time to start building the actual absorbers or collectors. at this moment i'm building two collectors each about one square meter large that coupled together will function as one. in a later stage i'll build a third and a fourth collector.

these are the parts that'll make up the collector : ten meters of soft copper tube, one m² of aluminum sheet and plywood and a couple of hundred stainless steel staples.




the collector is build on a sheet of plywood. this material is a good insulator, it can withstand relatively high temperatures (usable to about 100 °c) and tough. the copper tube is laid out in a serpentine pattern. on top of the copper comes the aluminium sheets that are bend around the copper.



in the example i'm working from silly putty is used to bond the aluminium and the copper but i decided not to use it : it's meant to fill all the gaps between the copper and aluminium to optimize heat transfer. however silly putty is an excellent insulator and a thin layer of silly putty seperating all of the copper and aluminium would actualy prevent heat transfer. i estimate that about half the tube is in contact with the aluminium which should be just fine.


the aluminium is 0.3 mm thick and i bought it in pieces 20 by 40 cm large. it's easy to work with and bending it exactly to the copper tubes diameter was easy. the other end of the sheets fits underneath the tube so the copper is completely surrounded by aluminium. the aluminium is stapled to the plywood.

last step are a couple of coats of heat resistant paint - the kind that is used to paint engine blocks - to enhance heat absorption.


next step : the frame.