Q. Are all copper absorber plates more efficient than a copper aluminum plate?
A. Some are and some are not. It depends on the construction of the absorber. To be specific the efficiency is dependent upon the thickness of the copper or aluminum, the distances between the tubes, the size and thickness of the tube and the method of which the absorber material is attached to the tube to create the heat transfer. This is called the “fin efficiency”.
The materials and method for heat transfer for the Sun Ray (all copper) and (copper aluminum) absorbers are selected for the maximum efficiency, Sun Ray (copper aluminum) absorbers are higher in efficiency then most (all copper) plates on the market. Sun Ray calculated its fin tube efficiency for an all copper plate 96%. Sun Ray’s copper aluminum plate came out 94%. Other examples for a comparison: A fintube efficiency of #112 type copper.006” thick absorber usinga weld to the age of a tube as a heat transfer method and the tubes are spaced 4.5″ apart will yield 89% efficiency.
Q. Do Sun Ray Solar Copper Aluminum absorber plates corrode?
A. Generally the dissimilar metals have a different electric charge, in this case copper, a noble metal with a positive charge (cathode), and aluminum, a less noble metal,with a negative charge (anode). If the two materials are in contact with a corrosive electrolyte like the water in car battery, corrosion will occur on the least noble material, the aluminum (anode) and decrease on the noblest metal, the copper (cathode). Similar to an anode rod in a water heater. This corrosion is called galvanic corrosion.
This is why Sun Ray Solar Copper Aluminum absorber plates do not corrode:
1. The two metals do not share corrosive electrolyte. The water is flowing inside the copper tubing and is not in direct contact with the aluminum.
2. The aluminum used in Sun Ray Absorbers is painted prior to its assembly to the copper tubing to create an electrical insulation between the two metals, eliminating an electrical current transfer.
Q. Are black chrome collectors more efficient than black painted collectors absorber plates?
A. For medium temperature collectors used in domestic water heating systems, black chrome-coated absorbers are not necessary. Black chrome can be used only if one is trying to generate steam. For the selective surface to be effective the absorber plate must be sealed in a vacuum collector housing (like a light bulb) otherwise the small increase in efficiency at the higher temperature range dose not justify the extra cost. In time, the black coating on some black chrome absorbers dissipate leaving the absorber with a shiny reflective surface and this is the exact opposite of what the absorber plate is design to do. A durable black baked paint over treated surface is our choice.
Q. What are the cost and efficiency differences between Sun Ray (all copper) Collectors and (copper aluminum) collectors?
A.The costs of all copper absorber solar collectors are about 20 % to 30% higher than the copper aluminum absorber collector. The copper aluminum collectors are only about 2% to 3 % less efficient. All one has to do is slightly increase the total collector’s surface area to make up the difference.