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 possible 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 fin
tube efficiency of #112 type copper.006” thick absorber using
a 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. This is why Sun Ray Solar Copper Aluminum
absorber plates do not corrode.
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.