Solar
Collectors use absorber plates to increase collector efficiency. Absorber plates
do this by increasing the surface area exposed to sunlight. More than 700 linear feet of
copper tubing would be required to cover the same surface area that could be
covered with 60 linear feet bonded to a well-constructed absorber plate.
Individual aluminum heat fins, normally used with radiant floor heating systems,
may also be used to assemble the absorber plates used in a serpentine collector.
A 4x8 collector would require sixteen 6"x20" heat fins. An absorber
plate may also be constructed from two 10' x 20" sheets of aluminum
flashing commonly available from construction suppliers such as Home
Depot.
Copper
absorber plates may be soldered directly to Copper flow tubes, but a 4'x8' sheet
of copper is expensive and the soldering process is tedious. Serpentine collectors that use
either Copper or PEX bonded to Aluminum are cost effective.
PEX tubes may be installed under aluminum absorber plates and staples may be
used to hold the PEX against the aluminum. An alternative to this method
involves the installation of a copper flow tube on
top of the aluminum. The on-top installation is made possible by the ridged
nature of
copper held down with side and central supports.
This method of
serpentine collector fabrication was specifically designed for
3/8" copper. If you have a preference for PEX check out GARY'S PEX
Collector or learn about Modified Trickle Down Solar
Collectors that do not use metallic flow
tubes or metallic absorber
plates.
With
a little luck a finished serpentine collectors may look something like this. A 50' roll
of 20 " wide .0086 gauge flashing is enough
to make the absorber plates for two 4x8 collectors with a 10' piece of aluminum
left over. Click on the left illustration for more information on this
serpentine collector.
Let's
now focus on the fabrication of the 20" x 94" absorber plate.
Tools
and Materials
1. Aluminum
flashing .0086" x 20" x 50' for two 4x8 collectors
2. A pounding jig
made from 1x6 boards and 1 1/4" drywall screws. 3. A heavy mason's
hammer.
4. Tin snips.
5. Six 7/16" steel
rods about 24" long.
Fasten the top layer of boards to the base platform with 1¼-inch drywall
screws. The most important consideration in the construction of this jig is the
spacing between the boards. The ½ inch spaces should be centered 6 inches
apart, and the pounding jig should look something like this when you’re
done.
Side supports act as guides that hold
the aluminum straight while pounding. Since the aluminum is 20" wide. I
recommend boards 20.2" This will allow a little wiggle room between the
guides. Of course the 20.2" boards are perpendicular to the 48" boards
and the 20.2 boards should be parallel to each other with 1/2" slots
between them. Use 7/16" rods to help space the slots. After 15 bends are
made in the aluminum the distance between the first bend and the last bend
will be about 90" for a 4x8 collector.
Without the guides pounding grooves into the aluminum is
tedious.
See what I mean?
The jig with side supports is easier to work with and the finished absorber
plate also looks better.
POUNDING OUT ABSORBER PLATES
STEP ONE
Lay in a 20 inch wide sheet of aluminum. This one is 50 inches long. long but
you’ll be using one that’s 10'long.
Just slide the 10' long sheet of aluminum through the jig after the first 10
slots are pounded into the jig.
STEP TWO: Place the 7/16 inch steel rods in the slots.
STEP THREE:After
the first rod is pounded into position it’s held in place with a piece of
plywood that you’ll kneel on so that the next rod may be pounded without
disturbing the first. This process may be repeated until all the groves are
placed in the aluminum, To pound grooves in sheets longer than a jig simply
shift the sheet down and place the last groove from the last slot into the first
slot.
Congratulationsonhammering
outyour first
absorber plate. May this be the first of many… All you have to do now is pound
out 7 more and you’ll have enough collectors for a96 sq ft array. Keep on trucking. Connecting with the sun is
not always an easy alternative but it is our only alternative if we are to live
in harmony with our planet and the forces of nature. If closed loop serpentine
collectors seem a little to messy for your taste you could always explore the possibilities
of MTD solar heating or other green energy alternatives.
Copper
absorber plates may be soldered directly to Copper flow tubes, but a 4'x8' sheet
of copper is expensive and the soldering process is tedious. Serpentine collectors that use
either Copper or PEX bonded to Aluminum are cost effective.
