I Increase The Output Of the Solar Energy Capture Tubes?
You can add
a Sun reflector behind the solar thermal energy capture tubes
array, to increase the amount of sunshine arriving at, and collected
by the solar energy capture tube. When a simple flat plate reflector
is placed 2-3 inches behind the collector tube array, the thermal
energy collected by each tube will increase approximately 30-40%,
as more solar energy will hit the rear of the solar thermal
energy collector tubes.
Solar energy capture increases, can be achieved by using larger
curved reflectors to intercept larger areas af sunshine and
redirect that solar energy to a smaller "focus"
At the focus, a smaller more intense" image" of
the Sun is formed at the focus.
Trough and the Parabolic Trough solar collectors
are examples of so called "Imaging Solar Concentrators"
attempt to produce a smaller but more intense "image"
of Sol's energy
at the focal plane or focal line. Due to their" Imaging
geometry, (essentially adapted from telescope designs), the
aperture of the collector, must directly face the sun, to
avoid loss of
collection efficiency, and to maintain the co-location, of
the "solar Image,"
with the solar energy receiver, or absorber. These types of
trough collectors, require complex, and expensive mechanical
tracking devices, just to keep them pointed always at the
A more sophisticated parabolic collector trough can be
Designed, that avoids the need to track the sun altogether,
combining two parabolas together, to form the "Compound
Parabolic Trough Solar Collector."
are not forever. They are a bargain struck to give an inventor,
like Roland Winston, some market protection, but only for
a limited time, in exchange for the inventor, giving a wonderful
new idea to the world!
Winston's 1977 patent has now expired, and thus his idea for
a Non-Tracking Compound Parabola Solar Concentrating Collector
is now in the "Public Domain." That means than anyone
and everyone, is now free, and legally entitled, to make use
of, or even market and sell the invention, without any need
to pay royalties to the inventor.
Optical Outward facing Compound parabolas are useful for Non-Tracking,
Concentrating Solar Energy Collectors that redirect Solar
Insolation onto a flat plane at the rear of the solar energy
These can increase the output of simple solar cells several
Properly Designed Inward-Facing, Non-Imaging, Non-tracking
Compound Parabola Solar Concentrators, Can Redirect Solar
Insolation Energy, from many different Sun angles, throughout
the day, to a stationary Co-Focal point!
Parabola Solar Energy Concentrators can also be designed as
a trough shaped solar energy collector.
When this is done, the co-focal point then becomes a co-focal
If a coolant filled pipe solar energy absorber pipe, or a
tubular evacuated tube solar energy absorber tube is co-located
at the co-focal line, there will then be a maximum of concentrated
Solar energy delivered and transferred to the energy absorber
Non-Imaging Optics that do not require telescope-like aiming
to preserve a distortion free image of the sun, we can also
avoid the need to keep the collector pointed directly at the
sun. We can thus still concentrate the sun's energy with out
needing to keep the solar energy collector reflector mirror
pointed directly at the sun. We need only to collect and concentrate
the Sol's total energy, irrespective of any need to create
or preserve a precise optical solar image. By selecting non-imaging
optics we can thus avoid the need to keep the collector aperture
pointed at the sun. Instead, we can collect and concentrate
Solar Energy from multiple directions separately or at once.
So while the sun moves across the sky, we can still accept
and concentrate the Solar Thermal Energy all day using a properly
designed compound Parabolic Trough Concentrating Solar Collector
coupled with Evacuated (vacuum) tube Solar energy Capture
Tubes. Using this type of collector, the output energy if
a Solar Energy Capture Tube can be increased by a factor of
4- 6 times using a stationary solar collector. Concentration
ratio is similar to the ratio between the area of the Solar
Capture tube, and the size of the larger collector aperture
area. The upper limit of the power output will be the glass
softening temperature and the maximum allowable thermal expansion
and contraction permitted by the vacuum seal glass-to glass
Such solar collectors do not need tracking, and require only
occasional season angle adjustments (several times a year)
are required to keep the aperture perpendicular to the noonday
sun, to the maintain maximum power output!
of such Compound Parabolic concentrators has the co-focal
lines running East -to-West. The seasonal tilt required, just
points the array to face more to the southern horizon, when
the sun is lowest, at the winter solstice. As the sun rises
higher in the spring and summer, the tilt is reduced, to make
the array point more generally toward the zenith. The correct
angle is simple to determine, just make the seasonal adjustment
at least six times a year, no more than two months apart,
and do it at noon, by simply pointing at the noonday sun.
Then, no daily tracking at all is required!
Thick thermal foam blocks can be hot-template-sculpted to
create the compound parabola shape and then covered with aluminized
Mylar to create very inexpensive Solar energy reflector mirrors!
the fixed Non-Tracking Concentrator Collector Array should
be covered with a glass plate to keep out rain, snow, dirt,
leaves, and wind blown debris, which can dirty the reflectors,
and reduce Solar energy output.
A cheaper alternative is to omit the glass and regularly clean
the mirrors every two weeks or so.
A slight chevron tilt as shown above can be used to provide
low cost rain-water drainage as well as assist thermo-siphon
flow, in systems without circulation pumps or, in systems
that utilize gravity return, of the colder, denser coolant
fluids to the lowest levels in the Solar Energy capture Tubes.