WIDE ACCEPTANCE ANGLE, HIGH
CONCENTRATION RATIO, OPTICAL COLLECTOR
This solar energy
concentrator provides a way to focus the solar rays coming from the sun
onto a small area using two mirrors. The first mirror has a spherical
shape and focuses the solar ray onto a second mirror. The second mirror
has multiple curvatures, which allow it to focus not only the solar rays
coming in aligned, but to also include those that may be coming in slightly
out of alignment, onto a small area. In this small area where the solar
energy is concentrated, one can then place a device to convert the solar
energy into a useful form, by using solar cells (photovoltaics) to generate
electricity, or a heat exchanger (photothermal converter) to generate
heat.
Potential Commercial Uses
This solar energy concentrator
(mirrors) can be used in either a photovoltaic or photothermal concentrator
system, or both. As an integral part of a photovoltaic system located on
the roof of a building, it can assist in producing electricity, which can
be used in parallel with the local utility providing electrical energy to
augment and share the load. The photovoltaic cells, used with this concentrator
and located at the focal point of the secondary mirror is likely to get
hotter than is tolerable by the cells, requiring cooling. If cooling is
required, the thermal energy removed from the solar cells during the cooling
process can be used to augment the heating of a building during winter months.
When used with a photothermal converter, the solar radiation is converted
into heat, from which electric power can be generated, or used in heating
and cooling the space in a building, as well as in desalination plants and
other industrial applications which require heat or steam.
Benefits
The concentrator provides
both a high-concentration ratio and a wide acceptance angle. It is capable
of tolerating a small amount of misalignment, which makes it easier to install,
thereby eliminating the need for special training of the installer. It captures
a greater amount of off-axis light than the currently vailable cassegrain
collectors.
The Technology
The collector is capable
of improved collection of off-axis radiation at high- concentration ratios.
The primary concave mirror receives and reflects the incoming radiation
on to the secondary mirror. The secondary mirror is aligned coaxially and
spaced in relation to the primary mirror. The secondary mirror edirects
and concentrates the radiation received from the primary mirror onto a photovoltaic
or hotothermal converter. The secondary mirror has three different zones:
inner, central, and outer. The central zone has a hyperboloid cross sectional
shape, which reflects on-axis radiation from the primary mirror. The inner
and outer zones of the secondary mirror have paraboloidal cross sectional
shapes, which reflect the off-axis radiation from the primary mirror onto
the photovoltaic or photothermal converters.
Options for Commercialization
This solar energy concentrator
device is part of the NASA Technology Transfer Program available to industry.
A patent for the system has been issued to Marshall Space Flight Center
and is available for licensing.
Patent Number
5,062,899
Contact for Licensing Information
Technology Transfer Office
Patent Licensing Information
Mail Code CD30
Marshall Space Flight Center, AL 35812
Key Words
Concentrator
Solar Heating
Wide Acceptance Angle
Solar Energy
Available
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