Method for producing a carrier material for the solar cells of a solar generator

A method for producing a carrier material for use in a solar generator composed of a plurality of solar cells electrically conductively connected together and fastened to the carrier material. The method includes providing a glass fiber fabric composed of intersecting glass fibers; applying liquid plastic composed of a plastic dissolved in a solvent to the points of intersection of the glass fibers; evaporating the solvent; and hardening the plastic so that the glass fibers are firmly mechanically connected together by the hardened plastic at the points of intersection.

BACKGROUND OF THE INVENTION 
The present invention relates to a method for producing a carrier material 
for use in a solar generator, wherein the solar generator is composed of a 
plurality of solar cells electrically conductively connected together and 
fastened to the carrier material. 
Carrier materials for accommodating the solar cells of a solar generator, 
particularly a flexible solar generator for space travel, are known in the 
form of pure plastic sheets, and reinforced glass fiber or reinforced 
carbon fiber sheets. These sheets have the drawback that they are either 
too heavy, too opaque or not stiff enough. When used in solar generators 
for space travel they exhibit the additional drawbacks that they absorb 
the infrared (IR) radiation from the sun and/or the earth and thus 
undesirably contribute to an increase in operating temperature. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a method for 
the manufacture of a solar cell carrier material which simultaneously has 
low weight, high light permeability and the greatest possible stiffness. 
The above and other objects are accomplished in accordance with the 
invention by the provision of a solar cell carrier material which is 
manufactured by a method including: 
providing a glass fiber fabric composed of intersecting glass fibers; 
applying liquid plastic composed of a plastic dissolved in a solvent to the 
points of intersection of the glass fibers; 
evaporating the solvent; and 
hardening the plastic so that the glass fibers are firmly mechanically 
connected together by the hardened plastic at the points of intersection. 
The significant advantage of the present invention is seen to be the 
avoidance of the above-mentioned drawbacks which occur with use of the 
prior art sheets used for solar cell carrier material.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, two solar cells 2 and 3 are glued to a carrier 
material 1, composed of glass fiber fabric, via an adhesive layer 4 which 
is preferably composed of transparent silicone rubber. Normally, the 
adhesive is applied to the carrier material 1 or to the undersides of 
solar cells 2 and 3, respectively, through screen-printing masks. Solar 
cells 2 and 3 are electrically conductively connected together by means of 
a connector 5 and their upper faces are covered by glass covers 6 and 7, 
respectively. Instead of being fastened to the back of the solar cells as 
illustrated, the glass fiber fabric carrier 1 can be fastened to the front 
active sides of the solar cells so as to replace the glass covers 6 and 7 
and to simultaneously act as a carrier material (substrate). A transparent 
silicone adhesive may be used as the fastening means. 
According to the invention the carrier material 1 is a glass fiber fabric, 
preferably provided with a pattern of openings realized by defined pitches 
between warp or weft filaments. A liquid plastic, for example polyester, 
polyimides and polycarbonates, is applied to the points of intersection of 
the glass fibers. After evaporation of the solvent contained in the liquid 
plastic and/or polymerization or otherwise hardening of the liquid plastic 
by a heat treatment the glass fibers are firmly mechanically bonded to one 
another at the points of intersection. The glass fiber fabric can then 
additionally be reinforced if necessary at given locations by means of 
plastics. This may be done by means of plastic sheets which are liquid 
when dissolved in solvents and which do not become solid again until after 
the solvent has evaporated and/or they have hardened. Examples for such 
plastics are also polyester, polyimides and polycarbonates. 
The liquid plastic is applied to the glass fiber fabric provided with the 
opening pattern so as to partially or completely saturate the glass fiber 
fabric with the liquid plastic, or the liquid plastic is applied to the 
points of intersection or the locations in the glass fiber fabric to be 
reinforced, by means of a brush, a roller or a mask, or by 
screen-printing. 
FIG. 2 shows part of a glass fiber fabric, which includes a warp fiber 8, 
six weft fibers 9 and the plastic 10 which connects the fibers at their 
points of intersection according to the invention. The additional 
reinforcement 11 is also shown in FIG. 2. 
A solar generator equipped with such a glass fiber fabric is distinguished 
by low absorption of IR radiation. The IR radiation passes through the 
solar generator without producing a noticeable increase in temperature. 
The result is a lower operating temperature and thus an increase in 
performance. 
Preferably, a solar generator constructed according to the invention will 
utilize solar cells having rear contacts in the form of a grid finger 
system similar to that of their front sides rather than a planar silver 
contact. This is necessary for ultra-thin solar cells, inter alia, to 
minimize the high curvature of the solar cells which would otherwise be 
caused by a rear contact of planar silver. 
The increase in performance resulting from low operating temperatures of a 
solar generator constructed according to the invention is of interest 
primarily for geostationary satellite paths which have an orbital radius 
of 36,000 km. For low earth orbits (300-1000 km), the performance of the 
solar generator may be further increased by using rear-active solar cells 
which additionally convert the radiation emanating from the earth (earth 
albedo) into electrical energy. 
One glass fiber which can be used is Interglass 90240. It is understood 
that other fibers of plastic or inorganic origin can be used. 
It will be understood that the above description of the present invention 
is susceptible to various modifications, changes and adaptations, and the 
same are intended to be comprehended within the meaning and range of 
equivalents of the appended claims.