Crystalline silicon was the original materials technology used by the PV industry to manufacture solar cells.  First widely used in space satellites, conventional crystalline silicon solar cells are fabricated in a step-and-repeat, batch process from small wafers of single crystal or polycrystalline silicon semiconductor materials.  Although, substantial advances have been made in the development of this technology, the cost of crystalline PV modules is still high because of materials costs and numerous processing steps that are needed to manufacture the modules. Crystalline silicon solar modules are bulky, break easily, and consume more energy in manufacturing.

Another thin-film technology for producing solar cells contains cadmium. Not environmentally friendly, and requiring great care be taken during manufacturing and after sale. These thin-film technologies, as well as crystalline silicon technology, employ a step-and-repeat batch process, whereas the cells shown below were manufactured using a a continuous roll manufacturing process described herein.



Tandem Junction Cells


Thin-film amorphous silicon, 175mm x 60mm (less than 1mm thick)

Output 330mA and 1.2V (stable), a usable current/voltage characteristic, open circuit 2V in full sunlight

Flexible, virtually unbreakable

Light-weight (19g with pinch terminals), waterproof, high power/weight ratio

Durable, 20year useful life

applicable to all climates because it also responds to light scattered by cloud cover

(please note these cells are discontinued)



Triple Junction Cell Specifications (1-Q laminate):


Thin-film amorphous silicon, 190mm x 57mm (1mm thick)

Output 330mA and 1.5V (stable)

Flexible, virtually unbreakable

Light-weight (23g with pinch terminals)

Waterproof, high power/weight ratio

Durable, 20year useful life

responds to diffuse light scattered by cloud cover

You can purchase the above cells from Wholesale price list >>  Plugging Into The Sun

The above flexible solar cells are based on a sophisticated multi-layer amorphous silicon thin-film solar cell developed originally by Energy Conversion Devices, Inc, USA. This spectrum-splitting cell, shown schematically below, is constructed of separate p-i-n type, amorphous semiconductor solar sub-cells, each with a different spectral response characteristic. This allows the cell to convert the different visible and near infrared wavelengths of sunlight with optimal efficiency. This spectrum-splitting multijunction design now holds all the world's records for amorphous silicon solar cell efficiency, including the highest stable efficiency measured by the National Renewable Energy Laboratory (NREL) for a small-area amorphous silicon solar cell @ 13 percent.




Using their own thin-film, vapor-deposited amorphous silicon (a-Si) alloy materials, Uni-Solar have developed proprietary technology to reduce the materials cost in a solar cell. Because a-Si absorbs light more efficiently than its crystalline counterpart, the a-Si solar cell thickness can be 100 times less, thereby significantly reducing materials cost. By utilizing a flexible, stainless steel substrate and polymer-based encapsulates, PV products utilizing our technology can be very lightweight, flexible and durable. No broken parts during shipping and easy to transport to remote rural areas, thus saving shipping costs, and can be installed without breakage.

Amorphous cells with different light absorption properties deposited continuously, one on top of another, to capture the broad solar spectrum more effectively. This increases the energy conversion efficiency of the multi-cell device and improves performance stability. The multi-junction approach has resulted in world record efficiencies for these cells. 
Each of the nine thin-film semiconductor layers that comprise the cell is sequentially deposited in separate, dynamically-isolated, plasma enhanced chemical vapor deposition (PECVD) chambers as the stainless steel substrate progresses through the machine.

To further reduce the manufacturing cost of PV modules, they have pioneered the development of and have the fundamental patents on a unique approach utilizing proprietary continuous roll-to-roll solar cell deposition process. Using a roll of flexible stainless steel that is a half-mile long and 14 inches wide, nine thin-film layers of a-Si alloy are deposited sequentially in a high yield, automated machine to make a continuous, three-cell stacked structure. The roll of solar cell material is processed further for use in a variety of photovoltaic products. 


Uni-Solar have an annual production capacity of 5MW that is now being expanded to 30MW by the addition of a new facility located in Auburn Hills, MI. This plant is fully automated and allows simultaneous processing of six rolls of stainless steel, each 1 1/2 miles long, during deposition of the a-Si layers.  The thin-film materials, cell designs, and manufacturing processes used by United Solar Systems Corp. are protected by more than 160 issued U.S. patents.


Find out more from: United Solar Systems Corp.

CONTACT:  nelson@solarnavigator.com  07905 147709 (UK)


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