Technology

Entering the "gigawatt era" of solar manufacturing depends on making correct choices in two areas: 1: materials technology (solar cell type)  and 2: manufacturing technology that can sustain profitablility over the long term. Choosing the right  manufacturing technology is what enables taking full advantage of the material technology. These two elements must not only have  high efficiency and low cost, but also the ability to achieve high throughput and to be inherently reliable. Choice of the right combination of manufacturing technologies for CIGS is what sets Siva Power apart.

 

Siva's co-evaporated CIGS and MLI glass architecture provides the best combination of material technology and manufacturing technology. The benefit of Siva’s approach include:

 

1) highest efficiency thin film that now is on par with mc-Si

 

2) lowest cost enabled with fast deposition, high capacity tools, and low cost raw materials, with the fewest manufacturing steps (~1/2 of singulated cell approaches)

 

3) inherently reliable; avoids deleterious mechanical and metallurgical bonds as found with singulated cells

Material Technology

 

Three-stage co-evaporation of CIGS has been proven world-wide at leading institutes such as NREL, ZSW, EMPA, and HZB to be the ideal method to deposit CIGS.  Attributes of three-stage evaporation include:

 

  • High rate deposition: the CIGS layer forms directly without the need for lengthy reactions or atomic re-arrangement
  • Lowest cost raw materials: co-evaporation uses simple metal pellets, the lowest value-add state.
  • Highest efficiency: the film has a period where it becomes liquid, promoting liquid phase epitaxial growth of large, defect-free grains.

Manufacturing Technology

 

Key to our low-cost manufacturing is monolithic integration (MLI) on a glass substrate. In the MLI process,  the solar cells within a single glass substrate are series-connected via automated laser scribes. MLI has significantly fewer manufacturing steps compared to singulated cell approaches.

 

Our module uses a two-square meter glass substrate. The large format glass improves bankability by providing a drop-in replacement for mc-Si.  MLI avoids the mechanical and chemical connections that are found in Si and cell-based CIGS. This avoidance eliminates the possibility of corrosion or mechanical stress, the predominant factors that cause premature failure of cell-based CIGS modules in the field.  MLI on glass does not require diodes, which are a significant cost for stainless steel-based CIGS cell technology.