While the theoretical benefits of CdTe and other thin film technologies have long been recognized, First Solar’s successful scale up demonstrates the actual production of high performance CdTe modules in volume, transitioning the technology from the “development” to “growth” phase. Multiple years of field data are now available to demonstrate First Solar’s efficiencies, high energy yields and excellent system performance ratios. CdTe module production facilities are today, even at the early stages of commercial production, achieving levels that required many years of production experience to achieve with traditional technology. Repeatable production processes have been fully demonstrated, enabling large scale expansion of CdTe module production.

This success is, to a significant extent, attributable to the unique physical properties of CdTe which make it ideal for converting solar energy into useful electricity.

• CdTe is a direct bandgap semiconductor, which enables it to convert solar energy into electricity more efficiently (i.e., more watts per kg of material) than the indirect bandgap semiconductor materials used historically.
  The energy bandgap of CdTe, at 1.45ev, enables it to convert more energy from the solar spectrum than the lower energy bandgap materials (1.20ev) used historically. As a result, CdTe is capable of converting solar energy into electricity at an efficiency rate comparable to historical technologies with about 1% of the semiconductor material requirement.
  
  
• CdTe will generally produce more electricity under real world conditions than solar modules with comparable powered ratings.
  Solar cells become less efficient at converting solar energy into electricity as their cell temperatures increase. However, the efficiency of CdTe is less susceptible to cell temperature increases, enabling CdTe solar modules to generate relatively more electricity under high ambient (and therefore high cell) temperatures. CdTe also absorbs low and diffuse light and more efficiently converts it to electricity under cloudy weather and dawn and dusk conditions where conventional cells operate less efficiently. As a result, CdTe will generally produce more electricity under real world conditions than conventional solar module with similar power ratings.
  
  
• CdTe permits simple device structures and processes, leading to low cost production.  
  The robustness of CdTe enables relatively simple device structures and production processes. High performance modules are achieved with single junction, polycrystalline devices. Automated high throughput production processes have been employed successfully with CdTe, without the need for expensive clean rooms or other expensive specialty equipment.
  
  
• Abundant raw CdTe material to support high volume production and demand.
  CdTe is made by transforming cadmium and tellurium into a stable, inert semiconductor. Both elemental materials are produced as byproducts of mining processes (primarily zinc mining and copper refining) and present in abundant quantities to support multi-GWs of annual production

These attributes have led the National Renewable Energy Laboratory in Golden, Colorado to recognize CdTe’s potential for achieving the lowest production costs among current thin film technologies. (Photon International, November 2004, page 50). CdTe module costs well below $1.00/Wp have been predicted by NREL and others.