Photovoltaic modules - Technical and economic aspects

We're all aware of the difficulties encountered by the crystalline silicon sector in its early days, when it tried to launch its career as a replacement for diesel generators in an unsolvent market (African pumps) with immense needs, and in a solvent market (radio-relay systems) with relatively limited needs. One might therefore think a priori that if thin-film technology is unable to replace crystalline technology in terms of lower production costs and similar performance, its future is in serious jeopardy. But this would be to overlook the competitive advantages of thin-film technology.

The characteristics of thin-film photovoltaic cells which, in certain applications, can make them more attractive or more efficient than crystalline cells are :

• the great flexibility of size and shape, making it possible to create customized modules;

• aesthetics (dark, homogeneous and uniform color, serial cell connections almost invisible to the eye);

• a wide range of voltages and currents, the limits of which are set only by optimized bandwidths;

• the possibility of making them truly semi-transparent ;

• the possibility of integrating them on all kinds of substrates, especially flexible ones;

• the ability to make small-scale 12 V generators much cheaper than equivalent crystalline generators (penalized by the cutting and assembly costs of small cells);

• the ability to make very large monolithic generators (up to 2 m ² ).

Thin-film photovoltaic technologies will have to overcome several obstacles in their quest to lower costs and become competitive with traditional sources of electricity.

Irrespective of the commercial aspects, distribution channels and distributor margins, which currently govern the final selling price to the consumer, seen from the industrial producer's point of view, to improve module costs it is necessary to make progress on three fronts:

• module performance (yield or Wp/m ² ) ;

• manufacturing cost (€/m ² ) ;

• production volume (economies of scale).