The silicon shortage, technological advances and rising costs are leading to innovative module technologies being developed into marketable products. Thus, in addition to the traditional and at present still dominant crystalline silicon technology, thin-film technology is increasingly coming onto the market.
Owing to a high degree of automation and efficient manufacturing processes, thin-film modules are cheaper to produce which is reflected in lower investment costs. Lower temperature coefficients and improved properties in poor light condition often result in higher energy yield in thin-film modules compared to crystalline modules. Having said that, the lower efficiency leads to a higher surface requirement and hence higher installation costs.
Whether you choose a crystalline or thin-film module therefore depends on the application in question. Given high temperatures, lower or diffuse irradiance and a plant alignment that is not ideal, thin-film systems clearly have the edge over their crystalline counterparts. The opposite is true in cases of high irradiance on tracking systems or where the surface area available is limited.
THIN-FILM TECHNOLOGY
Highly pure wafers of semi-conducting material (a-si, CdTe) are deposited or vapour-coated onto a carrying medium and provided with contacts. It takes less energy and raw materials to manufacture a thin-film photovoltaic module, which makes them more environmentally friendly and in the long-term cheaper to produce than crystalline modules. Other advantages are a lower temperature coefficient and the ability to use a broader light spectrum by means of multiple layers. The latter optimises efficiency and hence the yield. Thin-film modules also offer advantages in shady conditions, as the module output is only reduced by the portion of surface that is in the shade.
CRYSTALLINE SILICON
Wafer-thin disks are sliced off a silicon monocrystal (monocrystalline) or multicrystal (polycrystalline) and provided with contacts. The efficiency is higher than with thin-film cells of the same size. The colour of the monocrystal ranges from anthracite to dark blue and is uniform in appearance. Polycrystalline cells are slightly less efficient than monocrystalline cells (approx. 15 percent lower).
THE EFFICIENCY
Since crystalline silicon technology is more efficient than thin-film technology, a crystalline solar power plant requires less area in order to generate the same power output. Roughly speaking, to generate 1 kWp of power using crystalline technology requires approx. 8-10 m² compared to approx. 12-20 m² using thin-film technology.
The price of a solar power plant is determined by the installed output in kWp. For this reason the efficiency of a solar module is only of any relevance for the operator or investor if the earmarked area is very limited or needs to be paid by the square meter. In most other cases solar modules using thin-film technology meanwhile offer greater advantages in terms of both price and performance.
