Micromorph
As micromorph (engl. Micromorph) which is solar cell concept referred to that to increase the energy efficiency of a first absorber for blue light with a second absorber for red light by means of thin silicon layers uses.
Surname
The crystallographic term "microcrystalline" denotes a conglomerate of micrometer-long crystallites that can be used for the red absorber in the case of microcrystalline silicon, whereas " amorphous " is the crystallographic term for mostly non-crystalline ordered solids and in the case of amorphous silicon for the blue absorber is used. The word creation “micromorph” describes a tandem solar cell , also known as a stack solar cell, consisting of thin layers of microcrystalline silicon and amorphous silicon.
history
The history of the micromorphous solar cell has not yet been written down. Called the “dead duck” by skeptics, the thin-film solar cell, to which the micromorph solar cell is counted, has eked an erratic existence since the early 1980s: at a time when the cut, crystalline wafers had a diameter of 5 cm (2 inches ) and served as the basis for integrated circuits and occasionally also for solar cells, a thin-film module with an edge length of 30 cm was considered a large energy-producing surface. Even today, a thin-film module still essentially consists of a contact layer made of a transparent, electrically conductive oxide (TCO), a light-absorbing solar cell material and a back contact. Early thermodynamic considerations led to the insight that the energetic efficiency of solar cells could be increased considerably if, instead of a single light-absorbing material, a sequence of several slightly different light-absorbing materials could be combined: the stacked solar cell was proposed early on. A stacked solar cell with slightly varying optical properties is advantageous.
The micromorph solar cell connects two slightly different, light-absorbing silicon layers in a technologically elegant way, with a first unit only absorbing blue light and a second unit making do with the red light of the solar spectrum . To manufacture the two stacked units, only different manufacturing processes, but not fundamentally different machines, had to be available.
Technology advantages
Micromorph solar modules have been manufactured commercially since 2001. The pioneer in developing industrial production methods was the Japanese company Kaneka , followed by the mechanical engineering company Oerlikon Solar from Switzerland and the mechanical engineering company Applied Materials from the United States . Other system manufacturers such as Leybold Optics and ULVAC followed, so that considerable industrial knowledge was built up. The result of this knowledge is, on the one hand, solar modules with an area of 5.7 m², which achieve efficiencies of 10%. Manufacturers of such full-size modules are Masdar and ENN. In addition to the ability to manufacture large modules with guarantees of over 20 years, the low material consumption of silicon is often mentioned. Furthermore, a favorable temperature coefficient is considered to be the best trump card of micromorph solar cells: the hotter the module is when exposed to sunlight, the greater the reduced output. Polycrystalline solar modules lose 5% of their nominal power to 10 ° C, micromorph solar modules only 3%. Large solar parks can thus produce solar power very inexpensively with micromorphous solar cells. However, these technological advantages are offset by higher system costs (BOS) and a market with very low material prices.
Market situation
Worldwide production of thin-film solar technologies ( CdTe , CIGS and micromorph) recorded a market share of 13% or around 3.8 GW in 2010 ; 45% or 1.7 GW of this was due to micromorph solar technology.