Dr. Mabuse skrev:
Det stora problemet är att vi bara får in ca 1000w/m² energi i form av strålning från solen. Vi behöver PV-celler som kan omvandla större bandbredder.
Vet inte om du tänker på:
http://en.wikipedia.org/wiki/Solar_cellCitat:
Gallium arsenide multijunction
Main article: Multijunction photovoltaic cell
High-efficiency multijunction cells were originally developed for special applications such as satellites and space exploration, but at present, their use in terrestrial concentrators might be the lowest cost alternative in terms of $/kWh and $/W.[32] These multijunction cells consist of multiple thin films produced using metalorganic vapour phase epitaxy. A triple-junction cell, for example, may consist of the semiconductors: GaAs, Ge, and GaInP2.[33] Each type of semiconductor will have a characteristic band gap energy which, loosely speaking, causes it to absorb light most efficiently at a certain color, or more precisely, to absorb electromagnetic radiation over a portion of the spectrum. The semiconductors are carefully chosen to absorb nearly all of the solar spectrum, thus generating electricity from as much of the solar energy as possible.
GaAs based multijunction devices are the most efficient solar cells to date. In April 2011, triple junction metamorphic cell reached a record high of 43.5%.[34] This technology is currently being utilized in the Mars Exploration Rover missions, which have run far past their 90 day design life.
Men det ska ju vara billigt också. Använder tydligen en del dyra råmaterial:
Citat:
Tandem solar cells based on monolithic, series connected, gallium indium phosphide (GaInP), gallium arsenide GaAs, and germanium Ge p-n junctions, are seeing demand rapidly rise. Between December 2006 and December 2007, the cost of 4N gallium metal rose from about $350 per kg to $680 per kg. Additionally, germanium metal prices have risen substantially to $1000–1200 per kg this year. Those materials include gallium (4N, 6N and 7N Ga), arsenic (4N, 6N and 7N) and germanium, pyrolitic boron nitride (pBN) crucibles for growing crystals, and boron oxide, these products are critical to the entire substrate manufacturing industry.
Men man arbetar på att få ner materialåtgången;
Citat:
The Dutch Radboud University Nijmegen set the record for thin film solar cell efficiency using a single junction GaAs to 25.8% in August 2008 using only 4 µm thick GaAs layer which can be transferred from a wafer base to glass or plastic film.