High efficiency solar cells are for the moment only available to space applications, because of their prohibitive costs. The Eindhoven University of Technology from The Netherlands, with a EUR 1.2 million help from the Dutch government wants to develop ultra-efficient solar cells that are also cheap. They envision their cells having a 65% efficiency, something even the satellites would envy.
Currently, thin film solar cells employ an efficiency somewhere around 40 percent. Recent studies and prototypes made with concentrated solar panels revealed a conversion of 41%, but the researchers from TU/ want more. They will use mirror systems that concentrate the light one thousand times and use very little material for the actual solar cells, which would be very expensive otherwise if used at full scale.
Jos Haverkort, one of the researchers, said: “If the Netherlands wants to timely participate in a commercial exploitation of nanowire solar cells, there is a great urgency to get on board now.” The research is conducted together with Philips MiPlaza.
Their idea on how to make their dream possible relies on stacking a number of subcells(junctions) in each cell, in which each subcell has to convert a certain spectrum of light optimally into electricity. The best nanowire solar cell made to this day has an 8.4 percent efficiency. The Dutch researchers want to encase the nanowires in protective shells in order to obtain the same high efficiency as with thin-film cells. Haverkort believes that 5 to 10 junctions will be enough to boost the solar cell having the desired 65 percent efficiency.
Production costs are also slashed by their proposed technology, because the nanowires that make their solar cells can be grown on cheap silicon substrate and also grow faster. Gallium and Indium, the two expensive and rare materials that they will use for the tiny solar cells will be used very scarcely.
A few years ago, the price of solar cells was at around $3/watt. Now it is almost $2/watt (even lower). After the scientists from Eindhoven will have finished their work and the market will have gladly accepted their solar cells, the price should fall lower than 50 cents per watt, which sounds incredible. We’ll wait and we’ll see.