A ray of light for advanced solar energy
Solar energy technology has been improving in recent years, but has not come close to making use of the full solar spectrum in order to improve efficiency. To date there was no way that solar cells could exploit the lower parts of the solar spectrum which simply could not be absorbed by the materials inside them. The EU-funded project 'A new PV wave making more efficient use of the solar spectrum' (Fullspectrum) took up the challenge to produce electricity from solar sources more efficiently. Using multi-junction solar cells, the project aimed at inching towards a record high of 40 % solar efficiency. It achieved the best results using monolithical triple-junction solar cells. On another front, the project worked on thermophotovoltaics (TVP) to better exploit the solar spectrum using special wafers and the power of the Sun to heat specifically conceived emitters. In addition, the project improved the use of the solar spectrum by using particular materials that enhance absorption, a task supported by calculations in quantum mechanics. It also investigated molecular-based concepts, i.e. development of flat concentrators, dye cells and up-and-down converters for solar cells, particularly those that work well with multi-junction cell components. Towards the end of the project Fullspectrum produced industrial prototypes of multi-junction solar cells with compact concentrators and tested their efficiency. It achieved 5 world records in terms of efficiency, including 37.6 % efficiency at 1,700 Sun units for its triple-junction cell prototypes. The resulting compact high-concentration modules and concentrator characterisation tools, whose designs are ready for mass production, will up the ante in solar energy efficiency if the technology is exploited.
