Solar energy is a power source that has long been sought to implement for wide spread consumer use worldwide. The factor currently inhibiting its global integration into the power grid is attributed to its high production and maintenance cost. Although solar power is one of the truest renewable energy sources its integration in the modern power grid has been a slow process to say the least. All of this could change soon however due to research being conducted by scientists in Denmark and Switzerland from the Nano-Science Center and Ecole Polytechnique Federale de Lausanne.
The latest developments in solar technology have come about from the use of a type of nanowire which can concentrate light an estimated 15 times higher than normal sun light. These nanowires contain a light absorption property that enables them to concentrate the amount of sunlight absorbed by the silicon materials used in solar cells. Peter Krogstrup PhD published an article about the possibilities of the application of these nanowires to generate a greater amount of solar energy in the journal of “Nature Photonics”.
The nanotechnology used in this research uses crystals in a cylinder like structure approximately 1/10,000 of a human hair in diameter to concentrate light. Not only can this be used in the development of new high efficiency solar cells but this technology is also expected to be applied in electronics and for the development of quantum computers.
The principles behind the use of nanowire crystals is that the diameter of the wire is smaller than the wavelength of sun light which causes it to bounce and resonate in and around the crystals thus concentrating the amount of light that is impacted on the areas of silicon that convert this into energy. This can achieve a concentration of sun light up to 15 times higher than what was previously thought possible through the “Shockley-Queisser Limit”, also referred to as detailed balance limit, which is defined by physics as a theoretical maximum limit for solar efficiency.
The Shockley-Queisser Limit was devised to measure the efficiency of single p-n junction solar cells with a specific band gap defining an efficiency of about 33.7% although most consumer solar cells use mono-crystalline cells which are only 22% efficient due to sunlight being reflected from the surface layer. The p-n junction model refers to a solar cell which uses p-type silicon on the anode connection and n-type silicon on the cathode connection for the crystal semiconductor.
Although the actual percentage of concentration may seem relatively small, it is important to understand that the previously described maximum solar efficiency limit by William Shockley and Hans Queisser in 1961 has been perhaps one of the single most fundamental developments in solar technology. The discovery of nanowire crystal technology has broken the barriers of what physicists previously perceived as a landmark in solar cell technology by increasing the once thought theoretical limit of solar efficiency. The leading researcher for this technology comes from Peter Krogstrup who has recently received his PhD from the Niels Bohr Institute, University of Copenhagen who believes despite the excitement caused by this research the actual implementation of this discovery for international solar power production will still take several years of research and development.