Nanotechnlogies at the service of photovoltaic

Norwegian researchers have found the system to produce thinner solar cells than the current ones and, keeping performances unchanged, they will allow decreasing the silicon consumption by 95%

When a technology becomes consolidated with large-scale productions, this is generally the optimization time, with researches aimed at both obtaining better efficiency and at granting the same results with the use of fewer materials, pursuing a goal of maximum miniaturization. It is the case of solar cells, basis of photovoltaic panels. At present about 90% of the electricity generated by photovoltaic panels is obtained with silicon modules whose thickness is around 200 micrometres, and considering that every year several billions are produced, the enormous silicon consumption is becoming evident: almost 5 grams per watt produced. Even if silicon is one of the most common elements on our planet, pure silicon does not exist in nature, and a solar module can operate if it is constituted by silicon only at least by 99.9999%: in other words, if more than one millionth of another material is present, it does not function. Pure silicon can be obtained with processes at 2000°C, with great quantities of energy and also, due to the process, waste of material, considering that only 50% of the silicon is then really transformed into solar cells, and the remaining part becomes sand again. It is worth adding that the price of photovoltaic panels is decreasing, by about half Euro per watt, while just four years ago it was two Euros per watt, and the margin reduction induces producers to look for cheaper production processes. A solution has been probably found in Norway, result of a joint research of the Research Centre for Solar Cell Technologies and the Physics Department of Oslo University, with the development of thinner solar cells, just 20 micrometres, determining a potential silicon saving by 95%. But with such subtle solar cells most of the incident light passes through, with drastic decrease of the one usable for the electricity generation. The solution found by Norwegian researchers is based on the “light harvesting” principle, that’s to say imposing a longer permanence time in the solar cell to the light, and this by placing on the cells a layer of microscopic plastic balls, all having exactly the same size, the Uglestad microbeads, from the name of their inventor in 1976. In this way an apparent 25-time bigger thickness has been achieved, even with a real thickness that is still 20 micrometres. We foresee that the new ultra-subtle solar cells will be available on the market within 5-7 years at the latest.


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