IBM is working on two methods for making solar power cheaper, with the eventual goal of making it more affordable than using fossil fuels. A report from Ars Technica where they visited BM’s Watson research centre has revealed some more information on how IBM is trying to accomplish this and neither of the methods use silicon, the main material used in solar panels.
IBM’s alternatives to silicon are called thin films and concentrating photovoltaics. Thin films are less efficient than traditional silicon-based solutions but they have the potential to be significantly cheaper to make. Thin films differ from silicon products in that they are created from polycrystalline forms of the materials that they are based on rather than from a single crystal in the case of silicon.
One of the more common thin films is called CIGS, which stands for cadmium-indium-gallium-selenium, but gallium and indium are still to expensive to make thin films a viable alternative for solar panels. IBM, working with others, is developing a thin film called CZTS which would replace the expensive elements with zinc and tin. Thins films are markedly less efficient than their silicon counterparts however, with CIGS sitting at around 20% of light striking the panel being converted to electricity in lab conditions. CZTS was even lower at around 8% but the team hopes to reach a commercially viable 15% soon (CIGS thin film options on the market manage about 13% efficiency) after upping that limit to around 11%.
The other silicon-free solar option that IBM is working on is concentrating photovoltaics, which uses photovoltaic chips that are potentially more efficient that silicon. They are, however, also more expensive to use. A way around this is to use lenses to increase the amount of light that these chips can receive to make them more cost-effective but this introduces a heating problem. IBM had developed a liquid gallium-indium alloy that could be used as a thermal couple to help cool photovoltaic chips which was used as the basis for a first generation device. This has since been replaced with an unspecified technology co-developed with Saudi Arabia’s King Abdulaziz City for Science and Technology (KACST) that concentrates sunlight onto photovoltaic chips while simultaneously cooling the rectangular unit it is housed in.
Concentrating photovoltaics is nearing the magic $2 per Watt number but IBM isn’t just spreading its eggs over more than one basket. The two technologies have different implementations and the photovoltaics solution is particular relies on large amounts of direct sunlight to function, hence the involvement of KACST. Thin films may find a use in areas that are not constantly sunny, perhaps making solar power far more viable all over the world.
Source: Ars Technica