The advance of solar concentrators

Solar modules which trap light are an upcoming alternative to conventional photovoltaic technology. By means of this system, the American firm Semprius has been able to convert one third of their sunlight into electricity for the first time. For solar mechanical engineers, this promising technology of the future could potentially be a new pillar in the industry.

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Concentrating photovoltaics, in short CPV, is one of the many promising new technologies which could help photovoltaic technology quickly become a highly competitive force in the industry. By using lenses to trap sunlight on a semi-conductor, considerably more electrons are set in motion for the production of electricity – and at the same time, cell efficiency increases. The American firm Semprius has recently set a new efficiency record of 34 % thanks to a CPV module.

What makes this innovation so special? In contrast to experimental CPV concepts to date, which can also generate efficiency levels of 40 %, the modules are ready for commercial production. "Our module is the first to convert one third of sunlight into electricity outside of laboratories," says Joe Carr, the CEO of Semprius. The technology has also been a hit with the electronics company Siemens, based in Munich. Already last year, Siemens acquired a 16 % share of Semprius. With help from Siemens, this coming July, series production is set to begin in the company's own factory located in Henderson, in the US federal state of North Carolina.

The cells, manufactured by Semprius, consist of tiny gallium arsenide discs, upon which lenses are positioned. These discs trap light in such a way that sunlight hits the absorber with 1100 times more intensity. The advantage of this setup is that even cells with a diameter as small as a few millimetres can generate enough electricity – an important requirement for space-saving modules and cost savings.

Gallium arsenide captures the light much better than silicon, commonly used to date. Therefore, Semprius modules reach more than double the efficiency levels reached by conventional modules. Since the lenses only work in direct sunlight, they are mounted on so-called "trackers" which track the exact position of the sun.