Development boosts photovoltaic efficiency

29 September 2009

A groundbreaking development for photovoltaic systems has emerged from Korea, boosting the efficiency of the solar cell and “condensing” the harvested sunlight. Maxon motor has supplied drives for a system that allows the panels to track the movement of the sun.

The power dense system is designed to most advantageously harvest energy from a so far still sparsely used natural resource.

Standard photovoltaic modules are usually limited to the photoelectric conversion of sunlight into electrical energy. Korean scientists say they have found a way to not only considerably improve the solar cells’ efficiency, but also to focus the incident sunlight and significantly boost overall efficiency.

Three novel elements contribute to the remarkable improvement in performance: The high-resolution, real-time tracking towards the sun, highly efficient focusing of the solar radiation prior to its conversion into electrical energy, and high-concentrated, extremely efficient solar cells.

Solar tracking of the panels is accomplished with two axis real-time control powered by maxon drives (brushless EC-max 30 mm motors with planetary gearhead GP 42 C) with a resolution of 0.0025 mm. Only this highly accurate positioning system allows optimised optical focusing. For that purpose, every individual solar cell is equipped with photo-optic condenser based on a Fresnel lens of a size of approximately 250 x 250mm. It condenses the sunlight by a factor of 300 to 500. Eventually, below the condenser positioned high-concentration solar cells are capable to generate up to 37 watts of electric energy – this on a surface of just one square cm (±0.15 square inches) and an efficiency of approximately 37 up to 40 per cent.

When compared to regular cells, the improvement is claimed to correspond to an increase of about 300 per cent.

The consistent implementation of optimised utilisation of the incident solar radiation results in a system of highest power density. Thus permitting self-contained systems composed of 12 modules, which require floor space of less than 20m² and possessing the capacity to deliver 3.2 kW/h of electrical energy.

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