Photovoltaic concentrator using a holographic optical element

A photovoltaic concentrator is proposed that uses equatorial tracking (the rotation axis of a concentrator points to the North Star), so that the change of the sun's altitude angle is minimized. The solar concentrator consists of a Fresnel lens (objective), a holographic optical element made on photoresist with 90% diffraction efficiency, and a field lens (making the sunlight come from different fields of view uniformly falling on the solar cell). The accuracy of the original 2-D tracking is reduced several orders over previous methods; however, it may be that only 1-D tracking is needed. A theoretical analysis and a study model have been made, and a reasonable concentration ratio has been obtained. Therefore, it can be expected that the cost will be much lower than an accurate 2-D tracking system.