Sanyo Electric’s proprietary solar cell, the ‘heterojunction’ with intrinsic thin layer (HIT), has achieved a cell conversion efficiency of 22.3 per cent.

The latest conversion efficiency is an official record that was measured by Japan’s National Institute of Advanced Industrial Science and Technology (AIST). The cell measures 100.5cm2. It has a short-circuit current of 3.909A, an open-circuit voltage of 0.725V and a fill factor of 79.1 per cent. The maximum power per cell is 2.242W.

According to Sanyo, two key points improved the performance of the latest cell. In a HIT solar cell composed of a crystalline silicon layer sandwiched by amorphous silicon layers, the company improved the technology to wash the surface of the crystalline silicon layer prior to the formation of the amorphous silicon layers. The company also optimised the size and the shape of irreguarlities on the cell surface, which are provided to prevent reflection.

The company aims to enhance the cell conversion efficiency to 23 per cent at the research level, and to 22 per cent or higher at the mass production level by fiscal 2010.