Toshinobu Matsutani

Non hot-spot PV module using solar cells with bypass diode function

The authors started to deliver terrestrial nonhot-spot photovoltaic modules using solar cells with the bypass diode function on the market. The bypass diode function is achieved by controlling cell reverse characteristics without increasing the cost. This function gives the bypass of current flow to the shaded cell when the module is shaded by unfavorable shields such as fallen leaves. Thus the advanced modules are able to show the more power output and the lower temperature increase than the conventional modules when a part of them is shaded.

Radiation Test of Silicon Solar Cells for Space Application

The degradation of electrical performance due to electron, high energy proton, and low energy proton irradiations was investigated for various space qualified modern solar cells. Electrical performance data taken under AMO/28°C conditions on the irradiated and annealed cells showed that conventional (Conv.) and BSR cells are the least sensitive to damage under high energy particle (electron and proton) irradiations. Black cells were more tolerant to the high energy particle irradiations than BSF cells, and showed the most excellent electrical performance among all types of solar cells after heavy irradiations. Covered cells (Black and BSFR cells) were irradiated with low energy protons. The Voc and Isc degradations of the cells could hardly be found, while the Pmax degradations were about 5%.

Development of high efficiency thin silicon space solar cells

The improvement of the efficiencies of thin silicon solar cells for space use was studied. The representative 3 types of nonreflective surface structures were evaluated and their characteristics were clarified. Solar cells with these structures showed excellent electrical performance and the best result of 18.0% efficiency for 100 /spl mu/m thick cells was attained. Cells made from 2 /spl Omega/ cm substrates showed higher electrical performance and radiation hardness than those from 10 /spl Omega/ cm substrates. The electron irradiation tests showed that the current degradation of the cells with lower resistivity substrates were reduced and the improved solar cells can be used for future satellites.<<ETX>>

Electrical properties of thin silicon space solar cells

Abstract Thin silicon solar cells with a Non-Reflective front Surface (NRS), a passivated rear surface and locally diffused BSF structure have been considered to be hopeful candidates as space solar cells of the next generation. In this paper, the electrical properties of textured surface cells and flat (non-textured) surface cells are compared and the surface recombination velocity S e of these cells are discussed. Then, the electrical properties of 10 Ω cm substrate cells and 2 Ω cm substrate cells are compared and the carrier recombination at the rear Si/SiO 2 interface is discussed using energy band diagrams.

Development of high efficiency silicon space solar cells

The cell design and manufacturing process for the high efficiency thin silicon space solar cells (call NRS/LBSF cell) were finalized and their characteristics were qualified. The 100 /spl mu/n NRS/LBSF cells showed efficiencies of maximum 18.5% and average 18.0%. After electron irradiation of 1E+15e/cm/sup 2/, the NRS/LBSF cell showed about 1.2 times higher output power than the conventional 200 /spl mu/m BSR cell.

New silicon space solar cells with IBF (integrated bypass function)

New silicon space solar cells with IBF (integrated bypass function) which enable prevention of a failure caused by a reverse biasing are proposed. To investigate the feasibility of these cells, some preliminary experiments were performed. From the results of these experiments, it is confirmed that these cells have no problems intrinsically as space solar cells and contribute to obtaining higher reliability of a solar array.

Ultrathin Silicon Solar Cell for Space Application

Ultrathin silicon (Si) solar cells for space application were fabricated on an experimental basis and the electrical characteristics were investigated for three kinds of cells (Black, BSFR and Conventional cells). Under 135.3 mW/cm2 (AMO) illumination, ultrathin Black cells showed 67.7 mW output, which is equal to 89% output of 280 µm Black cells. The power to mass ratio of bare ultrathin Black cells was 3.6 times high compared with 280 jum thick Black cells. 1 MeV electron irradiation test was carried out to evaluate the radiation resistance. Ultrathin cells showed superior radiation resistance compared with that of 280 µm thick cells, and it was comparable to that of a GaAs solar cell which had been recognized as a radiation resistive cell. Our experiments suggest that the ultrathin solar cells have high potential to be used for space application.