A genuine circular contact grid pattern for solar cells

A model was developed for a genuine circular contact grid, based on the same principles that led to previously reported models for other contact grid types. The circular grid differs from the regular (radial) grid often applied to round solar cells, in that it has considerably less radial lines and many more concentric rings, to the effect that the rings now take on the role of fingers, while the lines serve as busbars. For a 16 mm² n‐on‐p GaAs cell and irradiances ranging from 1 to 1000 suns, optimised grids of this new circular design were compared to equivalent radial, square and inverted square grids. Furthermore, in order to allow for a fair comparison of the different grid types, the previously reported radial grid model was modified to obtain additional freedom in design that is comparable to that of the other grid configurations. The circular grid turned out to suffer less power loss than a comparable radial grid up to a concentration ratio of 30. At higher concentration ratios, cells with a radial grid performed better, while comparable square and inverted square grids perform better over the entire range of concentration ratios. For GaAs cells serving as the bottom cell in a mechanical tandem, the effects of secondary shadowing were calculated for a range of translational and rotational misalignments, for the four patterns optimised for the case where the GaAs cell is effectively subjected to a concentration ratio of 500. The effects of translational misalignment varied little between the grids, but the rotational misalignment effects demonstrated the strength of the circular grid, since its shadowing loss hardly increases with increasing rotational misalignment angle, while those of the other three grid types quickly approach a doubling. When these secondary shadowing effects are taken into account, the circular grid can be the preferred pattern for the constituent cells of a mechanical stack, depending on the accuracy with which those cells can be rotationally aligned. Copyright © 2011 John Wiley & Sons, Ltd.     

Erratum: Correction to November 2011 ‘Worldly Perspectives’ authors

The bylines and the credits for the November Alternatives “Worldly Perspectives” column were incorrectly assigned. In “France Attempts To Boost Mediation Through Court Experimentation,” 29 Alternatives 179 (November 2011), the authors' byline should have been Jean‐Georges Betto and Adrien Canivet. Worldly Perspectives columnists Giuseppe De Palo and Mary B. Trevor should have been credited with collaborating and editing. Alternatives apologizes to Betto and Canivet and readers for the error. Archival database editions will reflect the correction.     

Corrigendum to ‘Solar cell efficiency tables (version 49)’[Prog. Photovolt: Res. Appl. 2017; 25:3–13]

Version 49 of these efficiency tables reported confirmed new solar cell results from July – December 2016. Three errors are corrected and three new results received after the publication cut‐off date are briefly reviewed. Copyright © 2017 John Wiley & Sons, Ltd.     

Response to “Comment on ‘Negative Schottky barrier between titanium and n-type Si(0 0 1) for low-resistance ohmic contacts”’ [Solid State Electron. 2004;48:335–8]

The measurement of a negative or low Schottky barrier is complicated by several factors, including series resistance. With these factors in mind and additional experimental results, we reaffirm that the barrier height between Ti and Se-passivated n-type Si(0 0 1) is negative or nearly negative.