The field in the i-layer of an amorphous-silicon solar cell may be assumed as uniform. We formulate the respective cell model without further approximations in terms of a "regional method". The i-layer is subdivided for that purpose in many regions, and the regional solutions an chained together. Some exemplary simulations are presented. The model is in particular suited to demonstrate snake-like low-forward-voltage photocharacteristics, to be induced by near-surface excess carrier generation, as with blue illumination. Observed and simulated "blue-snake" characteristics are compared with each other. A snake indicates the transition from a bulk-recombination to a surface-recombination limited current regime.