MS XIV is designed to accommodate 4 occupants and consequently will require 4 seats. Seat construction typically involves several components including a structural frame, padding, and additional upholstery. The seats for MS XIV are intended to be rigidly fixed to the vehicle chassis for the sake of simplicity and safety.
The range of occupant sizes and seating positions was previously determined in past terms. The aggressive seating angle (very low and laid back angle) and limited occupant size for rear occupants was chosen in order to meet the aerodynamic form-factor of the vehicle. See Occupant Cell Sizing (Key Document)
Several key considerations that should be made are: designing for minimal seat weight, designing for maximum cooling/ventilation of occupants (since solar cars have no air-conditioning system), and designing around ballast storage compartment (to ensure fairness, all occupants are given a ballast of lead-shot to be placed near the hips to bring their weight to 80kg/176lbs).
(Above) Image of concept for seats