Mumbai University > Satellite Communication and Networks

Marks: 4M

On spin-stabilized satellites, the solar panels form the exterior envelope of the body of the satellite.The number of cells required is large since they are not all illuminated by the sun at the same time.

By considering a cylinder with its axis normal to the direction of radiation, the variation of incidence between cells located on the illuminated side leads to a surface area which must be π/2 times greater than that of a plane perpendicular surface for the same power. Including the surface in shadow, the number of cells to be installed is thus π times greater than if the panels were flat.

In three axis stabilized satellite once deployed, the solar generator wings are rotated in order to follow the apparent movement of the sun about the satellite. For a geostationary satellite, the generator wings are aligned with the pitch axis and rotation is daily.

A cylindrical spin-stabilized satellite must carry a larger number of solar cells than an equivalent three-axis stabilized satellite, because only about one-third of the cells are exposed to the sun at any one time.The three-axis stabilized satellite configuration allows for better utilization of solar cell area, because the cells can be arranged in flat panels, or sails, which can be rotated to maintain normal exposure to the sun – levels up to 10kW are attainable with rotating panels.