**8.3 Deployable wings**

178 Solar Cells – Thin-Film Technologies

The solar arrays mounted on a satellite can have very different shapes, accommodations and dimensions. The configuration of a solar panel is the result of several design iterations made at satellite level, considering the mission requirements, the needed power, the dimensions, mass, and the spacecraft attitude to be kept during the whole lifetime and in all the possible satellite working modes. However three or four main configurations of the solar array can

The first configuration is the one characterising a spinning satellite. The satellite usually has cylindrical shape with the symmetry axis as the rotation one. This configuration was the first one to be adopted; the available power is not elevated with respect to the panel surface, indeed the equivalent active area results from the division of the actual area of panel by π. The satellite Meteosat is a good example; this configuration is nowadays rarely used, but in

Fig. 17. Solar Array for spinning Satellite, Meteosat Second Generation (Credits: ESA - MSG

The second configuration foresees the panels body mounted to the spacecraft walls. The panels are rigidly fixed to the structure and their orientation towards to the sun is never

This solution has been recently adopted for earth observation and scientific satellites with a reduced power need, no more than 1 kW. In case of earth observation satellites the nadir-

Fig. 18. Body mounted solar array, GOCE (Credits: ESA - AOES Medialab)

some cases is still interesting for scientific satellites like those of the Cluster mission.

**8. Solar array configurations** 

be identified.

Team)

optimal.

**8.2 Body mounted panels** 

**8.1 Spinning satellite** 

The third one is the classical double deployable wing. This solution is classical for telecommunication geostationary satellites. Each wing is moved by a Solar Array Driving Mechanism having the rotation axis perpendicular to the orbital plane. The illumination is optimized by the automatic orientation of the panels. This kind of configuration is the best solution when several kilowatts are needed, as in the case of recent telecom satellites. Each wing is then composed of several panels kept folded at launch, and then progressively deployed by suitable mechanisms at early phase of the mission. The satellite Hylas-1 gives a good example for such solution.

Fig. 19. Deployable Solar panels, Hylas-1 (Credits: ESA - J. Huart.)
