**8.2 Body mounted panels**

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 optimal.

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

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 nadirpointing attitude of the instruments results in highly variable illumination of the panel, therefore the computation energy budget can be quite challenging because the power subsystem may have power coming from both solar array and battery pack at the same time along the orbit. This behaviour may significantly reduce the useful time for the recharge of the battery in sunlight, and an oversized solar panel may be needed. The ESA spacecraft GOCE is a good example of such body mounted panels; two of them are installed on the fixed "wings" of the satellite, the other two are on the "fuselage". It is worth to note that the temperatures on the solar panels are very different between one another, this because of the different illumination levels and different thermal exchange of the wings (remaining colder) with respect to the fuselage (hotter panels). Such configuration, dictated by many other requirements at satellite level, can have a huge impact in the complexity of the power conditioning concept to be adopted.
