Engineers at Airbus' facilities in France carrying out Biomass' tricky solar array deployment test - tricky because this is done in the cleanroom where gravity prevails and so this means that the test needs a rather complicated setup; of course, when it happens for real after the satellite has been injected into orbit, it will be free of gravity.
The solar array is a single wing comprising four panels. The panels open from the side of the satellite via a yoke, and once fully deployed the four panels rotate to a fixed angle. Outstretched, the wing has an area of just over five square metres and generates the power that the satellite needs.