A double envelope like this
allows to keep better the heat, in such a way that from 0.9 N per cubed meter, the aerostatic lift becomes about 1.3 N per cubed meter.
Assuming the double envelope balloon is a cylindrical Magnus rotor, the electrical motors used to rotate the balloon provide also some heat which is also better kept within the internal black envelope, and which adds some lift (a Peter Sharp’s good idea). If the volume is large enough, even a low aerostatic lift (due to the lack of direct radiation from the sun for a long time but thanks to both diffuse radiation and high volume of the double envelope) may be sufficient to keep the balloon in flight, even by very light winds.
So such a solar-heated by electrical motors-Magnus effect balloon could be a permanent lifting kite-aerostat for some AWES.