An alternative and simpler configuration of Airborne Solar Wind Energy Systems (ASWES) would be using mainly high altitude wind energy as any static (or crosswind) AWES operating in yo-yo mode, with solar energy used only to heat the air in a suitable kite so that the kite can remain in the air most of the time, even without wind, including night. So there would be no need for a challenging electric tether, expensive photovoltaic film, or absolute constraint on altitude.
A sketch below about two sorts of solar kites:
