I can't find it now, but I seem to remember reading about a company that was adding solar cells to the wings of their self-launching electric sustainer glider.

I can't find it now, but I seem to remember reading about a company that was adding solar cells to the wings of their self-launching electric sustainer glider. The solar panels didn't generate anywhere near enough power to sustain cruising power, but the idea was that they could replenish the energy consumed by self-launching in the duration of a typical flight.